Search PubMed⌕ Search

Biomedical subjects

B Stern

Publications and source records attributed to B Stern.

At least 37 records · Page 2Linked to original sources
PubMed1989

Respiratory health effects associated with ambient sulfates and ozone in two rural Canadian communities.

A cross-sectional epidemiological study investigating the respiratory health of children in two Canadian communities was conducted in 1983-1984 in Tillsonburg, Ontario, located in a region of moderately elevated concentrations of transported air pollutants, and in Portage la Prairie, Manitoba, situated in a low pollution area. There were no significant local sources of industrial emissions in either community. Seven hundred and thirty-five children aged 7-12 were studied in the first town and 895 in the second. Respiratory health was assessed by the measurement of the forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) of each child, and by evaluation of the child's respiratory symptoms and illnesses using a parent-completed questionnaire. Sulfur dioxide (SO2), sulfate, and particulate nitrate levels were significantly higher in Tillsonburg than in Portage la Prairie (P less than 0.05), but nitrogen dioxide (NO2) and inhalable particles (PM10) differed little between the communities. Historical data in the vicinity of Tillsonburg indicated that average annual levels of sulfates, total nitrates, and ozone (O3) did not vary markedly in the 9-year period preceding the study. The results show that Tillsonburg children had statistically significant (P less than 0.001) lower levels of 2% for FVC and 1.7% for FEV1.0 as compared with children in Portage la Prairie. These differences could not be explained by parental smoking or education, the use of gas cooking or wood heating fuels, pollution levels on the day of testing, or differences in age, sex, height, or weight. The differences persisted when children with cough with phlegm, asthma, wheeze, inhalant allergies, or hospitalization before age 2 for a chest illness were excluded from analysis. With the exception of inhalant allergies, which occurred more frequently in Tillsonburg children, the prevalence of chronic respiratory symptoms and illnesses was similar in the two communities.

Air Pollutants↗
PubMed1989

Acute lung function responses to ambient acid aerosol exposures in children.

We examined the relationship between lung function changes and ambient acid aerosol episodes in children attending a residential summer camp. Young females (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air quality measurements were performed on site and four distinct acid aerosol episodes were observed during the 41-day study. The maximum values observed during the 41-day study were: O3 at 143 ppb; H2SO4 at 47.7 micrograms/m3; and [H+] at 550 nmole/m3. Maximum decrements of 3.5 and 7% for FEV1 and PEF, respectively, were observed to be associated with the air pollution episodes. There was some evidence of a differential lung function response to the episodes where children with a positive response to a methacholine challenge had larger decrements compared to their nonresponsive counterparts.

Acid Rain↗
PubMed1989

Evolution of the DNA invertase Gin of phage Mu and related site-specific recombination proteins.

The relationship between site-specific recombination enzymes has been studied by computer analysis of nucleotide and amino acid sequences. A phylogenetic tree for two types of these enzymes has been constructed. DNA resolvases of Tn3-related transposable elements and DNA invertases form a superfamily which can be divided into four families of resolvases and one family of invertases comprising the Gin, Cin, Pin and Hin proteins. The DNA invertase genes descend from the tnpR branch that is represented by Tn917. Although TnpR 917 and Gin are almost 50% identical in their amino acid sequence, no gin-complementing activity of Tn917 could be measured. Within the family of DNA invertases, Gin and Pin are the closest relatives. The degree of sequence relatedness of the various invertases compared to Gin correlates with the biological relatedness tested in a gin complementation assay. A relationship between the inversion enzymes FimB and FimE and the super-family of site-specific recombinases could not be detected by these methods.

Bacteriophages↗
PubMed1988

Effects of omega-3 fish oils on lipid metabolism, glycemic control, and blood pressure in type II diabetic patients.

