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Biomedical subjects

J J Morrison

Publications and source records attributed to J J Morrison.

At least 55 records · Page 3Linked to original sources
PubMed1994

Tissue collagenase: serum levels during pregnancy and parturition.

Serum levels of tissue collagenase, matrix metalloproteinase-1, were measured in both longitudinal and cross-sectional studies, in 332 pregnant women and 27 non-pregnant volunteers. The enzyme-linked immunosorbent assay (ELISA) used is the first described to measure collagenase in serum directly, is specific, and is rapid and reproducible. Levels were determined throughout pregnancy, during term and preterm labour, and in the post-partum period. Serum tissue collagenase levels were elevated in pregnancy (P < 0.001). There was no difference between levels of serum collagenase prior to labour at term and those observed during labour. Similarly, there was no significant difference in levels obtained during preterm labour and those at a similar gestation in women who subsequently delivered at term. No significant decrease in levels had occurred by the 4th post-partum day. In view of these findings of unaltered matrix metalloproteinase-1 levels in association with labour, previous reports of raised serum collagenase activity in association with the onset of spontaneous labour, at term and preterm gestation periods, may be due to increased neutrophil collagenase activity.

Collagenases↗
PubMed1994

Tissue inhibitor of metalloproteinases: serum levels during pregnancy and labor, term and preterm.

OBJECTIVE: To determine the levels in serum of tissue inhibitor of metalloproteinases (TIMP) in pregnancy and to examine the possibility of a time course in relation to parturition, both term and preterm. METHODS: Serum tissue inhibitor of metalloproteinases was measured using an enzyme-linked immunosorbent assay. A cross-sectional study was conducted in 333 women during pregnancy, labor, and the postpartum period and in 27 nonpregnant volunteers. Longitudinal data were obtained from 22 women who provided a sample at term, during labor, and in the postpartum period. RESULTS: In uncomplicated pregnancies, serum TIMP levels were low from the onset of pregnancy until 37 weeks' gestation, in comparison to levels in nonpregnant women (P < .001). During the final weeks of pregnancy, levels rose and at 37-42 weeks were similar to nonpregnant levels. The levels did not change with the onset of labor. Serum concentrations of TIMP obtained during preterm labor were elevated compared to a control group of patients at a similar gestation who subsequently delivered at term (P < .01). Serum TIMP levels were significantly higher during the postpartum period than at all other times (P < .001). CONCLUSIONS: Changes in serum TIMP levels during and after pregnancy may parallel the remodeling of the extracellular matrix that takes place throughout this period. Further work is necessary to evaluate the prognostic value of TIMP for preterm labor.

Cross-Sectional Studies↗
PubMed1993

Alternatively spliced mRNAs for human endothelin-2 and their tissue distribution.

The cDNA for Endothelin-2 (ET-2) has been previously cloned and characterised; however, ET-2 remains the least studied of the endothelin isopeptides and little is known of its function and location. In the present study reverse transcriptase-polymerase chain reaction revealed the presence of seven alternatively spliced mRNA variants encoding ET-2, with a specific pattern of distribution in various human tissues. Computer alignment and analysis of the DNA sequences demonstrated alternative splicing of five exons of 52, 169, 123, 99 and 174 base pairs, in the carboxy terminal region of the mRNA encoding preproET-2. This region contains sites for the post-transcriptional processing of preproET-2 into mature ET-2, therefore we postulate that post-transcriptional processing may be disrupted or altered in these variants.

Alternative Splicing↗
PubMed1993

Properties of large-conductance K+ channels in human myometrium during pregnancy and labour.

The conversion of the electrically silent pregnant uterus to highly excitable at term represents a dramatic physiological event which is poorly understood. Here we provide the first description, from single-channel recordings, of a large conductance (212 pS) calcium-activated potassium channel (BKCa) in human pregnant myometrium which, in labour tissue, is either absent or has been considerably altered in its physiological and pharmacological properties. In the latter, the K+ channels have an identical conductance (221 pS) and K+ selectivity to BKCa channels but exhibit no Ca2+ or voltage sensitivity. We have termed these BK channels. Furthermore, the activity of the BKCa channel from pregnant tissue is inhibited by internal application of Ba2+ but not tetraethylammonium (TEA), whereas the activity of the BK channel is sensitive to internal TEA but not Ba2+. The role of the BKCa channel may be to suppress myometrial activity during gestation whereas BK channel activity may be important in providing a Ca(2+)-independent K+ conductance which would allow cytoplasmic Ca2+ levels to rise without activating a counteracting Ca(2+)-dependent outward current, normally provided by the BKCa channels which, by its very nature, would tend to oppose depolarization. The findings suggest that K+ channels may have an important role in determining the functional activity of the myometrium.

