Open Access. Powered by Scholars. Published by Universities.®

Medicine and Health Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

1997

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 1 - 30 of 929

Full-Text Articles in Medicine and Health Sciences

Prevention Of Retained Placenta By Injection Of Collagenase Into Umbilical Arteries Of Calves Delivered By Cesarean Section: A Tolerance Study, Hugo Eiler, P Wan, N Valk, Kellie Fecteau Jun 2014

Prevention Of Retained Placenta By Injection Of Collagenase Into Umbilical Arteries Of Calves Delivered By Cesarean Section: A Tolerance Study, Hugo Eiler, P Wan, N Valk, Kellie Fecteau

Kellie Fecteau

In the cow, cesarean section delivery is often followed by retention of fetal membranes. Hypothetically, the retention of fetal membranes could be prevented by intraplacental injections of the enzyme collagenase. However, the infusion of this potent proteolytic enzyme into a uterus traumatized by surgery can lead to uterine damage, including perforation. Thus, the objective of this research was to evaluate tolerance of intraplacental treatment of bacterial collagenase. A cesarean section was performed on 10 experimental cows undergoing induced delivery or diagnosed with dystocia. During the surgical procedure, 200,000 units of bacterial collagenase in 1 L of saline were infused ...


Investigation Of The Effects Of Hyperthyroidism On Renal Function In The Cat, William Adams, G Daniel, Alfred Legendre May 2013

Investigation Of The Effects Of Hyperthyroidism On Renal Function In The Cat, William Adams, G Daniel, Alfred Legendre

Alfred M Legendre DVM, MS, DACVIM

This study evaluated the effects of thyroxine on renal function in the cat. Baseline serum thyroxine (T4) concentrations, clinicopathologic data (complete blood count [CBC], serum chemistry panel, urinalysis), and nuclear medicine determinations of glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and effective renal blood flow (ERBF) were measured in 10 normal adult cats. Cats were then injected with thyroxine (T4) (50 micrograms/kg SQ) daily for 30 d to induce hyperthyroidism. Clinicopathologic and nuclear medicine studies were repeated at 30 d. Cats injected with thyroxine had significant increases in T4, GFR, and ERBF and significant declines in serum ...


Magnetic Resonance Imaging Appearance Of Intracranial Hemorrhage Secondary To Cerebral Vascular Malformation In A Dog, William Thomas, William Adams, M Mcgavin, Rebecca Gompf May 2013

Magnetic Resonance Imaging Appearance Of Intracranial Hemorrhage Secondary To Cerebral Vascular Malformation In A Dog, William Thomas, William Adams, M Mcgavin, Rebecca Gompf

William B. Thomas, MS, DACVIM (Neurology)

A 14-year-old dog developed an acute onset of depression, disorientation, left hemiparesis,left hemianopia, left facial hypoesthesia, and a tendency to turn to the right. Based on these findings, a lesion affecting the right forebrain was suspected. Magnetic resonance imaging showed a mass within the right cerebral hemisphere resulting in compression of the right lateral ventricle and shifting the longitudinal fissure to the left. The lesion was hyperintense on T1-weighted images and hyperintense with focal regions of hypointensity on proton density-, and T2-weighted images, consistent with a subacute hemorrhage. At necropsy, there was a hematoma in the parietal portion of ...


Changes In Renal Function In Cats Following Treatment Of Hyperthyrodism Using I131, William Adams, Gregory Daniel, Alfred Legendre, Rebecca Gompf, Cynthia Gove Feb 2013

Changes In Renal Function In Cats Following Treatment Of Hyperthyrodism Using I131, William Adams, Gregory Daniel, Alfred Legendre, Rebecca Gompf, Cynthia Gove

William H Adams, DVM, DACVR

Changes in renal fnction of twenty-two cats treated for hyperthyrodism using radioiodine were evaluated. Serum thyroxine (T4), serum creatinine, blood urea nitrogen (BUN) and urine specificgravity were measured before treatment and 6 and 30 days after treatment. Twenty-two cats had pretreatment and 21 cats had 6 day posttreatment measurement of glomercular filtration rate (GFR) using nuclear medicine imaging techniques. there were significant declines in serum T4 at 6 days following treatment, but the changes in GFR, serum creatinine and BUN were not significant. At 30 days following treatment, there were significant increases in BUN and serum creatinine and further significant ...