We investigated the effects of omega-3 fish oil (FO) supplementation on lipid metabolism, glycemic control, and blood pressure (BP) in patients with type II diabetes mellitus. In 22 diabetic patients without overt hyperlipidemia, serum triglyceride, total cholesterol, high density lipoprotein (HDL)-cholesterol, HDL2-cholesterol, HDL3-cholesterol, and apolipoprotein A-I (apo A-I) levels did not change during omega-3 FO supplementation for 8 weeks. The mean serum apo B concentration increased significantly [baseline, 2.56 +/- 0.11 (+/- SEM) mmol/L; 4 weeks, 2.82 +/- 0.13 mmol/L; 8 weeks, 2.80 +/- 0.13 mmol/L; P less than 0.01]. The mean plasma postheparin lipoprotein lipase activity increased transiently during the fourth week (baseline, 168 +/- 17 U/mL; 4 weeks, 182 +/- 18 U/mL; P less than 0.05), whereas postheparin hepatic triglyceride lipase activity did not change. Glycemic control worsened transiently during the fourth week, (baseline, 7.7 +/- 0.4%; 4 weeks, 8.4 +/- 0.3%; P less than 0.05). Both systolic and diastolic BP decreased significantly throughout the study (systolic BP: baseline, 142 +/- 5 mm Hg; 8 weeks, 128 +/- 5 mm Hg; diastolic BP: baseline, 88 +/- 4 mm Hg; 8 weeks, 80 +/- 3 mm Hg; P less than 0.01). These findings suggest that in type II diabetics without overt hyperlipidemia, omega-3 FO supplementation does not improve either the glycemic control or serum lipids, and it is associated with a potentially detrimental rise in serum apo B concentrations. Until more information is available, use of such supplementation should be discouraged.

Apolipoproteins↗
PubMed1986

Association between carcinogenic potency and tumor pathology in rodent carcinogenesis bioassays.

Carcinogenic potency (TD50) estimated from the results of 88 NCI/NTP carcinogenesis bioassays was examined by common target sites in rats and mice. Other indicators of a chemical's hazard were investigated, including whether tumors were induced at more than one site in a single sex-species group of test animals, whether tumors may have caused the death of the animal or were found at sacrifice, and whether metastases of induced tumors occurred. These hazard indicators are sometimes interrelated; however, the potency (TD50) values of chemicals which are hazardous by each of these measures spanned a wide range. Carcinogens which caused some type of fatal tumor were more likely than other carcinogens to cause tumors in multiple organ sites and multiple sex-species groups. Since these other hazard indicators were not related to carcinogenic potency, they should be included along with potency estimates such as the TD50 in summarizing the potential dangers of human exposures to a carcinogen and in comparisons of hazard among carcinogens.

Animals↗
PubMed1986

DNA inversion in bacteriophage Mu: characterization of the inversion site.

Gin-mediated site-specific recombination promotes inversion of the G segment of phage Mu. The crossover takes place between two 34 bp-long inverted repeat sequences flanking the G segment. We have characterized the inversion site, the target for the site-specific recombination mechanism. An artificial invertible segment was constructed which consists of parts of the invertible segments of Mu and phage P1, which in this respect are largely homologous. Upon inversion of this hybrid segment the crossover site could be located, by DNA sequencing, in the ACCT sequence of the centre of symmetry in the inverted repeat in Mu. The hybrid Mu-P1 segment inverts at a lower frequency than its parental invertible segments probably because of the mismatches between the inverted repeats of Mu and P1. This suggests that base pairing between the inverted repeats is an intermediate step in recombination. Plasmids with subcloned G segments lacking the adjacent beta region of Mu or the corresponding region in P7, a relative of P1, are deficient in inversion. By analysis through site-specific mutagenesis of Mu DNA, an enhancer element with multiple recognition sites was identified which is necessary for efficient inversion. This component of the inversion site was located in a 170 bp segment within the Mu beta region, 30 bp to the right of the inverted repeat sequence, but can be separated from the crossover site by a 1200 bp insertion without losing its effect.

Bacteriophage mu↗
PubMed1985

Neuropsychological outcome during late stage of recovery from brain injury: a proposal.

