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Biomedical subjects

A Harrison

Publications and source records attributed to A Harrison.

At least 199 records · Page 11Linked to original sources
PubMed1985

The presence of glucose increases the lethal effect of alpha-chlorohydrin on ram and boar spermatozoa in vitro.

Ram cauda epididymal spermatozoa were incubated for 10 min at 34 degrees C with or without 1.0 mM-RS-alpha-chlorohydrin before (1) 5 mM-D-glucose or (2) 10 mM-L-lactate plus 1 mM pyruvate or (3) 5 mM-D-glucose plus 10 mM-L-lactate plus 1 mM-pyruvate or (4) no substrate was added. Without alpha-chlorohydrin, the motility, the ATP concentration and the energy charge of the spermatozoa were maintained for 240 min by substrate combinations 1-3 but with no added substrate (4) the motility declined after 60 min. All the values decreased dramatically after 10 min in spermatozoa exposed to alpha-chlorohydrin in substrate conditions 1 and 3 (glucose present) but alpha-chlorohydrin had no significant effect in conditions 2 and 4 (no glucose) except after prolonged incubation. In a dose-response experiment glucose-dependent ATP dissipation began to occur with 0.025 mM-RS-alpha-chlorohydrin. A similar effect was seen in boar spermatozoa exposed to 0.1-5.0 mM-alpha-chlorohydrin and 5 mM-D-glucose. With boar spermatozoa the presence of 10 mM-L-lactate and 1 mM-pyruvate as well as glucose prevented the loss of ATP. We conclude that this concerted action of alpha-chlorohydrin and glucose is probably responsible for the contraceptive action of alpha-chlorohydrin and propose that it may depend on 'futile substrate cycling' in the glycolytic pathway.

Adenosine Triphosphate↗
PubMed1984

Lung function in congenital and idiopathic scoliosis.

The vital capacity (VC) in patients with congenital scoliosis was compared with the VC in idiopathic scoliosis. For any given Cobb angle (a measure of spinal angulation) the loss in VC was approximately 15% greater in congenital scoliosis than in idiopathic scoliosis. The greater impairment of lung function in congenital scoliosis may be due to the associated rib deformity or to an underlying lung anomaly.

Adolescent↗
PubMed1984

Antibody responses to meningococcal polysaccharide vaccine in adults without a spleen.

Asplenic persons are at risk for the development of overwhelming sepsis from certain encapsulated bacteria, including meningococci. Since it is not known if asplenic persons can have antibody responses, this study compared such responses following bivalent groups A and C meningococcal polysaccharide vaccine in 22 asplenic subjects and healthy control subjects. There were no adverse reactions to the vaccine. Antibody responses were measured using a solid-phase radioimmune assay; results were compiled for both seroconversions and changes in mean antibody titers of IgG, IgA, and IgM classes. Subjects who underwent splenectomy for trauma and control subjects with spleens showed a polyclonal antibody response to both vaccine antigens. Those persons who underwent splenectomy for nonlymphoid tumors had nearly as good a response as normal subjects. By contrast, asplenic subjects with lymphoid tumors who had received prior chemotherapy and radiotherapy had poor responses to both antigens. It is concluded that meningococcal vaccine is immunogenic in asplenic persons, with the aforementioned exceptions, and that this vaccine should be routinely administered to such persons.

Adolescent↗
PubMed1984

Preparation of a 211At-IgG conjugate which is stable in vivo.

The short lived (t 1/2 7.2 h) alpha-particle emitting halogen 211At has been attached to an antibody by using an acylation reaction to conjugate para-[211At]astato-benzoic acid with rabbit IgG. The conjugate, which is stable in vivo, contains at least 30% of the initial activity of 211At.

Animals↗
PubMed1984

Determination of absorbed dose to blood, kidneys, testes and thyroid in mice injected with 211At and comparison of testes mass and sperm number in x-irradiated and 211At treated mice.