Mental Health Parity: National And State Perspectives: A Report, Bruce Levin, Ardis Hanson, Richard Coe, Ann Taylor Oct 2011

Mental Health Parity: National And State Perspectives: A Report, Bruce Levin, Ardis Hanson, Richard Coe, Ann Taylor

Bruce Lubostsky Levin, DrPH, MPH

This report contains a summary of the available information on the key issues involved in parity initiatives: the experiences at the national level (see “National Parity Initiatives”) as well as the experiences of other states that have developed and/or implemented parity legislation (see “State Parity Initiatives”); the cost experiences resulting in implementing parity for mental disorders (see Costs”); and implications and suggestions for proceeding with the development of mental health parity in Florida (see "Evaluating Benefits from Mental Health Parity” and “Conclusions”).


Changes In Renal Function In Cats Following Treatment Of Hyperthyrodism Using I131, William Adams, Gregory Daniel, Alfred Legendre, Rebecca Gompf, Cynthia Gove Aug 2011

Changes In Renal Function In Cats Following Treatment Of Hyperthyrodism Using I131, William Adams, Gregory Daniel, Alfred Legendre, Rebecca Gompf, Cynthia Gove

Alfred M Legendre DVM, MS, DACVIM

Changes in renal fnction of twenty-two cats treated for hyperthyrodism using radioiodine were evaluated. Serum thyroxine (T4), serum creatinine, blood urea nitrogen (BUN) and urine specificgravity were measured before treatment and 6 and 30 days after treatment. Twenty-two cats had pretreatment and 21 cats had 6 day posttreatment measurement of glomercular filtration rate (GFR) using nuclear medicine imaging techniques. there were significant declines in serum T4 at 6 days following treatment, but the changes in GFR, serum creatinine and BUN were not significant. At 30 days following treatment, there were significant increases in BUN and serum creatinine and further significant ...


Effect Of Acepromazine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach Aug 2011

Effect Of Acepromazine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach

Thomas J Doherty

The effect of i.v. acepromazine (0.05 mg/kg bwt), butorphanol (0.05 mg/kg bwt) and a combination of acepromazine and butorphanol on halothane minimum alveolar concentration (MAC) was determined in 7 mixed-breed ponies. Ventilation was controlled, and blood pressure and temperature were maintained within normal limits. Following the determination of baseline MAC, treatments were administered to each pony in a random manner. The control treatment was normal saline. The baseline halothane MAC for the control group was 0.910.04%, and no significant change occurred after saline administration. Acepromazine decreased the halothane MAC from 0.920.02 ...


Effect Of High Volume Epidural Morphine, Ketamine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach Aug 2011

Effect Of High Volume Epidural Morphine, Ketamine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach

Thomas J Doherty

The effects of epidurally administered morphine, ketamine and butorphanol on halothane minimum alveolar concentration (MAC) was studied. 7 ponies were anaesthetised with thiopentone and succinylcholine, intubated and had anaesthesia maintained with halothane. Ventilation was controlled and blood pressure was maintained within normal limits. Following the determination of baseline halothane MAC for the pelvic and thoracic limbs, the ponies were given morphine (0.1 mg/kg bwt), ketamine (0.8 or 1.2 mg/kg bwt), butorphanol (0.05 mg/kg bwt) or saline, epidurally, to a final volume of 0.15 ml/kg bwt. The halothane MAC for the pelvic ...


Effect Of Acepromazine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach Oct 2010

Effect Of Acepromazine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach

Dennis R. Geiser DVM, DAVBP

The effect of i.v. acepromazine (0.05 mg/kg bwt), butorphanol (0.05 mg/kg bwt) and a combination of acepromazine and butorphanol on halothane minimum alveolar concentration (MAC) was determined in 7 mixed-breed ponies. Ventilation was controlled, and blood pressure and temperature were maintained within normal limits. Following the determination of baseline MAC, treatments were administered to each pony in a random manner. The control treatment was normal saline. The baseline halothane MAC for the control group was 0.910.04%, and no significant change occurred after saline administration. Acepromazine decreased the halothane MAC from 0.920.02 ...


