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Biomedical subjects

D Bennett

Publications and source records attributed to D Bennett.

At least 235 records · Page 13Linked to original sources
PubMed1987

Piracetam and dyslexia: effects on reading tests.

Previous research has suggested that dyslexics treated with piracetam have shown improvements in reading skills, verbal memory and verbal conceptualizing ability, feature analysis, and processing of letter-like stimuli. Two hundred twenty-five dyslexic children between the ages of 7 years 6 months and 12 years 11 months whose reading skills were significantly below their intellectual capacity were enrolled in a multicenter, 36-week, double-blind, placebo-controlled study. Children of below average intelligence, with abnormal findings on audiologic, ophthalmologic, neurologic, psychiatric, and physical examinations, who were emotionally disturbed or educationally deprived and who had recently been treated with psychoactive medication were excluded from the trial. Piracetam was well tolerated, with no serious adverse clinical or laboratory effects reported. Piracetam-treated children showed significant improvements in reading ability (Gray Oral Reading Test) and reading comprehension (Gilmore Oral Reading Test). Treatment effects were evident after 12 weeks and were sustained for the total period (36 weeks).

Child↗
PubMed1987

C-reactive protein in dogs.

Serum concentrations of C-reactive protein (CRP) in dogs with various diseases or undergoing various procedures were measured by specific immunoassay. In 20 healthy dogs from various sources, values were all less than 5 mg/L, but in 22 healthy dogs from a single source, values ranged from less than 5 mg/L in 14 dogs and from 8 to 67 mg/L in 8 dogs. Increased concentrations of serum CRP were attained 24 hours after injection of casein (n = 9; median 188 mg/L), ovariohysterectomy (n = 11; median, 144 mg/L), or elective, nonacute orthopedic surgery (n = 10; median, 83 mg/L). After inoculation of Leptospira interrogans serovar canicola (n = 5), the behavior of serum CRP as an acute-phase reactant provided a sensitive and precise objective reflection of in vivo response. The CRP concentration in random single-serum samples from 73 dogs with other inflammatory and noninflammatory disorders ranged from normal (less than 5 mg/L) to 246 mg/L and generally correlated with the extent and activity of disease.

Animals↗
PubMed1986

Usefulness of noninvasive Doppler measurement of ascending aortic blood velocity and acceleration in detecting impairment of the left ventricular functional response to exercise three weeks after acute myocardial infarction.

Left ventricular (LV) function was assessed by Doppler ultrasound measurement of ascending aortic blood velocity and maximal acceleration in 165 patients 3 to 4 weeks after acute myocardial infarction (AMI); all were undergoing routine 12-lead electrocardiogram exercise stress testing. Patients were grouped according to electrocardiographic stress test response; a positive response was defined as at least 1 mm of ST-segment depression in any lead. The Doppler velocity signal yielded 3 variables of interest: peak velocity, maximal acceleration (an index of inotropic state) and the systolic velocity integral (an index of stroke volume). All 3 Doppler ejection variables were significantly lower at peak exercise in patients with a positive electrocardiographic stress test response than in those with negative response, with maximal acceleration showing the most significance (p less than or equal to 0.001). Coronary angiography was performed in 63 of the 67 patients with positive responses, and patients were separated into 2 groups according to extent of coronary artery disease (CAD): 1- and 2-vessel or 3-vessel CAD. Peak velocity and maximal acceleration were significantly lower in patients with 3-vessel CAD than in those with 1- and 2-vessel CAD (p less than or equal to 0.01 and p less than or equal to 0.01). Discriminant analysis showed maximal acceleration and peak velocity values at peak exercise to be 65% predictive of 3-vessel CAD, onset time to ST-segment depression was 74% predictive and the combination of Doppler and electrocardiographic variables increased 3-vessel CAD predictive value to 80%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Learning deficits occur in young mice following transfer of immunity from senescent mice.

The extent to which immune processes contribute to senescence-related neurological/behavioral impairment was examined using an adoptive transfer procedure. C57BL/6 mice aged 22 to 24 months showed impaired ability for acquisition of an active avoidance response when compared with younger mice aged 3 months. An immunofluorescence assay of the sera of these mice indicated that only sera from the senescent mice reacted with brain antigen. When tested three months following irradiation and receipt of bone marrow/spleen cell suspensions from senescent mice, young mice showed senescence-like serum-brain reactivity and declines in their abilities to acquire learning. Young control mice receiving cell suspensions from age-matched donors showed no evidence of serum-brain reactivity or learning deficits, suggesting that impaired learning was related to acquisition of aged immunity and not a nonspecific effect of the transfer procedure. These findings indicate that immune processes may be involved in the etiology of senescence-related neurological/behavioral dysfunctions.