Male mice were injected with 211At and the total absorbed dose to the whole blood, kidneys, testes and thyroid was determined. Extrapolation to man shows a close agreement with the predictions of the International Commission on Radiological Protection (ICRP) for the absorbed dose to human blood, kidneys and testes, but the absorbed dose to the thyroid is about 200 times greater than the ICRP prediction. Comparison of the reduction in testes mass and in sperm numbers 28 days after mice were injected with 211At, or exposed to x rays, indicates a factor of about four for the greater effectiveness of 211At alpha particles over 250 kVcp x rays for the induction of effects.

Alpha Particles↗
PubMed1984

The role of citrate in determining the activity of calcium ions in human semen.

The concentrations of calcium and citrate in 52 samples of human semen obtained from 10 donors were 11.07 +/- 0.41 (mean +/- SEM) and 27.2 +/- 1.62 mM, respectively, and were strongly correlated (r = + 0.79). The pH of the semen was 7.65 +/- 0.069. All 3 parameters varied significantly between the donors (P less than 0.001 in each case), but the activity of calcium ions measured with a calcium electrode was 0.24 +/- 0.022 mM (n = 45) and did not vary significantly between donors. The expected activity of calcium ions was calculated on the hypothesis that the chelation of calcium by citrate could explain the discrepancy between the concentration and the activity of the ion. The result was 0.57 +/- 0.043 mM (n = 52). It was concluded that chelation by citrate could be the most important factor in determining the low activity of Ca++ in semen.

Calcium↗
PubMed1983

Measurement of the rate of wear of dental composite resins by a 90Sr beta particle transmission gauge.

The wear rate of restorative dental composite resins is an important parameter in the assessment of their in vivo performance. The two more widely used methods of quantifying wear are measuring the dimensional change and measuring the change in the mass of the specimen. The former method is complicated by uneven wear of specimens and presents difficulties with samples of irregular shape, and the latter method involves measurements of changes in mass as small as tens of micrograms with specimens of sizes similar to those encountered clinically. A 90Sr beta particle transmission gauge has been designed and constructed to enable the wear rate of small specimens of dental composite resins to be measured. The 90Sr beta particle transmission gauge enables indirect measurements of changes in mass to be made and overcomes some of the difficulties inherent in the direct measurement of mass and length. Applications of the 90Sr beta particle transmission gauge to the measurement of wear rates are given for restorative dental resins having a range of inorganic filler contents and types. The results show that the 90Sr beta particle transmission gauge is capable of measuring the rate of wear to a degree of precision similar to that of micrometer-derived measurements.

Composite Resins↗
PubMed1983

The activity of glyceraldehyde 3-phosphate dehydrogenase in spermatozoa from different regions of the epididymis in laboratory rodents treated with alpha-chlorohydrin or 6-chloro-deoxyglucose.

The activity of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (mUnits/10(6) spermatozoa: mean +/- s.e.m., N = 12) in spermatozoa from the rat epididymis declined from 22.0 +/- 1.4 in the caput to 14.1 +/- 1.3 in the corpus region but there was no further decrease in the cauda region. In hamsters (N = 4), GAPDH activity in spermatozoa declined from 24.8 +/- 2.2 in the caput to 15.2 +/- 1.2 in the distal cauda epididymidis with the greatest decrease between the corpus and proximal cauda regions. In guinea-pigs (N = 4) GAPDH activity in spermatozoa increased from 11.4 +/- 0.79 in the caput to 18.0 +/- 0.7 in the corpus and cauda regions of the epididymis. The activity of GAPDH in spermatozoa therefore changes during maturation in a species dependent manner. GAPDH in spermatozoa from the distal cauda epididymidis of rats given alpha-chlorohydrin (4, 8 or 25 mg/kg/day by mouth) or 6-chloro-6-deoxyglucose (24 or 96 mg/kg/day by mouth) for 10 days was inhibited by greater than 80% but was only inhibited by 25-45% in spermatozoa from the caput epididymidis. The enzyme was inhibited to an intermediate and dose-dependent extent in spermatozoa from the corpus region. A similar pattern of inhibition was seen in spermatozoa from hamsters given alpha-chlorohydrin (50 or 100 mg/kg/day) for 10 days. alpha-Chlorohydrin (66 mg/kg/day s.c.) for 10 days inhibited GAPDH in spermatozoa from the caput or corpus epididymidis of the guinea-pig by less than 20% but decreased GAPDH activity by almost 90% in the cauda region. In rats the greater effect of alpha-chlorohydrin on spermatozoa from the cauda region of the epididymis occurred even after short periods of treatment or when the passage of spermatozoa through the duct was interrupted by a ligature around the corpus region, indicating that the effect is not simply a reflection of the length of time the spermatozoa have spent in the epididymis. It is concluded that either spermatozoa undergo a maturational change which increases their sensitivity to alpha-chlorohydrin or that alpha-chlorohydrin (or an active metabolite) is concentrated in the lumen of the cauda epididymidis.