The Effect Of Epidural Xylazine On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach Oct 2010

The Effect Of Epidural Xylazine On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach

Dennis R. Geiser DVM, DAVBP

The effects of epidurally administered xylazine on halothane minimum alveolar concentration (MAC) were examined in 6 healthy pony geldings. Anaesthesia was induced with i.v. administration of thiopentone (4 mg/kg) and succinylcholine (0.15 mg/kg) and maintained with halothane in oxygen. Following baseline halothane MAC determination, each pony was given 0.15 mg/kg xylazine hydrochloride or saline epidurally. No change in halothane MAC was observed following saline administration. Xylazine administration, however, significantly decreased halothane MAC from 0.93 to 0.61% in the thoracic limb and from 0.93 to 0.53% in the pelvic limb. Recovery ...


Effect Of High Volume Epidural Morphine, Ketamine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach Oct 2010

Effect Of High Volume Epidural Morphine, Ketamine And Butorphanol On Halothane Minimum Alveolar Concentration In Ponies, Thomas Doherty, Dennis Geiser, Barton Rohrbach

Dennis R. Geiser DVM, DAVBP

The effects of epidurally administered morphine, ketamine and butorphanol on halothane minimum alveolar concentration (MAC) was studied. 7 ponies were anaesthetised with thiopentone and succinylcholine, intubated and had anaesthesia maintained with halothane. Ventilation was controlled and blood pressure was maintained within normal limits. Following the determination of baseline halothane MAC for the pelvic and thoracic limbs, the ponies were given morphine (0.1 mg/kg bwt), ketamine (0.8 or 1.2 mg/kg bwt), butorphanol (0.05 mg/kg bwt) or saline, epidurally, to a final volume of 0.15 ml/kg bwt. The halothane MAC for the pelvic ...


Proactive Technique For Workplace Chemical Exposure, James A. Duru Dec 1997

Proactive Technique For Workplace Chemical Exposure, James A. Duru

Theses

The rapid increase in the number and quantities of chemicals released into the environment has been accompanied by a lack of adequate pre-released testing for advance health outcomes. Chemicals which serve as feed stock to millions of industries all around the world to produce and process food, cosmetics, equipment, and energy to propel industries, automobiles, home heating and electricity have serious adverse health consequences. They are hazardous. These substances can explode, ignite, react and corrode. Adapting the definition of the international program on chemical safety, a "hazard" is a source of danger. This thesis proposes some proactive prevention techniques useful ...


Interview With Richard T. Jones, Richard T. Jones (Interviewee), Joan Ash (Interviewer), Linda A. Weimer (Interviewer) Dec 1997

Interview With Richard T. Jones, Richard T. Jones (Interviewee), Joan Ash (Interviewer), Linda A. Weimer (Interviewer)

Oral History Collection

In this four-part interview, Dr. Jones talks about the medical men in his family, including his father, Dr. Lester T. Jones, his medical and further doctoral education in chemistry, his research on hemoglobins, and his career as professor, Chair of the Department of Biochemistry, Acting President of University of Oregon Health Sciences Center, and his other positions. Among the many people he reminisces about are Dean David Baird, John Benson, Paul Blachly, Joseph Bloom, President Lewis Bluemle, David Bristow, Gary Chiodo, Neil Goldschmidt, Dean Charles Holman, Donald Kassebaum, Robert Koler, Marion and Bill Krippaehne, Olof Larsell, President Leonard Laster, Chancellor ...


Interview With Marion Krippaehne, Marion Krippaehne (Interviewee), Linda A. Weimer (Interviewer) Dec 1997

Interview With Marion Krippaehne, Marion Krippaehne (Interviewee), Linda A. Weimer (Interviewer)

Oral History Collection

Dr. Krippaehne talks about her early life, her student days at University of Oregon Medical School in the 1940s, her husband William Krippaehne, who was chair of the Department of Surgery, her interest in mentoring female medical students, and the years of university expansion and its effects on the neighborhood.