Aging↗
PubMed1986

A synovial amidase acting on tissue kallikrein-selective substrate in clinical and experimental arthritis.

Increased levels of amidase acting on a tissue-kallikrein selective substrate, Val.Leu.Arg.pNA, with an activity optimum at pH9, were detected in blood-free inflamed tissues from adjuvant arthritic rats (p less than 0.01). The component of this activity resistant to inhibition by soybean trypsin inhibitor (SBTI) also greatly increased (p less than 0.05). Both the SBTI-sensitive and SBTI-resistant components were inhibited by aprotinin (93% and 72% respectively). Kallikrein-like amidase also increased in inflamed synovia from seropositive rheumatoid, and osteoarthritic dogs when compared with healthy canine synovia. This increase was parallelled by an increase in kinin-forming enzyme which was also measured in rheumatoid and healthy animals and this activity was inhibited 72% by aprotinin. Total kallikrein-like amidase also increased 989% (p less than 0.05) in synovia from seropositive rheumatoid human patients, compared with healthy synovial tissue. Evidence is presented indicating that the origin of this enzymic activity may be plasma kallikrein.

Amidohydrolases↗
PubMed1986

The influence of genetic background and the homologous chromosome 17 on t-haplotype transmission ratio distortion in mice.

Transmission ratio distortion is a characteristic of complete t-haplotypes, such that heterozygous males preferentially transmit the t-haplotype bearing chromosome 17 to the majority of their progeny. At least two genes contained within the t-haplotype have been identified as being required for such high transmission ratios. In this study we examine the effects of the genetic background and the chromosome homologous to the t-haplotype on transmission ratio distortion. We use two different congenic lines: BTBRTF/Nev.Ttf/t12, in which the t12 haplotype has a transmission ratio of 52%, and C3H/DiSn.Ttf/t12, in which the t12 haplotype has a transmission ratio of 99%. By intercrossing these two strains to produce reciprocal F1 and F2 generations, we have isolated the effects of the homologous chromosome 17 from the effects of the genetic background. We demonstrate that both the homologous chromosome and the genetic background have profound effects on t-haplotype transmission ratio distortion. Furthermore, it is evident that the t-haplotype transmission ratio behaves as a quantitative character rather than an intrinsic property of t-haplotypes.

Analysis of Variance↗
PubMed1986

OSHA work-practice guidelines for personnel dealing with cytotoxic (antineoplastic) drugs. Occupational Safety and Health Administration.

Work-practice guidelines for personnel dealing with cytotoxic drugs (CDs) are presented. Current practices in the preparation, storage, administration, and disposal of CDs may expose pharmacists, nurses, physicians, and other health-care workers to high environmental levels of these drugs. OSHA has developed these guidelines to protect health-care workers from unnecessary exposure to CDs. A brief summary of the short-term and long-term hazards known to be associated with these drugs is presented. The risks to workers handling CDs are a combined result of the drugs' inherent toxicity and the extent to which workers are directly exposed to CDs via inhalation, absorption, and ingestion. Work-practice guidelines that can limit the exposure of workers to CDs and the equipment necessary to carry out these practices properly are described.

Antineoplastic Agents↗
PubMed1985

Analysis of major histocompatibility complex haplotypes of t-chromosomes reveals that the majority of diversity is generated by recombination.

t-chromosomes are natural polymorphisms in feral populations of mice that are thought to be descended from a single ancestral chromosome. They carry an inversion of at least 10 cM surrounding the major histocompatibility complex (MHC) that effectively prevents recombination between a t-bearing chromosome and wild type chromosomes. However, on the rare occasion when two different t-chromosomes meet in a wild female, recombination occurs at an apparently normal rate. Since they contain the highly polymorphic MHC, their limited origin and restricted chances for recombination make t-chromosomes a valuable tool for studying the relative contributions of mutation and recombination to the generation of diversity. Using 13 different serological reagents to class I antigens, and studying restriction enzyme polymorphisms detected with three molecular probes for class II genes examined with three endonucleases, we present data indicating that the major factor responsible for the diversity of class I antigens is recombination, but that for class II genes, mutation must play an important role in addition to recombination.

Animals↗
PubMed1985

Definitive chromosomal location of the H-2 complex by in situ hybridization to pachytene chromosomes.

Chromosome 17 of the mouse carries the H-2 complex and the T/t complex. An understanding of the organization of this region and an accurate genetic map of chromosome 17 would be of great value for both immunologists and developmental biologists. Until now the only maps available have been derived solely from recombinational studies using several translocations, an inherently inaccurate method. We have found the definitive location of the H-2 complex by the use of in situ hybridization. Our results show that both the T/t complex and the H-2 complex map to positions far more distal than the generally accepted map positions. This proves that recombination in Robertsonian chromosomes underestimates physical map distances on chromosome 17.

