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Biomedical subjects

D Cohen

Publications and source records attributed to D Cohen.

At least 199 records · Page 11Linked to original sources
PubMed1998

Fracture of the posterior body of the talus--the hidden fracture.

Fractures of the entire posterior process of the talus are rare and may be easily missed. Both the ankle joint and the subtalar joint are involved. This leads to malunion and early degenerative changes. We describe four patients with fractures of the posterior process of the talus which were initially missed. The patients were treated conservatively, and early mobilization or cast immobilization did not change the poor late results. The pitfalls in the diagnosis and imaging evaluation of such fractures are discussed.

Adult↗
PubMed1998

Antibiotic resistance pattern of enterotoxigenic Escherichia coli isolated from infants and young adults in Israel.

The aim of this study was to describe antibiotic resistance rates of enterotoxigenic Escherichia coli in Israel in order to facilitate the empirical choice of antibiotic treatment or prophylaxis for traveler's diarrhea and infantile diarrhea in our region. A total of 281 enterotoxigenic Escherichia coli isolates were tested: 144 from Bedouin infants and 137 from Israeli soldiers. Antibiotic-resistant isolates were prevalent in both groups, but higher resistance rates were found in the pediatric group. Strains producing heat-labile toxin showed higher resistance rates than strains producing heat-stable toxin. The results obtained in Israel preclude the use of many commonly used antibiotics for the treatment of traveler's diarrhea. Quinolones, however, are still effective.

Adolescent↗
PubMed1998

The phytoestrogen genistein reduces bone loss in short-term ovariectomized rats.

The incidence of fractures and of osteoporosis differs between Oriental and Western Caucasian women. This may depend, at least in part, on nutritional factors, including dissimilarities in dietary intake of phytoestrogens. To investigate this possibility, 2-month-old female rats were ovariectomized (OVX) or sham-operated (SHAM), fed a casein-based diet, injected daily with subcutaneous genistein (GEN), the most abundant and best characterized phytoestrogen, or vehicle (Veh) and killed 21 days after surgery. As expected, ovariectomy resulted in loss of bone mineral density (BMD) and in uterine atrophy. However, administration of 5 micrograms GEN per gram body weight (b.w.) ameliorated the ovariectomy-induced loss of BMD (189 +/- 2 mg/cm2 in OVX and 192 +/- 2 in OVX with 5 micrograms GEN/g b.w. per day; p < 0.05). One microgram GEN per gram body weight did not affect the BMD loss and the effect of the 5 micrograms and 25 micrograms GEN per gram body weight were statistically not different. A trend toward reduced uterine atrophy (21% reduction) was noted with the 25 micrograms GEN dose, but not with the 1 microgram and 5 micrograms doses. A separate experiment with 2 x 2 factorial design was conducted to elucidate the mechanism by which GEN ameliorates ovariectomy-induced bone loss. In this experiment, histomorphometry demonstrated a dramatic reduction in trabecular bone volume after ovariectomy (7.6 +/- 0.7% of total bone volume in SHAM-Veh vs 3.3 +/- 0.2% in OVX-Veh; p < 0.01) and less bone loss in OVX rats injected with 5 micrograms GEN per gram per day (3.3 +/- 0.2% of total bone volume in OVX-Veh vs 5.2 +/- 0.4% in OVX-GEN; p < 0.01). Administration of GEN was associated with higher bone formation rate per tissue volume and with a trend toward a higher number of osteoblasts per bone perimeter. The parameters of bone resorption were not affected by GEN. The concentration of serum osteocalcin and the urinary excretion of deoxypyridinoline provided corroborating results. Since production of proinflammatory cytokines is intimately involved in the pathogenesis of postmenopausal osteoporosis, the effect of GEN on lipopolysaccharide-induced in vitro production of Tumor necrosis factor-alpha (TNF alpha) was tested in monocytic cells from the same four rat groups. Production of TNF alpha was markedly elevated in OVX-Veh as compared with the SHAM-Veh rats, but this was blocked by GEN in the OVX rats. This study shows that GEN reduces both trabecular and compact bone loss after ovariectomy and that this protective effect differs from that of estrogen, since it depends on stimulation of bone formation rather than on suppression of bone resorption. Lack of action of GEN on uterine atrophy supports the possibility that this GEN dose affects target tissues via non-estrogenic mechanisms. Modulation of cytokine production may be involved in the effect of GEN on bone.