The neuropsychological outcome of Cranio-Cerebral Injury changes with time. This change may be best regarded as a specific effect/general effects ratio which lowers over time. The specific effects refer to disorders of information, recognition and symbolization. The present paper describes the general effects of brain injury. We will describe the lowered capacity of the cognitive system, which results in disorders of different aspects of concept formation and utilization (i.e. disorders of information processing).

Brain Injuries↗
PubMed1985

The Rey-Osterrieth Complex as a diagnostic measure of neuropsychological outcome of brain injury.

The Rey-Osterrieth Complex was devised to investigate perceptual organization and visual memory in brain-damaged patients. Osterrieth analyzed the patient's method of procedure as well as his specific copying errors, but the test is most commonly regarded as a measure of visual memory. In our work with traumatically brain-injured patients we found the Rey-Osterrieth Complex useful as a high load examiner of disorders of cognitive process. In our application of the test the drawing quality in the copy session is seen as being related to the kind of disorder, while the neuropsychological deficit is emphasized by the drawing quality in the memory session. The present paper is concerned with different thinking disorders as they are expressed in both the copy and memory parts of the Rey-Osterrieth Complex.

Adult↗
PubMed1985

On the use of dreams as a means of diagnosis of brain-injured patients.

In our psychotherapeutic work with brain injured patients it has become apparent that there exists a divergence between the two modes of expression with which the patient reflects his inner truth. In contrast to the patient's conscious self-perception, which is usually distorted by his cognitive deficits and by his defense mechanisms, the dream--the unconscious, uncovers another reality. The present paper cites a repeated pattern of initial dreams and an attempt is made to understand its diagnostic and prognostic meaning.

Brain Injuries↗
PubMed1985

Day Center experience in rehabilitation of craniocerebral injured patients.

The Day Center for head-injured patients specialises in treating patients at later stages following brain trauma. The goal of therapy is social reintegration as measured by the quality of family and social life and by actual occupational status. At this later stage, a year or more since injury, the cognitive and behavioral aspects of brain damage determine the outcome of rehabilitation. The therapy aims at preserving as well as improving patients' overall performance including family life and therefore their families are treated as well. As the patients are not hospitalised at this stage, the asset of this model is that it constitutes an arresting factor in preventing regressive attitudes acquired during hospitalisation which is a sheltered framework. The Day Center System encourages the patients to cope "in vivo" with reality, while the therapy given strives at providing them with the instruments needed for coping in actual life situations. We present here our experience in 38 patients admitted consecutively during the course of a year. The results show that the therapeutic milieu was of great help in preserving as well as improvement patients' performance; furthermore, it is evident that some improvement was achieved even after several years post trauma.

Adolescent↗
PubMed1984

Endocrine comparison of obese menstruating and amenorrheic women.

10 examine the relationship between obesity and chronic anovulation, we compared basal serum LH, FSH, and PRL levels, determined at 20-min intervals, and basal C21 [progesterone, 17- hydroxyprogesterone , pregnenolone, 17-hydroxypregnenolone ( 17Pe ), and cortisol], C19 [testosterone (T), delta 4-androstenedione (A), and dehydroepiandrosterone] and C18 (estrone and estradiol) steroid hormone concentrations measured at 1- to 2-h intervals for a 24-h period in five normal weight cycling women (NC) and in two groups of weight-matched obese women. Five of the obese women were regularly cycling (OC), and six were amenorrheic (OA). Sex hormone-binding globulin (SHBG) and non-SHBG-bound T and estradiol concentrations were also measured in each woman. Compared to NC women, OC women had normal basal protein and steroid hormone concentrations, except for reduced 17Pe levels (P less than 0.05). Mean SHBG concentrations were reduced by approximately 30%, and non-SHBG-bound T was increased by 70%, although the differences were not significant. In addition, when six precursors of testosterone (pregnenolone, 17Pe , dehydroepiandrosterone, progesterone, 17-hydroxyprogesterone, and A) were considered together as a group and the data analyzed by the kappa 2 test, a reduction in basal levels of these precursors was found in OC women relative to those in NC women (P less than 0.005). In OA women, mean concentrations of SHBG were markedly reduced and those of total T, A, estrone, and non-SHBG-bound T were significantly increased compared to those in both NC and OC women. Mean 24-h concentrations of LH tended to be greatest and FSH lowest in this group, but were not significantly different from those in the other groups. The mean LH pulse frequency was significantly greater in OA than in OC women (P less than 0.05). Mean 24-h PRL and cortisol levels were also reduced in OA women relative to those in NC women. These data suggest the possibility of a compensatory decline in total T production in OC women in an attempt to maintain normal hormonal homeostasis; as a consequence, ovulation continues in a cyclic fashion. In OA women, such compensatory mechanisms are no longer operative. Instead, a central and/or peripheral defect, resulting in overproduction of androgen, may also exist and lead to anovulation in OA women. In conclusion, our data imply that obesity is not a primary factor causing chronic anovulation. However, obesity may aggravate an already existing subtle defect in some women and result in amenorrhea.

