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Biomedical subjects

C Roberts

Publications and source records attributed to C Roberts.

At least 307 records · Page 17Linked to original sources
PubMed1990

Mechanics of breathing during strenuous exercise in Thoroughbred horses.

The changes induced by exercise on the mechanics of breathing, as well as the simultaneous changes occurring in arterial blood gas tensions and in respiratory gas exchange were investigated in 6 healthy thoroughbred horses, performing a treadmill exercise of increasing intensity. Respiratory airflow and tidal volume (VT) were measured with ultrasonic flowmeters. Pleural pressure changes were measured by an oesophageal balloon catheter. Gas concentration of the expired air was analysed with a mass spectrometer; the oxygen consumption (VO2) and the carbon dioxide output (VCO2) were computed breath-by-breath. Arterial blood gas values were obtained by sampling from the carotid artery. Between rest and fast gallop VT, respiratory frequency, expired minute ventilation (VE), VO2, VCO2, total pulmonary resistance (RL), mechanical work of breathing (Wrm) and PaCO2 increased significantly while PaO2 decreased significantly. The Wrm.VO2(-1) ratio in galloping horses increased exponentially with VE. This, together with the relationship between the changes in PaO2 and in PaCO2 and the increase in the ventilatory mechanics parameters, suggests that the mechanics of breathing may be one of the factors constraining further increase in ventilation in exercising healthy horses.

Animals↗
PubMed1990

Cytogenetic analysis of biopsied preimplantation mouse embryos: implications for prenatal diagnosis.

Genetic diagnosis of enzyme deficiencies have been developed in mouse models using biopsied preimplantation embryos. A technique for preimplantation cytogenetic analysis was developed using embryos which were biopsied at the 4-cell, 8-cell and morula stage. Three culture methods were compared, using exposure directly to colchicine or preculture or overnight culture with subsequent exposure to colchicine. Some biopsies were lost through cell death (4.7-20.3%) and technical problems (11.1-27.8%), whilst others remained in interphase (13.0-46.5%). Air-dried preparations were successfully G-banded and karyotyped by modifying routine banding procedures. Biopsies placed directly into colchicine yielded the greatest mitotic index. However, chromosome morphology was unsuitable for G-banded analysis. After a short preculture, 71.4% of fixed 8-cell biopsies were karyotyped. The success of analysis of 8-cell biopsies is probably partly related to the higher mitotic index of intact embryos at this stage. Loss of chromosomes through scatter and chromosome overlapping limited analysis, particularly in biopsies with only one metaphase. The present success rate is not acceptable for the application of this technique to human prenatal diagnosis. However, it presents a useful tool for the study of chromosomal error at the research level.

Animals↗
PubMed1990

The role of mammography in detecting breast cancer in augmented breasts.

Recent reports suggest that mammographic findings may be compromised in patients who have undergone augmentation mammoplasty. Therefore, early detection of breast cancer by mammography may be obscured. We reviewed records for our patients with breast cancer after augmentation mammoplasty to define further the role and accuracy of mammography. Six patients aged 34 to 52 years (mean, 42 years) had a diagnosis of breast carcinoma 4 to 14 years (mean, 7.2 years) after augmentation mammoplasty. Five patients had preoperative mammographic examinations. Suspicious lesions were seen in 4 patients, and microcalcifications were identified in the fifth. The sixth patient had a normal xeromammogram. Pathological diagnosis was infiltrating ductal carcinoma in 5 patients and intraductal carcinoma in 1. Findings for lymph nodes were negative in 3 patients; 2 others had positive findings in one lymph node, and 1 had positive results in four lymph nodes. Five patients had a suspicious mass that was palpated on self-examination or by the patient's plastic surgeon, and the sixth patient had a routine screening mammogram. Two of 3 patients with positive lymph nodes received adjuvant chemotherapy. This report confirms the role of mammography as a screening tool in making the diagnosis of breast cancer in women who have undergone augmentation mammoplasty. The importance of self-examination and follow-up by the plastic surgeon is stressed. The data suggest that mammography remains an accurate method for detecting breast lesions.

Adult↗
PubMed1989

Studies on copper-zinc superoxide dismutase expression in developing human liver and kidney.

CuZn superoxide dismutase levels were found to be high in developing human kidney and liver compared to some other tissues including lung. In kidney, the enzyme was expressed in proximal and distal tubules, loop of Henle and collecting tubules and after 35 weeks of gestation it appeared to be distributed basally in proximal cells and luminally in distal cells. Glomerular structures were generally negative. CuZn superoxide dismutase was widely expressed in developing liver, with hepatocytes and bile duct epithelium demonstrating positivity. The low level of expression of CuZn superoxide dismutase in the glomerulus compared with the tubules was not expected since intrinsic glomerular cells demonstrate greater production of reactive oxygen species in response to some stimuli than do tubular cells. Expression of this enzyme may be determined by the need to generate hydrogen peroxide.

Cytosol↗
PubMed1989

Visceral leishmaniasis unresponsive to pentostam caused by Leishmania tropica in Kenya.

We report the characterization of 6 Leishmania tropica isolates from 2 patients with visceral leishmaniasis who were unresponsive to treatment with sodium stibogluconate. The Leishmania isolates, MHOM/KE/81/NLB-029A, -029XIB, and -029XIC and MHOM/KE/81/NLB-030I, -030B, and -030XXA, all from splenic aspirates, were characterized by cellulose acetate electrophoresis using 11 enzymes: malate dehydrogenase, malic enzyme, phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, superoxide dismutase, glutamate-oxaloacetate transaminase, adenylate kinase, nucleoside hydrolase, mannose phosphate isomerase, glucose phosphate isomerase, and phosphoglucomutase. Isozyme migration patterns were indistinguishable from those of 2 WHO reference strains of Leishmania tropica (MHOM/SU/60/LRC-L39, NLB-305 and MHOM/IQ/OO/LRC-L36, NLB-067). These are the first reported cases of visceral leishmaniasis (kala-azar) caused by L. tropica in Africa; these cases were refractory to sodium stibogluconate.