A Linkage Map Of The Canine Genome, Cathryn Mellersh, Amelia Langston, Gregory Acland, Melissa Fleming, Kunal Ray, Neil Weigand, Leigh Francisco, Mark Gibbs, Gustavo Aguirre, Elaine Ostrander Dec 1997

A Linkage Map Of The Canine Genome, Cathryn Mellersh, Amelia Langston, Gregory Acland, Melissa Fleming, Kunal Ray, Neil Weigand, Leigh Francisco, Mark Gibbs, Gustavo Aguirre, Elaine Ostrander

Gustavo D. Aguirre, VMD, PhD

A genetic linkage map of the canine genome has been developed by typing 150 microsatellite markers using 17 three-generation pedigrees, composed of 163 F2individuals. One hundred and thirty-nine markers were linked to at least one other marker with a lod score ≥ 3.0, identifying 30 linkage groups. The largest chromosome had 9 markers spanning 106.1 cM. The average distance between markers was 14.03 cM, and the map covers an estimated 2073 cM. Eleven markers were informative on the mapping panel, but were unlinked to any other marker. These likely represent single markers located on small, distinct canine chromosomes ...


Construction Of A Panel Of Canine–Rodent Hybrid Cell Lines For Use In Partitioning Of The Canine Genome, Amelia A. Langston, Cathryn S. Mellersh, Cassandra L. Neal, Kunal Ray, Gregory M. Acland, Mark Gibbs, Gustavo D. Aguirre, R.E. K. Fournier, Elaine A. Ostrander Dec 1997

Construction Of A Panel Of Canine–Rodent Hybrid Cell Lines For Use In Partitioning Of The Canine Genome, Amelia A. Langston, Cathryn S. Mellersh, Cassandra L. Neal, Kunal Ray, Gregory M. Acland, Mark Gibbs, Gustavo D. Aguirre, R.E. K. Fournier, Elaine A. Ostrander

Gustavo D. Aguirre, VMD, PhD

We have constructed a collection of canine–rodent microcell hybrid cell lines by fusion of canine fibroblast microcell donors with immortalized rodent recipient cells. Characterization of the hybrid cell lines using a combination of fluorescencein situhybridization and PCR analysis of canine microsatellite repeat sequences allowed selection of a panel of hybrids in which most canine chromosomes are represented. Approximately 90% of genetic markers and genes that were tested could be assigned to 1 of 31 anonymous canine chromosome groups, based on common patterns of retention in the hybrid set. Many of these putative chromosome groups have now been ...


Interview With May E. Rawlinson, May E. Rawlinson (Interviewee), Joan Ash (Interviewer), Linda A. Weimer (Interviewer) Dec 1997

Interview With May E. Rawlinson, May E. Rawlinson (Interviewee), Joan Ash (Interviewer), Linda A. Weimer (Interviewer)

Oral History Collection

Dr. Rawlinson reminisces about her years as a student in the Department of Nursing Education at the University of Oregon Medical School during the 1940s. She describes Director Elnora Thomson. Then she recalls her experience in the U.S. Navy during World War II after graduation. She talks about her doctoral research. She discusses the development of the faculty and the nursing education programs in University of Oregon School of Nursing during the 1970s and the changes that occurred when the schools consolidated in the mid 1970s.


Comparison Of Beta-Adrenoceptor Coupled Camp Production In Cultured Human Mononuclear Leukocytes And Myometrial Cells, Yu-Li Liu Dec 1997

Comparison Of Beta-Adrenoceptor Coupled Camp Production In Cultured Human Mononuclear Leukocytes And Myometrial Cells, Yu-Li Liu

Electronic Theses and Dissertations

$\beta\sb2$-Adrenoceptor ($\beta\sb2$-AR) agonists, such as terbutaline, are used as tocolytic agents in the treatment of preterm labor. $\beta$-Adrenoceptor stimulation relaxes myometrium through specific receptors coupled through Gs to adenylyl cyclase (AC) that catalyzes the conversion of ATP to cAMP. The purpose of this study was to compare $\beta$-adrenoceptors and cAMP production in cultured human leukocytes and myometrial cells, and to determine the importance of $\beta$-adrenoceptors and cAMP production in isoproterenol-induced myometrial relaxation. $\sp{125}$I-iodopindolol was used to assess $\beta$-adrenoceptor affinity and number cAMP levels were analyzed before and after stimulation by ...