Amino Acids↗
PubMed1998

Elevated lipoprotein(a) levels and small apo(a) isoforms are compatible with longevity: evidence from a large population of French centenarians.

Epidemiological studies have shown lipoprotein(a) (Lp(a)) to be an independent risk factor for cardiovascular disease. Lp(a) is a cholesterol-rich, low-density lipoprotein (LDL)-like particle to which a large glycoprotein, apolipoprotein(a) (apo(a)) is attached. Plasma Lp(a) levels are highly genetically determined and influenced to a minor degree by environmental factors. In an effort to determine whether Lp(a) might be associated with longevity, we have evaluated Lp(a) levels and apo(a) isoform sizes in a population of French centenarians (n = 109) compared to a control group (n = 227). The mean age of centenarians was 101.5 +/- 2.4 years while the control group was 39.4 +/- 7.2 years. Plasma levels of total cholesterol and triglyceride were within the normal range in both centenarian and control subjects. Lp(a) levels were higher in centenarians (both male and female) than in the normolipidemic control group (mean Lp(a) level = 0.33 +/- 0.42 and 0.22 +/- 0.27 mg/ml, respectively, P < 0.005). The distribution of apo(a) isoforms was significantly shifted towards small isoform size in the centenarian population as compared to the controls (54.4 and 41.4% of isoforms < or = 27 kringles (kr), respectively, P = 0.04). Nonetheless, the apo(a) size distribution in centenarians did not entirely explain the high Lp(a) levels observed in this population. Factors other than apo(a) size, and which may be either genetic or environmental in nature, appear to contribute to the elevated plasma Lp(a) levels of our centenarian population. We conclude therefore that high plasma Lp(a) levels are compatible with longevity.

Adult↗
PubMed1998

Detection of enterotoxigenic Escherichia coli in stool specimens by polymerase chain reaction.

A polymerase chain reaction (PCR) protocol for rapid (7 h) detection of enterotoxigenic Escherichia coli (ETEC) is described. This protocol has been validated on 57 stool samples from young children by comparing it with the colony hybridization technique. A good agreement was found between the two methods with Cohen's kappa statistics of 0.87 and 0.79 for the detection of the heat-stable toxin (ST) and heat-labile toxin (LT), respectively. Of 26 samples positive for LT and 15 samples positive for ST by colony hybridization, 21 (81%) and 15 (100%) were also found to be positive for LT and ST by PCR, respectively. Only one sample identified as LT-negative by colony hybridization was found to be positive by PCR. However, 3 of 42 samples of ST-negative by colony hybridization were detected as positive by PCR. A reconstruction experiment revealed that PCR could detect LT-producing and ST-producing ETEC at minimal concentrations of 2.5 x 10(3) cfu and 2.5 x 10(2) cfu per gram of feces, respectively. These data indicate the possible use of this method for rapid identification of ETEC-associated diarrhea in clinical and epidemiological settings.

Bacterial Toxins↗
PubMed1998

Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium phage-type DT104 among salmonellae causing enteritis in Israel.