Animals↗
PubMed1983

D-[1-14C]mannitol and [U-14C]sucrose as extracellular space markers for human spermatozoa and the uptake of 2-deoxyglucose.

[U-14C]Sucrose and D-[1-14C]mannitol were used to determine the tritiated water space of human spermatozoa to validate these compounds as markers for the extracellular space. Calculations based on 0.03 mM-[U-14C]sucrose gave a negative water space. The water space estimated with 0.03 mM-D[1-14C]mannitol was unstable but a stable result was obtained with 0.3 mM-D-[1-14C]mannitol in incubations up to 2 h. The mean water space was 2.21 +/- 0.106 microliters/10(8) spermatozoa (mean +/- s.e.m. for 6 batches of pooled semen). The water space was decreased or abolished by Triton X-100, cold shock, sonication or hypotonic treatment. The water space responded to changes in the osmolarity of the medium by increasing in dilute media. It is concluded that mannitol is an effective extracellular marker for human spermatozoa if concentrations greater than or equal to 0.3 mM are used. When the kinetics of the uptake of 2-deoxyglucose by the spermatozoa were studied by using mannitol as an extracellular marker, the transport was saturable and was inhibited by cytochalasin B. The Km was 1.6 +/- 0.33 mM and the Vmax was 4.2 +/- 0.52 nmol/10(8) spermatozoa/10 sec (mean +/- s.e.m., n = 4).

Biological Transport↗
PubMed1982

Most patients with active symptomatic duodenal ulcers fail to develop ulcer-type pain in response to gastroduodenal acidification.

The most frequent symptom of duodenal ulcer is epigastric pain. However, the pathogenesis of duodenal ulcer pain is not established, although it is often attributed to duodenal acidification. The purpose of this study was to determine whether or not gastroduodenal acidification with either 400 ml of pH 1 citric acid or pH 0.85 hydrochloric acid resulted in ulcer-type pain in patients with endoscopically documented active symptomatic duodenal ulcer under doubled-blind randomized conditions. Thirteen consecutive male duodenal ulcer patients with daytime and nocturnal epigastric pain were studied before beginning medical therapy; five with citric acid or sodium citrate at pH's 1, 3, and 7, and eight with hydrochloric acid at pH 0.85 and pH 7 sodium citrate. Ten normal subjects served as controls. Four of the five symptomatic duodenal ulcer patients failed to have pain with the pH 1 citric acid, while one developed pain. Five of the eight patients tested with 0.15 mM hydrochloric acid had no pain. Of the three who developed pain with hydrochloric acid, two had endoscopic evidence of esophagitis (one developed retrosternal pain and one both retrosternal and epigastric pain), and one had the sensation of epigastric "fullness" with both the pH 0.85 and pH 7 solutions. There were no significant differences (p greater than 0.1) between the responses of the duodenal ulcer and normal subjects nor within the duodenal ulcer group in response to the pH 0.85 or 1.0 solutions versus the pH 7 solution. In summary, gastric acidification equivalent to 80 mmol/hour failed to induce pain in most patients with active symptomatic duodenal ulcer. These observations suggest that duodenal ulcer pain is largely unrelated to duodenal acidification.

Adult↗