Cardiac Parasympathetic Dysfunction In Morphine Addiction, Leslie D. Napier B.S. Dec 1997

Cardiac Parasympathetic Dysfunction In Morphine Addiction, Leslie D. Napier B.S.

Theses and Dissertations

Napier, Leslie D., Cardiac Parasympathetic Dysfunction in Morphine Addiction. Doctor of Philosophy (Biomedical Sciences), December, 1997, 137 pp., 9 tables, 22 figures, references, 163 titles. The effects of chronic morphine treatment on parasympathetic control of the heart and associated cellular mechanisms were examined using a canine model. Vagal bradycardia was significantly blunted in dogs treated for one week with subcutaneous morphine pellets. In a separate group of dogs, heart rate and high frequency fluctuations in heart rate declined during the first three hours of subcutaneous morphine infusion consistent with the vagatonic action of acute morphine. Heart rate remained below baseline ...


Diabetes And Exercise: The Role Of The Athletic Trainer, Carolyn C. Jimenez Dec 1997

Diabetes And Exercise: The Role Of The Athletic Trainer, Carolyn C. Jimenez

Sports Medicine

No abstract provided.


Interview With Barbara Gaines, Barbara Gaines (Interviewee), Joan Ash (Interviewer), Linda A. Weimer (Interviewer) Dec 1997

Interview With Barbara Gaines, Barbara Gaines (Interviewee), Joan Ash (Interviewer), Linda A. Weimer (Interviewer)

Oral History Collection

Gaines talks about her experiences as a nursing instructor at University of Oregon School of Nursing under Dean Jean Boyle. She describes her transition to administrative responsibilities under Dean Carol Lindeman after 1976. She reviews changes in the School of Nursing from the 1960s onward and then talks about her interest in nursing history and her manuscript history of the School of Nursing.


Texas D.O. Volume 54, Number 11, Texas Osteopathic Medical Association Dec 1997

Texas D.O. Volume 54, Number 11, Texas Osteopathic Medical Association

Texas Osteopathic Physicians Journal

No abstract provided.


Update - December 1997, Loma Linda University Center For Christian Bioethics Dec 1997

Update - December 1997, Loma Linda University Center For Christian Bioethics

Update

In this issue:

-- "Spirituality and Ethics in Patient Care"
-- Mind Manipulation: A Christian Ethical Analysis
-- Hobergs, Silk Hose, and Hypnosis


The Morality Of Intimate Faculty-Student Relationships, Nicholas Dixon Dec 1997

The Morality Of Intimate Faculty-Student Relationships, Nicholas Dixon

Center for the Study of Ethics in Society Papers

Presented September 19, 1996 for the Center for the Study of Ethics in Society


The Biography Of A Scale: Contextual Factors That Influence The Measurement Of Family Functioning, Ludwig Geismar Dec 1997

The Biography Of A Scale: Contextual Factors That Influence The Measurement Of Family Functioning, Ludwig Geismar

The Journal of Sociology & Social Welfare

The subject of instrument relevance is addressed by examining issues that have arisen in the use of a single scale over a forty year period. The issues revolve around the impact of varying social conditions, changing ethos, differential respondent receptiveness, and evolving research technology. Extended use of an instrument, it is argued, yields information that transcends the conventional techniques for testing instrument adequacy. The lack of opportunities in social work for accessing information on extended use of measurement tools is due, among other factors, to a preoccupation with working on subjects that are new and original and to a lack ...