The relative frequency of salmonella strains isolated from hospitalized and non-hospitalized patients in Southern Israel changed during the period, 1994-6. Salmonella enterica serotype Typhimurium definitive phage-type 104 (DT104) appeared in Israel in 1994 and became the most prevalent strain in 1996. An outbreak of enteritis due to Salmonella enterica serotype Agona occurred in Israel, in October 1994 and lasted for 4 months. The relative frequency of Salmonella enterica serotype Enteritidis remained almost constant during these years, with seasonal fluctuations only. The importance of the increase in the prevalence of Typhimurium DT104 has been the epidemic spread of a multiresistant strain of R-type ACT (A, ampicillin; C, chloramphenicol; T, tetracycline) belonging to this phage-type. Since 1995 the frequency of Typhimurium DT104 isolates that possess, in addition to the above R-type, a chromosomally encoded resistance to the quinolone drug, nalidixic acid, increased tenfold. In 1996, 27% of the Typhimurium DT104 isolates were of R-type ACTN. S. Enteritidis exhibited over 95% susceptibility to at least eight of the most commonly used antibiotic drugs, and none of the isolates was resistant to quinolone or fluoroquinoline.

Bacteriophage Typing↗
PubMed1998

PSC-833, a frontier in modulation of P-glycoprotein mediated multidrug resistance.

The expression of drug efflux mechanisms by cancer cells during chemotherapy leads to multidrug resistance (MDR) and constitutes a major obstacle in the effective treatment of cancer. The most widely characterized drug effluxes pump is P-glycoprotein (P-gp) and efforts are being directed towards identifying agents that reverse P-gp mediated drug resistance. PSC-833 is a non-immunosuppressive cyclosporin derivative that potently and specifically inhibits P-gp. The current review focuses on the elucidation of the mechanism of action of PSC-833 as a potential MDR reversing agent, using syngeneic multidrug resistant sublines of MDA435 human breast adenocarcinoma cell line that express increasing levels of P-gp. In vitro experiments indicate that PSC-833 interacts directly with P-gp with high affinity and probably interferes with the ATPase activity of P-gp. Studies in multidrug resistant tumor models confirm P-gp as the in vivo target of PSC-833 and demonstrate the ability of PSC-833 to reverse MDR leukemias and solid tumors in mice. Presently, PSC-833 is being evaluated in the clinic.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Culture, social organization, and patterns of violence.

Traditional social theorizing holds that strong and cohesive family, community, and religious institutions rein in violence. However, in cultures where certain types of violence are condoned, this should not be true. Specifically, in the U.S. South and West, where culture-of-honor traditions persist, greater social organization should be associated with more violence. This pattern was confirmed in examinations of argument-related homicide rates (Study 1); mass consumption patterns for violence in entertainment, recreation, and vocational pursuits (Study 2); and voting patterns of political elites on gun control and national defense issues (Study 3). Across the 3 studies, social organization was associated with effects in the South and West opposite of what they were in the North. Implications for general theories of cultural evolution, suggesting a cycle in the way societies crystallize and change, are discussed.

Adolescent↗
PubMed1998

Middle ear laser office ventilation (LOV) with a CO2 laser flashscanner.

BACKGROUND: Laser assisted ventilation of the middle ear with a defocused laser beam has been performed on adults in an office setting without anesthesia. OBJECTIVE: The purpose of this study was to evaluate the efficacy and safety of a highly controlled, char-free CO2 flashscanner technology for the ventilation of the middle ear in young children, at this stage under general anesthesia, and later without anesthesia. METHODS: A CO2 flashscanning laser, in conjunction with a micromanipulator, was used on 21 SOM patients ages 3-7 years old, with followup at 2 months. Operating time is approximately 5 minutes. RESULTS: Postoperative results show average patency of 2-3 weeks without adverse effects. Of the treated patients, 53% did not require a second treatment, whereas 47% still suffered from otitis media and needed a second treatment. CONCLUSION: The CO2 flashscanner laser technology is effective and safe for middle ear ventilation and provides excellent control of the perforation diameter. It is already being performed in an office setting with sedation on a limited basis with very promising preliminary results. Based on the current study and on 70 additional cases with longer interval followup, we anticipate the office technique to become widely used in the future.