Animals↗
PubMed1989

Team physician #6. Surgical treatment of Achilles tendon rupture.

The ideal treatment of Achilles tendon ruptures has always been controversial. Nonoperative treatment has been criticized for its high rerupture rate and surgical treatment has been criticized for its high complication rate. This paper describes a surgical method of repair that can be used for acute or late ruptures, and has been associated with a low complication and rerupture rate.

Achilles Tendon↗
PubMed1988

Molecular aspects of sex determination in mice: an alternative model for the origin of the Sxr region.

Using a combination of in situ mapping and DNA analysis with recombinant DNA probes specific for the Sxr region of the mouse Y chromosome, we show that both the gene(s) controlling primary sex determination and the expression of the male-specific antigen H-Y (Tdy and Hya respectively) are located on the minute short arm of the mouse Y chromosome. We demonstrate that the H-Y- variant of Sxr (Sxr') arose by a partial deletion within the Sxr region and propose an alternative model for the generation of the original Sxr region.

Animals↗
PubMed1988

Survey of general practitioners' treatment of the discharging ear.

The prescribing habits of all (401) general practitioners in the North Staffordshire health district for the treatment of otorrhoea was ascertained by questionnaire; 301 (75%) responded. Of those, 198 (66%) would not give topical treatment when the tympanic membrane was perforated. Only 41 (14%) would give topical treatment in cases of discharging grommets. Although there is a theoretical risk of ototoxicity to aminoglycosides in topical preparations, this is the most effective medical treatment and is the standard teaching advocated in specialist textbooks and practised by otolaryngologists. The results of the survey suggest that there is undue concern about possible ototoxicity and a degree of confusion in the management of this common clinical condition.

Administration, Oral↗
PubMed1988

Screening for enteropathogenic Escherichia coli.

In an attempt to identify the prevalence of enteropathogenic Escherichia coli (EPEC) carriage and to minimize the chances of admitting a baby to the neonatal wards with unsuspected EPEC infection, 27,174 maternity patients admitted in labour and 4049 neonates admitted to the Special Care Baby Unit (SCBU) were screened for intestinal carriage of common EPEC serotypes. Two hundred and sixty-five (1%) maternity patients were positive, of whom 8 (3%) had diarrhoea. Of the babies born to these mothers, 10 (3.8%) were infected with EPEC and in each the serotype was the same as the mother's. Nine neonates (0.2%) admitted to the SCBU were also found to be infected with EPEC. Seven of the 19 babies (37%) had diarrhoea. Symptomatic mothers or babies were nursed in isolation. During the 8 year period under study no incidents of cross-infection with EPEC occurred.

Carrier State↗
PubMed1988

Extraintestinal salmonellosis.

Between 1969 and 1984, 6564 non-typhoid salmonella strains were isolated at the Liverpool Public Health Laboratory of which 194 (3.0%) were from extraintestinal sites. Blood (34%) and urine (32%) isolates accounted for two-thirds of these, with the remainder being recovered from pus and inflammatory tissue (23%), bone (5%), cerebrospinal fluid (5%) and sputum (3%). Certain serotypes tended to cause more invasive disease than others, i.e. Salmonella choleraesuis, S. dublin, S. london, S. virchow and S. panama: this association for S. london has not previously been described. The spectrum of disease caused by non-typhoid strains was broad. This survey confirms the importance of non-typhoid salmonellas as occasional causes of invasive disease and local sepsis outside the gastrointestinal tract.

Adolescent↗
PubMed1988

Molecular and cytogenetic evidence for the location of Tdy and Hya on the mouse Y chromosome short arm.

Using a combination of in situ mapping and DNA analysis with recombinant DNA probes specific for the Sxr region of the mouse Y chromosome, we show that both the gene(s) controlling sex determination and the expression of the male-specific antigen H-Y (Tdy and Hya, respectively) are located on the minute short arm of the mouse Y chromosome. We demonstrate that the H-Y- variant of Sxr (Sxr') arose by a partial deletion within the Sxr region. Also, we show that intrachromosomal recombination between the Y short arm and Sxr' can sometimes occur during male meiosis, restoring the deleted DNA sequences and resulting in an H-Y+ mouse (male 719 in this paper). Based on these results, we propose a model for the generation of the original Sxr region and the Sxr' and Sxr719 variants.

Animals↗
PubMed1988

The "treatment IND (investigational new drugs)": public policy considerations.

A major activity occupying the U.S. Food and Drug Administration for several years has been a rewrite of the FDA's IND and NDA regulations which govern the clinical testing of investigational new drugs and the process for subsequent market approval for those drug entities. In March of 1987, the FDA "reproposed" that portion of the 1983 IND rewrite dealing with the "treatment use" of investigational new drugs during the clinical testing phases of new drug development or during the period between the completion of clinical testing and NDA approval. The Treatment IND reproposal resulted in substantial controversy immediately following its publication in the Federal Register. This article compares the key features of the Treatment IND regulations as reproposed with those of the Final Rule and summarizes the major points of contention among the various interest groups affected. With its new Treatment IND regulations, the FDA appears to have placed itself squarely between competing interests and public policy considerations. The essential purpose and role of the FDA is to determine the inherent safety and effectiveness of new therapeutic medications. Debate on the Treatment IND regulations has raised a number of questions as to the regulations' own safety and efficacy in achieving that objective. It is likely the Treatment IND implementation will engender as much controversy as the regulations as originally reproposed.

Drug Evaluation↗