Adenosine Triphosphate↗
PubMed1993

The effects of potassium channel openers on isolated pregnant human myometrium before and after the onset of labor: potential for tocolysis.

OBJECTIVE: Our purpose was to investigate the effects and pharmacologic properties of potassium channel openers in isolated pregnant human myometrium. STUDY DESIGN: Biopsy specimens of myometrium obtained from 67 women during pregnancy and labor were used for isometric recording under physiologic conditions. RESULTS: Levcromakalim and pinacidil, two prototype potassium channel openers, are potent inhibitors of spontaneous and induced (0.5 nmol/L oxytocin and 10 mumol/L phenylephrine) contractions in isolated human pregnant myometrium, obtained before and after the onset of labor. The sulfonylurea glibenclamide is an apparent competitive antagonist of this inhibition. No antagonism was observed with the sulfonylurea tolbutamide. Both potassium channel openers significantly inhibited contractility evoked by low (10 and 20 mmol/L) but not high (40 and 80 mmol/L) concentrations of extracellular potassium chloride. CONCLUSION: These findings suggest that the relaxant ability of levcromakalim and pinacidil in human pregnant myometrium is because of potassium channel activation. This introduces a potential new approach for tocolysis.

Benzopyrans↗
PubMed1992

Instrumental rotational delivery in primiparae.

We analysed 98 consecutive instrumental rotational deliveries of babies weighing > 2,500 grams in primiparae. Our aim was to compare the use of Kjelland's forceps with vacuum delivery with regard to efficacy and safety. The vaginal delivery rate was similar with Kjelland's forceps (96%) and vacuum (90%). The vacuum cup failed to effect rotation in 14% and 77% required forceps delivery after vacuum rotation. The vacuum took longer to effect delivery (P < 0.01). Women delivered with Kjelland's forceps had higher pain scores in the puerperium. There were no perinatal deaths. Low Apgar scores and cord arterial pH values of less than 7.20 were recorded more frequently after vacuum rotation (p < 0.05). Babies delivered with Kjelland's forceps sustained more physical trauma. The incidence of asphyxial encephalopathy was the same in both groups. We would recommend a more selective approach to the use of both rotational vacuum and Kjelland's forceps in primiparae.

Adult↗
PubMed1991

Prevalence of premenstrual syndrome in Pakistani women.

The prevalence of premenstrual syndrome (PMS) was determined in 1600 women belonging to various socioeconomic groups in Karachi. Of the total, 33% had PMS, whose prevalence was high in lower socioeconomic group living in socially deprived areas. A direct association of PMS was noted with parity, being low in low parity group. Major complaints were pain in lower abdomen, cramps and backache with majority taking no treatment for their complaints.

Data Collection↗
PubMed1988

Analysis of the responding and stimulating cells in the AMLR of patients with rheumatoid arthritis using limiting dilution.

Plastic adherent and non-adherent mononuclear cells derived from synovial fluid were found to stimulate peripheral blood mononuclear cells of patients with rheumatoid arthritis (RA) in an autologous mixed lymphocyte reaction (AMLR). Stimulation produced by adherent cells was consistently greater than that produced by non-adherent mononuclear cells. CD11 enriched cells were not significant stimulators in the AMLR, however their presence was required for a significant reaction to occur. Limiting dilution studies revealed that the most plausible model involved two or more cells of the same type in each of the stimulator and responder populations for the AMLR to occur.

Arthritis, Rheumatoid↗
PubMed1987

Plasma volume changes and cardiovascular responses associated with weight lifting.