Ambulatory Surgical Procedures↗
PubMed1998

An exploration of GPs' use of MRI: a critical incident study.

BACKGROUND: Direct access to Magnetic Resonance Imaging (MRI) is becoming available to GPs in the UK, offering major benefits for the improved diagnosis and management of certain clinical conditions. Variations in usage of this service may be large, and effective locally produced guidelines are not currently available. The Department of General Practice is conducting a research programme to develop and evaluate methods to optimize MRI use by GPs. OBJECTIVES: We aimed to describe the current use of MRI by GPs in South Glamorgan; to summarize their reasons for requesting MRI; and to produce criteria to assess the appropriateness of magnetic resonance (MR) scan requests. METHODS: Using the critical incident technique, 25 GPs were interviewed about recent scans requested for patients with knee and lumbar spine complaints. A local panel of primary and secondary care doctors was convened to develop criteria for assessing MR scan requests. RESULTS: Sixty-two scan requests were discussed. Doctors' reasons for requesting MR scans were identified and classified. Reasons for requests included personal, contextual and biomedical variables. Fifteen patients (24%) were managed in primary care following MRI when otherwise they would have been referred. When referrals were made, GPs felt able to reinforce the request and occasionally to direct the patient somewhere more appropriate. The panel reviewed the interview data to produce objective criteria to assess scan requests. The criteria reflect the relative importance of non-biomedical variables in the decision to request MRI. CONCLUSION: The study identified those reasons which are important to GPs when requesting MR scans and the impact of this new technology upon patient management. Interview data have been used to inform locally developed consensus criteria, which will be made available as practice guidelines as the research programme progresses.

Aged↗
PubMed1998

Isolation and characterization of the lower portion of the thin limb of Henle in primary culture.

To further characterize cells of the lower portion of the thin limb of Henle (TLH1p) under defined conditions in vitro, we developed a technique to enrich this cell population in suspension. TLH1p cells were isolated by enzymatic digestion of rat inner medulla, elimination of collecting ducts by lectin-coated beads, and differential centrifugation. Immunohistochemical staining of primary cultures of TLH1p cells with various markers revealed the preparations to be > 90% pure. The hormonal stimulation pattern of PGE2 and cAMP production by arginine vasopressin, angiotensin II, and dopamine in the isolated cells also argued against significant contamination by other cell types. Staining with an antibody against the aquaporin-1 water channel showed the distribution of cells from the ascending and descending limbs to be approximately equal in the isolated population. This technique allows the enrichment of cells from the lower portion of the thin limb of Henle in suspension to a very high degree of purity with the option to start primary cultures. Because these segments of the tubular system in particular are relatively inaccessible for microdissection, the presented method renders the possibility of addressing new questions regarding these tubular segments under defined conditions in vitro.

Animals↗
PubMed1998

Homicide-suicide in older persons.

OBJECTIVE: The objective of this study was to determine the annual incidence of homicide-suicide and to compare patterns and antecedents in old and young spousal/consortial cases. METHODS: Homicide-suicide cases were ascertained in four medical examiner districts covering seven entire Florida counties from 1988 to 1994. The districts were chosen to determine rates in two regions of Florida, comparable in size of the total population and proportion of older persons. Annual homicide-suicide incidence rates per 100,000 population and homicide-suicides as a percentage of total homicides and total suicides separately were calculated by age group and Florida region. Complete medical examiner files were obtained, and 160 variables were coded from medical examiner reports to compare features and clinical characteristics by age and region. RESULTS: Annual incidence rates ranged from 0.3 to 0.7 per 100,000 for persons under age 55 and from 0.4 to 0.9 per 100,000 for persons age 55 and older, with higher rates in the older group every year but two. Cases of spousal/consortial homicide-suicide were the most common in both age groups. The younger couples in both regions were comparable, except for racial composition, but the older couples differed. West central Florida couples were in their seventies, Caucasian, usually married, and both in poor health; and there were indications of depression or alcohol abuse in half the perpetrators. Two-thirds of the southeastern Florida couples were Hispanic; there was a mean age difference of 18 years between perpetrators and victims; and verbal discord, physical violence, and separation were prominent antecedents. CONCLUSIONS: The base rate for homicide-suicide in both age groups was higher than that reported in previous studies. Spousal/consortial homicide-suicides were the dominant form, and although psychopathology was strongly implicated, homicide-suicides are violent lethal acts resulting from additive or multiplicative effects of diathesis, including culture, and stressful experiences.

