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Biomedical subjects

S Cohen

Publications and source records attributed to S Cohen.

At least 307 records · Page 17Linked to original sources
PubMed1995

Effect of haemorrhage on the power of low frequency blood pressure fluctuations in young spontaneously hypertensive rats.

1. Before the onset of hypertension low frequency (0.04-0.1 Hz) MAP fluctuations are reduced in SHR when compared to WKY. We studied the effect of haemorrhage under alpha1 blockade or angiotensin converting enzyme inhibition (CEI) on the power spectra (PS) of each strain. 2. MAP was recorded from the caudal artery in conscious, 1 month old SHR and WKY. Three groups of rats were studied. Group 1, acute 2 mL haemorrhage; groups 2 and 3, injection of prazosin (0.25-2.5 mg/kg) or captopril (0.5-4 mg/kg), followed by haemorrhage, as in group 1. The PS was divided into 3 frequency bands, 0.004-0.04, 0.04-0.07 and 0.07-0.1 Hz. 3. In SHR, although the baseline MAP levels were similar to those of WKY, the PS was significantly damped in each of the 3 frequency bands. 4. Haemorrhage induced a similar MAP fall in both strains accompanied by an increase in the slow MAP fluctuations. However, in SHR the PS response was significantly greater than in WKY. The biggest response was in the slowest (0.004-0.04 Hz) frequency band, 8.7 +/- 1.7 vs 1.5 +/- 0.4 times baseline levels, respectively. 5. The difference between the two strains in the PS response to haemorrhage was eliminated by alpha1 blockade. The exaggerated response observed in haemorrhaged, unblocked SHR was reduced in the 3 frequency bands. 6. Captopril reduced the PS response to haemorrhage in SHR to the level observed in WKY in all 3 frequency bands. 7. The enhanced amplification of the MAP fluctuations in haemorrhaged SHR may indicate that SHR requires greater recruitment of control mechanisms than WKY to maintain MAP at a similar level to WKY.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1995

Loss of reproductive competence at an earlier age in female rats exposed prenatally to ethanol.

Previous studies have shown that prenatal ethanol exposure can partially masculinize or defeminize neurobehavioral development of female rats. An early age of onset of anovulation is one of the primary characteristics of partial defeminization. Consequently, we examined the occurrence of anovulation in fetal alcohol-exposed (FAE) female rats at 2, 6, and 12 months of age using both vaginal cytology as well as wheel-running behavior. We assessed the ability of estrogen and progesterone to elicit proprioceptive behaviors and lordosis at 2 and 17 months of age. Female subjects were derived from Sprague-Dawley dams administered an ethanol liquid diet (35% ethanol-derived calories), a pair-fed isocaloric liquid diet, or fed lab chow from days 14 to 22 of gestation. Litter representatives were placed in a computer-monitored wheel-running apparatus under a 12-hr lighting schedule from 49 to 60 days of age. Vaginal smears were taken from littermates during this same period. This same procedure was conducted again from 180 to 196 and from 380 to 396 days of age, except that vaginal cytology was examined in the same animals immediately after wheel-running behavior was studied. At approximately 2 months of age, a normal cyclical pattern of wheel-running, characteristic of 4- to 5-day estrus cycles, was observed in all animals. No differences were detected in mean activity levels during the wheel-running period. This was accompanied by normal cyclic vaginal cytology and normal proprioceptive behaviors and lordosis. At 6 months of age, FAE females exhibited significantly reduced wheel-running.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1995

Effect of delayed specimen processing on cytomegalovirus antigenemia test results.

Blood samples held at either 4 degrees C or room temperature for 1 day had similar mean decreases in number of cytomegalovirus antigenemia-positive cells (52 to 55%) and similar false-negative test results (13 to 14%). After 2 days, samples held at 4 degrees C showed no further decline, whereas samples held at room temperature had a mean 81% decrease in positive cells, a 32% false-negative rate, and a more marked deterioration in cell morphology.

Antigens, Viral↗
PubMed1995

Psychological stress and susceptibility to upper respiratory infections.