Animals↗
PubMed1985

Contamination and effects in freshwater ditches resulting from an aerial application of cypermethrin.

Cypermethrin (Ripcord) was applied at 25 g ai ha-1 by fixed-wing aircraft to a large field (11.6 ha) of winter wheat bordered on three sides by drainage ditches. About 60% of the nominal application rate was deposited on the crop and about 6% (maximum) was deposited over the water surface. The amount of spray drift deposited upwind declined sharply with increasing distance from the treated field. Downwind, the spray drift was small but occurred over a much greater distance. Very low (0.03 micrograms liter-1 maximum) concentrations of cypermethrin were found in subsurface water samples and these declined rapidly after spraying. Bioassay tests, using a sensitive indicator species, confirmed that only a small amount of cypermethrin contamination had occurred in the ditch adjacent to the downwind perimeter of the field. Frequent sampling of the zooplankton and macroinvertebrate fauna of the ditches indicated that there were no marked biological effects resulting from the cypermethrin application. Only a few air-breathing corixids and the highly susceptible water mites showed minor short-term reductions in abundance after spraying. No effects were observed on either caged or indigenous fish stocks and no significant residues of cypermethrin were found in fish tissues.

Animals↗
PubMed1985

Ultrastructural observations on the effect of azelaic acid on normal human melanocytes and a human melanoma cell line in tissue culture.

Azelaic acid has been shown clinically to have a cytotoxic effect on the abnormally active and malignant human melanocyte, but it has no apparent effect upon normal melanocytes. This difference in reactivity between normal and abnormal cells in vivo is further examined here in vitro. The disodium salt of azelaic acid (C(9)2Na) was added to pure and mixed cultures of normal human melanocytes and to cultured human melanoma cells, at 10(-3) M, 10(-2) M, 5 X 10(-2) M, and 10(-1) M for 1 and 6 h. Control cultures and cultures exposed to the same concentrations of the disodium salt of adipic acid (C(6)2Na) were also examined. No damage to cells of any line was observed with diacids at 10(-3) M or 10(-2) M up to 6 h. At 5 X 10(-2) M some mitochondria of melanoma cells appeared swollen. With C(6)2Na at 10(-1) M for I and 6 h, minimal swelling of mitochondria was observed in some cells of all lines. Pure normal melanocytes and melanocytes of mixed cultures exhibited greater swelling of mitochondria with 10(-1) M C(9)2Na at 1 and 6 h, but the mitochondria of the malignant melanocytes were massively swollen with destruction of cristae. Plasma and nuclear membranes and membranes of rough endoplasmic reticulum were intact, but Golgi membranes exhibited vesiculation. These results provide further evidence that azelaic acid damages the human malignant melanocyte and that one of its targets is the mitochondrion. Damage to normal melanocytes, found here, may be due to the fact that, in culture, they are more active than in intact epidermis.

Cell Line↗
PubMed1984

A preliminary double-blind study of intravenous nitroglycerin in acute myocardial infarction.

A preliminary double-blind, placebo-controlled study of the effects of a 48-h intravenous infusion of nitroglycerin (NG) in 140 patients with acute myocardial infarction has been carried out. The patients were randomised to placebo or active treatment within 12 h of the onset of symptoms. Those patients treated with nitroglycerin showed a significant reduction on both days in systolic blood pressure, haemoglobin concentration, and packed cell volume. There was also a significant reduction in diamorphine usage in the first 24 h. There was a higher incidence (non-significant) of dysrhythmia in the placebo group despite an increased usage of antidysrhythmic therapy. The mortality rate in the placebo group was 13%, and 7.8% in the active treatment group, but this difference was not significant. At the 3-month follow-up, 83% of treated patients as opposed to 60% of placebo group were able to resume normal or near-normal activities. Preliminary findings suggest that intravenous NG may be useful treatment for patients with acute myocardial infarction and a larger-scale trial is warranted.

Adult↗
PubMed1984

Gene mapping within the T/t complex of the mouse. IV: The inverted MHC is intermingled with several t-lethal genes.

Using a combination of classical genetics, serology, and molecular genetics, we have mapped as many as possible of the MHC components in t haplotypes. Results indicate that the whole MHC is included in a simple inversion with the relative positions of its genes being intact. Furthermore, some of the t-lethal mutations map very near to, or are intermingled with, components of the MHC. At the centromeric end the t12 lethal maps between TL and H-2D in the Qa region, and distally the tw5 lethal is inseparable from H-2K.

Alleles↗