Age Distribution↗
PubMed1998

Affect and marital adjustment in women's rating of dyspareunic pain.

OBJECTIVE: To investigate the extent to which depressive symptomatology, anxiety, and marital adjustment mediate pain ratings in women suffering from dyspareunia. METHOD: Seventy-six women with dyspareunia were administered the depression and anxiety scales of Derogatis's Brief Symptom Inventory and the McGill Pain Questionnaire. They also underwent a manual-visual gynecological examination, an ultrasound, and a colposcopy in an attempt to identify potential evidence and type of organicity. RESULTS: Depressive symptomatology, anxiety, and marital adjustment together accounted for a significant amount of the variance in pain ratings, although only anxiety and marital adjustment were independent predictors of pain ratings in the entire group of women with dyspareunia. When multiple regression analyses were then applied to different diagnostic subgroups of dyspareunia, the independent predictors of pain rating varied depending on the findings from the gynecological examinations. CONCLUSION: Affect and marital adjustment appear to be significant predictors of dyspareunic pain rating, although the independent contribution of psychosocial variables may vary depending on the presence and type of organic findings.

Adaptation, Psychological↗
PubMed1998

Cerebral blood flow velocity decreases during cognitive stimulation in Huntington's disease.

OBJECTIVE: To examine whether activation of cerebral blood flow velocity during cognitive stimulation, as measured by transcranial Doppler ultrasonography (TCD), is altered in patients with Huntington's Disease (HD). BACKGROUND: Previous research suggests that resting cerebral blood flow in symptomatic and asymptomatic HD patients is reduced from expected premorbid levels. The effects of cognitive activation on this relative hypoperfusion in HD has not been studied extensively. METHODS: We measured TCD flow velocity during rest and cognitive testing with the Porteus Maze Test and the Trails Test in 12 normal control subjects and 10 gene-positive HD patients. Percent change (i.e., flow during testing/resting) of flow velocity in the anterior and middle cerebral arteries were compared between groups. Correlations among percent flow velocity change, a disability rating scale, and cognitive test scores were calculated. RESULTS: In control subjects, anterior cerebral artery flow velocity and middle cerebral artery velocity increased during cognitive testing (p=0.001). HD patients showed a smaller blood flow velocity increase in the anterior cerebral arteries during the Porteus Maze Test (p < 0.001) and the Trails Test, Part B (p < 0.001). In the left anterior cerebral artery, flow velocity fell an average of 4.2% below resting baseline levels during the Porteus Maze Test, and 1.2% below resting levels during the Trails Test. The magnitude of the cerebral blood flow velocity changes in the anterior cerebral artery correlated with a number of cognitive test scores and with a rating scale of functional disability. In addition, logistic regression was able to discriminate the HD patients from the control group based on blood flow velocity changes (p=0.0025). When HD patients were divided into more (i.e., HD with chorea; n=4) and less impaired (i.e., without chorea; n=6) groups, both showed significant decreases in left anterior cerebral artery flow velocity during visual spatial executive cognition testing compared with control subjects. CONCLUSIONS: These results suggest that activation of visual spatial executive functions cause decreased flow velocity in the anterior cerebral artery, but not the middle cerebral artery, in HD patients. These changes are related to test performance and functional capabilities.

Activities of Daily Living↗