The biologic plausibility of a link between psychological states and host resistance is discussed. Although there is substantial evidence for the association between psychological stress and both cellular and humoral immune response, these data do not necessarily suggest increased susceptibility to infectious agents among stressed persons. Epidemiologic and viral-challenge studies suggest that psychological stress is a risk factor for upper respiratory infections with the strongest evidence provided by recent well-controlled, prospective viral-challenge trials. However, there is still little direct evidence for the nature of neuroendocrine, immune, or behavioral pathways through which stress might alter susceptibility.

Acute Disease↗
PubMed1995

[Traumatic tricuspid insufficiency. Apropos of 2 cases].

The authors report two cases of tricuspid regurgitation by a ruptured anterior papillary muscle secondary to non-penetrating thoracic trauma. In the presence of suggestive clinical and electrocardiographic abnormalities (systolic murmur, right heart failure, right bundle branch block), echocardiography confirmed the tricuspid regurgitation, showed its mechanism and excluded any other intracardiac lesions. Tricuspid annuloplasty was performed in both cases because of the persistence of failure or degradation of the patient's clinical condition. Peroperative echocardiography was used to judge the quality of the surgical repair in both cases. Traumatic tricuspid regurgitation is a rare condition and the diagnosis is often delayed. Echocardiography is the investigation of choice and guides treatment which is essentially valvular repair in symptomatic patients.

Adult↗
PubMed1995

Health Promotion Schools of Excellence: a model program for Kentucky and the nation.

This article reviews the development and progress of an innovative, comprehensive school health project in the Jefferson County school district known as the Health Promotion Schools of Excellence (HPSE). This project features unique working relationships between public and private entities seeking a common goal: "A Healthier Community." The goals and development of HPSE have been formulated to coincide with the emerging directives of the Kentucky Education Reform Act (KERA) as well as the growing pressures to control health care costs through effective preventive measures. The results of testing following the first and second years of the project show an encouraging trend of improved physical fitness levels for all students (grades K-12) and improving levels of health knowledge and attitudes in elementary level children (grades 4-8) as well as school faculty and staff. These initial results, although encouraging, will only be meaningful if they translate over time into a healthier, more responsible cohort of adolescents and young adults when compared to their peers not involved in the project. The project, while only in its third year of development, has already been recognized at regional and national levels as a successful model of a comprehensive school health program. As the project continues and grows, the authors anticipate developing one of the nation's largest and most comprehensive longitudinal data bases of childhood and adolescent health information.

Adolescent↗
PubMed1995

Intraoperative spermatic venography reconsidered.

We review our most recent experience with varicocelectomy and post-ligation venography in 58 adolescents as followup to our previously reported series. A single injection venogram confirmed the completeness of varicocele ligation in 82% of cases while 2 or more injections were required in the remainder. Venography was not performed in 8 cases because of technical difficulties in 5 or surgeon choice in 3. The recurrence rate was 8.6% and was not statistically significant whether or not venography was performed (p = 0.86). Although intraoperative spermatic venography is technically simple and safe, in our series its efficacy in diminishing the recurrence rate after varicocelectomy was unproved.

Adolescent↗
PubMed1995

Investigation of benefits and costs of an ophthalmic outreach clinic in general practice.

BACKGROUND: With the advent of general practitioner fundholding, there has been growth in outreach clinics covering many specialties. The benefits and costs of this model of service provision are unclear. AIM: A pilot study aimed to evaluate an outreach model of ophthalmic care in terms of its impact on general practitioners, their use of secondary ophthalmology services, patients' views, and costs. METHOD: A prospective study, from April 1992 to March 1993, of the introduction of an ophthalmic outreach service in 17 general practices in London was undertaken. An ophthalmic outreach team, comprising an ophthalmic medical practitioner and an ophthalmic nurse, held clinics in the practices once a month. Referral rates to Edgware General Hospital ophthalmology outpatient department over one year from the study practices were compared with those from 17 control practices. General practitioners' assessments of the scheme and its impact on their knowledge and practice of ophthalmology were sought through a postal survey of all partners and interviews with one partner in each practice. Patient surveys were conducted using self-administered structured questionnaires. A costings exercise compared the outreach model with the conventional hospital ophthalmology outpatient clinic. RESULTS: Of 1309 patients seen by the outreach team in the study practices, 480 (37%) were referred to the ophthalmology outpatient department. The annual referral rate to this department from control practices was 9.5 per 10,000 registered patients compared with 3.8 per 10,000 registered patients from study practices. A total of 1187 patients were referred to the outpatient department from control practices. An increase in knowledge of ophthalmology was reported by 18 of 47 general practitioners (38%). Nineteen (40%) of 47 general practitioners took advantage of the opportunity for inservice training with the outreach team; they were more likely to change their routine practice for ophthalmic care or referral criteria for patients with cataracts or diabetes than those who did not attend for inservice training. The outreach scheme was popular with patients, for whom ease of access and familiarity of surroundings were major advantages. The cost per patient seen in the outreach clinics (48.09 pounds) was about three times the cost per patient seen in the outpatient department (15.71 pounds). CONCLUSION: The model of ophthalmic outreach care in this pilot study was popular with patients and general practitioners and appeared to act as an effective filter of demand for care in the hospital setting. However, the educational impact of the scheme was limited. Although the unit costs (per patient) of the outreach scheme compared unfavourably with those of conventional outpatient treatment, potential health gains from this more accessible model of care require further exploration.