Adult↗
PubMed1983

Calcium transport and Ca2+-ATPase activity in ram spermatozoa plasma membrane vesicles.

Plasma membrane vesicles, isolated from ejaculated ram sperm, were found to contain Ca2+-activated Mg2+-ATPase and Ca2+ transport activities. Membrane vesicles that were exposed to oxalate as a Ca2+-trapping agent accumulated Ca2+ in the presence of Mg2+ and ATP. The Vmax for Ca2+ uptake was 33 nmol/mg protein per h, and the Km values for Ca2+ and ATP were 2.5 microM and 45 microM, respectively. 1 microM of the Ca2+ ionophore A23187, added initially, completely inhibited net Ca2+ uptake and, if added later, caused the release of Ca2+ previously accumulated. A Ca2+-activated ATPase was present in the same membrane vesicles which had a Vmax of 1.5 mumol/mg protein per h at free Ca2+ concentration of 10 microM. This Ca2+-ATPase had Km values of 4.5 microM and 110 microM for Ca2+ and ATP, respectively. This kinetic parameter was similar to that observed for uptake of Ca2+ by the vesicles. The Ca2+-ATPase activity was insensitive to ouabain. Both Ca2+ transport and Ca2+-ATPase activity were inhibited by the flavonoid quercetin. Thus, ram spermatozoa plasma membranes have both a Ca2+ transport activity and a Ca2+-stimulated ATPase activity with similar substrate affinities and specificities and similar sensitivity to quercetin.

Animals↗
PubMed1980

Intervention study in high school students with elevated blood pressures. Dietary experiment with polyunsaturated fatty acids.

A blood pressure-lowering effect of increased prostaglandin synthesis via polyunsaturated fatty acids has been demonstrated in animal experiments. To our knowledge, for the first time an attempt was made to lower elevated blood pressures in adolescents (age 15-18 years) through a diet enriched in polyunsaturated fatty acids. This community-based dietary trial involved 30 students in the diet group and 20 students in the control group without any dietary intervention. Within 6 weeks the systolic blood pressure decreased by almost 11 mm Hg in the diet group and by 6 mm Hg in the control group. Diastolic blood pressure fell by 2 and 1 mm Hg, respectively. The effect on blood pressure was markedly different in normal weight adolescents. Systolic blood pressure in the diet group decreased by 14 mm Hg but only by 5 mm Hg in the control group. Diastolic blood pressure levels fell by 4 mm Hg in the diet group and increased by 4 mm Hg in the control group. Unfortunately, the numbers in these two comparison groups were rather small. The majority (70%) of adolescents with high blood pressure was overweight (greater than or equal to 20% above normal weight). However, for the small group of normal weight adolescents, the diet enriched with polyunsaturated fatty acids may be suitable to reduce elevated blood pressure levels.

Adolescent↗