Interaction Of Gaba And Excitatory Amino Acids In The Basolateral Amygdala: Role In Cardiovascular Regulation, Robert P. Soltis, Jennifer C. Cook, Adam E. Gregg, Brian J. Sanders Dec 1997

Interaction Of Gaba And Excitatory Amino Acids In The Basolateral Amygdala: Role In Cardiovascular Regulation, Robert P. Soltis, Jennifer C. Cook, Adam E. Gregg, Brian J. Sanders

Scholarship and Professional Work – COPHS

Activation of the amygdala in rats produces cardiovascular changes that include increases in heart rate and arterial pressure as well as behavioral changes characteristic of emotional arousal. The objective of the present study was to examine the interaction of GABA and excitatory amino acid (EAA) receptors in the basolateral amygdala (BLA) in regulating cardiovascular function. Microinjection of the GABAA receptor antagonist bicuculline methiodide (BMI) or the E A A receptor agonists NMDA or AMPA into the same region of the BLA of conscious rats produced dose-related increases in heart rate and arterial pressure. Injection of the nonselective EAA receptor ...


Anthroposophic Perspectives In Primary Care, Ira S. Cantor Md, Steven Rosenzweig Md Dec 1997

Anthroposophic Perspectives In Primary Care, Ira S. Cantor Md, Steven Rosenzweig Md

Department of Emergency Medicine Faculty Papers

A core challenge of contemporary medicine is to integrate the technological successes of biomedical science with a comprehensive under-standing of the physical, psychosocial, ecological, and spiritual dimensions of health and illness. Toward this end, bridges are being created between conventional medicine and alternative systems of healing which reflect a holistic model of the human being. Even when both conventional and complementary approaches are used side-by-side in the same patient, they remain separate in their basic assumptions and goals. Today's mechanistic disease model is cut off from such notions as life-energy, consciousness, and spirituality, so integral to many alternative paradigms ...


Jefferson Alumni Bulletin – Volume Xlvii, Number 1, December 1997 Dec 1997

Jefferson Alumni Bulletin – Volume Xlvii, Number 1, December 1997

Jefferson Medical College Alumni Bulletin

Jefferson Alumni Bulletin – Volume XLVII, Number 1, December 1997 Annual Giving Celebrates a Half-Century of Strengthening Jefferson, Page 4 Screening for Breast Cancer: A Continuing Dilemma, Page 8 The McClellan house: A Link to the University’s Past, Page 12 The Bulletin Reaches its 75th Year, Page 17 Landmark Breast Cancer Meeting at Jefferson, Page 21 University and SmithKline Beecham Link Clinical Research, Page 22 Missing Cancer-Suppressor Genes May Have Deadly Effects, Page 23 Goldstein is Vice President for Research at JDFI, Page 27 Brezinski Develops Noninvasive Method to Detect Early Signs of Cancer and Heart Attacks, Page 29


Narrative Development In Late Talkers: Early School Age, Rhea Paul, Rita Hernandez, Lisa Taylor, Karen Johnson Dec 1997

Narrative Development In Late Talkers: Early School Age, Rhea Paul, Rita Hernandez, Lisa Taylor, Karen Johnson

Speech-Language Pathology Faculty Publications

Children with slow expressive language development (SELD) as toddlers and a control group of children with normal language development (NL) were followed to early school age. Children with SELD were, at that point, subdivided into two groups: those who had moved within the normal range of expressive language (the History of Expressive Language Delay [HELD] subgroup); and those who continued to score below the normal range in expressive language at school age (the Expressive Language Delay [ELD] subgroup). During their kindergarten, first, and second grade years, they were administered a narrative generation task. Narratives were analyzed for MLU, lexical diversity ...


Direct Demonstration Of Retroviral Recombination In A Rhesus Monkey, Dawn P. Wooley, Randall A. Smith, Susan Czajak, Ronald C. Desrosiers Dec 1997

Direct Demonstration Of Retroviral Recombination In A Rhesus Monkey, Dawn P. Wooley, Randall A. Smith, Susan Czajak, Ronald C. Desrosiers

Neuroscience, Cell Biology & Physiology Faculty Publications

Recombination may be an important mechanism for increasing variation in retroviral populations. Retroviral recombination has been demonstrated in tissue culture systems by artificially creating doubly infected cells. Evidence for retroviral recombination in vivo is indirect and is based principally on the identification of apparently mosaic human immunodeficiency virus type 1 genomes from phylogenetic analyses of viral sequences. We infected a rhesus monkey with two different molecularly cloned strains of simian immunodeficiency virus. One strain of virus had a deletion in vpx and vpr, and the other strain had a deletion in nef. Each strain on its own induced low virus ...