Ambulatory Care Facilities↗
PubMed1994

Time to abandon Brussels' bid on patents.

After six years of debate, the European Commission's attempts to harmonize biotechnology legislation still face opposition over the patenting of genes. Recent legal experience suggests that its efforts are unnecessary.

Animals↗
PubMed1994

Isolated P2 rRNA promoters of Escherichia coli are strong promoters that are subject to stringent control.

Ribosomal RNA synthesis in Escherichia coli is under stringent control. The seven rRNA operons are highly conserved and are each transcribed from two tandem promoters, P1 and P2, which are located about 120 base-pairs apart. In exponentially growing cells the majority of the transcripts are initiated at the P1 promoters. The P1 promoters are highly regulated, and are under stringent as well as growth rate controls. Here we demonstrate that transcription from the rrnA P1 promoter diminishes P2 expression. In the absence of P1, the P2 promoter acts as a rather strong promoter. Insertion of a transcription terminator between P1 and P2 eliminates the inhibition of P2 by P1, suggesting that the physical movement of RNA polymerase originating at P1 and progressing along the P2 promoter is necessary for the interference process to take place. Similarly to P1, the solitary P2 promoter is subject to stringent control.

Base Sequence↗
PubMed1994

Epidermal growth factor and lipopolysaccharide activate Stat3 transcription factor in mouse liver.

Previous studies demonstrated that the intraperitoneal injection of epidermal growth factor (EGF) into mice resulted in the appearance, within minutes, of several tyrosine-phosphorylated proteins in liver nuclei. Two of these proteins have been identified as the transcription factors p91/p84 (Stat1 alpha/1 beta) (Ruff-Jamison, S., Chen, K., and Cohen, S. (1993) Science 261, 1733-1736). We have now identified, by Western blotting and immunoprecipitation, an additional EGF-modulated transcription factor, Stat3. We find that Stat3 is tyrosine-phosphorylated and present in mouse liver nuclei following either EGF or lipopolysaccharide administration. Gel shift analyses show that Stat3 is capable of specifically binding the SIE (a DNA sequence present in the c-fos promoter). Three active SIE binding complexes (SIF A, B, and C) exist in the nucleus after the administration of EGF: one complex that contains Stat3, one that contains Stat1, and a third complex that appears to contain both proteins. Only one active SIE binding complex, containing Stat3, was detected after the administration of lipopolysaccharide.

Animals↗
PubMed1994

Polymeric 6-aminoquinoline, an activated carbamate reagent for derivatization of amines and amino acids by high-performance liquid chromatography.

A new polymeric reagent containing the 6-aminoquinoline (6-AQ) tag was developed and applied for the off-line derivatization of amines and amino acids in high-performance liquid chromatography (HPLC). The synthesis and characterization of this polymeric reagent are described. An authentic external standard of a typical amine was synthesized and characterized for the determination of the derivatization efficiency. All amines had a derivatization efficiency higher than 50%; the derivatization of amino acids was performed under optimized phase-transfer catalysis reaction conditions. Derivatized amines and amino acids were separated under conventional reversed-phase conditions and determined by UV and FL detectors. To investigate the practical applications, this polymeric reagent was also used to derivatize protein hydrolysates.

Amines↗