Ten experienced weight lifters were studied to determine the influence of strenuous, free-weight, squat lift exercise on changes in plasma volume, mean arterial pressure, and the rate pressure product. After a 40-min postural adjustment prior to upright exercise, each subject completed eight sets of eight repetitions of the squat exercise at 55% of the one-repetition maximum. Electrocardiogram heart rate was monitored throughout the test, and blood pressure was determined at the completion of each exercise set. Arterialized capillary blood was drawn during sitting and standing pre-exercise and at the end of the second, fourth, sixth, and eighth sets for the measurement of hemoglobin, hematocrit, and plasma protein concentration, and after the last set for blood lactate. Five additional subjects participated in a postural control comparison. The results of the ANOVA showed a significant loss in plasma volume over the trials which was 2 1/2 times greater than for the control subjects (17.9 vs 7.7% loss) over the same period of time. Exercise rate pressure product increased by 2.85 times resting while only 1.1 times resting for the control subjects. An elevation in mean arterial pressure was found to be correlated to changes in plasma volume, r = -0.98. This study found that plasma volume is reduced while the rate pressure product is increased during the squat lift exercise.

Adult↗
PubMed1984

Venom of the Australian rough-scaled snake, Tropidechis carinatus: lethal potency and electrophysiological actions.

A series of experiments to define the lethal potency (LD50) and electrophysiological properties of the venom of the Australian Rough-scaled Snake (Tropidechis carinatus) are described. Crude pooled venom contains at least five fractions which were separated using liquid chromatography and high pressure liquid chromatography techniques (Fractions I-V). LD50 studies are reported using each of these fractions, with data for both adult and neonatal mice. Fraction I (mol. wt greater than 100,000) was essentially non-toxic. Fraction IV (mol. wt less than or equal to 10,000) and Fraction V (mol. wt less than 1,000) were potent toxic components with LD50'S (s.c. injection; fraction in 0.1% bovine serum albumin and 0.85% saline; neonatal mice) of 0.04 mg/kg and 0.06 mg/kg respectively. LD50'S for the whole crude venom were similar in both adult and neonatal mice. Electrophysiological studies using a Bulbring preparation (rat isolated phrenic nerve-hemidiaphragm) indicated that Fractions I, IIa and IIb were inactive. Fraction IV (mol. wt less than or equal to 10,000) caused rapid neuromuscular blockade which appeared to be irreversible. Neurophysiological experiments with a rat isolated extensor digitorum longus muscle preparation suggested that the major toxic activity of the whole venom resides in Fractions III and IV, and that both of these fractions have presynaptic and postsynaptic action.

Animals↗
PubMed1983

Can Australians identify snakes?

A study of the ability of Australians to identify snakes was undertaken, in which 558 volunteers (primary and secondary schoolchildren, doctors and university science and medical students) took part. Over all, subjects correctly identified an average of 19% of snakes; 28% of subjects could identify a taipan, 59% could identify a death adder, 18% a tiger snake, 23% an eastern (or common) brown snake, and 0.5% a rough-scaled snake. Eighty-six per cent of subjects who grew up in rural areas could identify a death adder; only 4% of those who grew up in an Australian capital city could identify a nonvenomous python. Male subjects identified snakes more accurately than did female subjects. Doctors and medical students correctly identified an average of 25% of snakes. The ability to identify medically significant Australian snakes was classified according to the observer's background, education, sex, and according to the individual snake species. Australians need to be better educated about snakes indigenous to this country.

Adolescent↗
PubMed1983

Further studies on the mass of venom injected by Elapid snakes.

Further experimental studies to determine the mass of venom injected by medically-significant Australian elapids are reported. The use of a modified enzyme immunoassay technique to measure venom injected during snake bite is presented. The feeding biting pattern of the Australian eastern brown snake (Pseudonaja textilis) is described. Using data from ten different snakes of this species, it is established that the mass of venom delivered in a first-bite is 4.69 +/- 0.85 mg (mean +/- S.E.) and a mean of 91% of the delivered venom is injected s.c. or into deeper tissues in a first-bite. For this species, the mass of venom delivered sequentially in a bite sequence falls to 1.32 +/- 0.94 mg in the third bite in such a sequence. For the Australian rough-scaled snake (Tropidechis carinatus), the mass of venom delivered in a first feeding bite is 6.15 +/- 2.23 mg, falling to a minimum of 1.92 +/- 0.61 mg in the third bite of a sequence. for the Australian death adder (Acanthophis antarcticus) the mass of venom delivered in a feeding bite is 41.95 +/- 16.13 mg for a first bite. Biting data is also presented for three species of the genus Pseudechis (the Australian mulga (king brown) and black snakes.

Animals↗