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Biomedical subjects

M Gibson

Publications and source records attributed to M Gibson.

At least 127 records · Page 7Linked to original sources
PubMed1990

The 24-hour pattern of the levels of serum progesterone and immunoreactive human chorionic gonadotropin in normal early pregnancy.

The purpose of this study was to characterize the levels of progesterone and hCG and the variability of those levels over 24 h in early pregnancy. Venous blood sampling was performed every 30 min during the first trimester of a subsequently normal pregnancy in 19 women. The variability in each progesterone and hCG data series was evaluated by three methods: 1) comparing the coefficient of variation (CV) of each individual hormone data set to the respective assay CV, 2) examining each data set for pulses, and 3) relating changes in hormone levels to the ingestion of a meal. The CV for each individual progesterone data set was greater than the assay CV (CV progesterone, 3.7%) in all subjects (range, 5.58-21.90%). The CV for each individual hCG data set was greater than the assay CV for hCG (CV hCG, 4.3%) in 17 of 19 subjects (range, 3.27-10.95%). Mean (+/- SE) progesterone and hCG peak frequencies were 2.4 +/- 0.3 and 1.7 +/- 0.3/24 h, respectively. When postprandial levels of progesterone were normalized to a percentage of preprandial levels, there were maximum decreases in mean progesterone levels of 15.4 +/- 2.6% and 13.1 +/- 1.9% 1 h after initiation of the lunch and dinner meals, respectively (P less than 0.05). Postprandial hCG levels decreased by 2.3 +/- 1.9% and 0.4 +/- 1.6% during this same time period (P greater than 0.05). These findings suggest that 1) both progesterone and hCG levels fluctuate during a 24-h period in early pregnancy; 2) this variability of both hormones is greater than inherent assay variability and can be resolved into a short term pattern of pulses, suggesting alterations in episodic secretion, metabolic clearance, or volume of distribution of the hormone; and 3) a portion of the variability in the progesterone time set may be due to the ingestion of meals.

Adult↗
PubMed1990

A CD5+ B cell hybridoma derived factor(s), which induces maturation of CD5+, idiotype-specific B-cell populations.

A number of investigators have demonstrated the association of CD5+ (Ly-1/Leu-1) B cells with autoimmunity, excessive B-cell proliferation, and transformation. Previous work from our laboratory, among others, suggests that the selective advantage of this frequently autoreactive B-cell subset is to provide activation signals to conventional antigen-specific B cells. If one current hypothesis is correct then the overrepresentation of CD5+ B cells in some diseases and their novel capacity to act as helper cells reflect the activities of a separate B-cell lineage. Because of these observations it is of particular interest to evaluate the factors which contribute to the maturation of the CD5+ B-cell subset. The possibility that CD5+ B cells produce a factor or factors capable of influencing their own development was the focus of the present investigation. Rather than attempt to obtain soluble factors from heterogeneous CD5+ B-cell populations which could be contaminated with cytokine secreting monocytes or which could require as yet undefined activation signals in order to secrete putative factors, we chose to evaluate the production of CD5+ B-cell inducing factor(s) by monoclonal CD5+ B-cell hybridomas. Added incentive to this approach was provided by the observation that these hybridomas elaborate a factor(s) which, together with (NPb) idiotype-specific antibody produced by the hybridoma, substitutes for CD5+ B-cell populations in activating antigen-specific (NPb idiotypic) B cells in vitro. Furthermore, because of the low percentage of CD5+ B cells in the spleen and their relatively low level of CD5 antigen expression, we employed a sensitive functional assay rather than surface antigen expression alone to detect small numbers of mature CD5+ B helper cells. With this previously described system it was possible to observe the induction of functional CD5+ B cells following a 40 h culture of apparently CD5- B-cell populations with a 19-22 kd factor or factors derived from a CD5+ B hybridoma. Data presented here and elsewhere suggest that this CD5+ B-cell inducing activity is not mediated by IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IFN-gamma, GM-CSF, or TNF. The role that such a B cell derived, B-cell directed factor may play in immunity and disease is discussed.

Animals↗
PubMed1990

Outpatient carpal tunnel decompression without tourniquet: a simple local anaesthetic technique.

Carpal tunnel release was performed under local anaesthesia in 108 wrists of 98 patients. The local anaesthetic (bupivacaine 0.5% and adrenaline) was injected into the subcutaneous tissue down to the flexor retinaculum in the line of the incision. The median nerve was not anaesthetised. No tourniquet was required and analgesia was complete in all but four patients, who complained of some minor discomfort on cutting the flexor retinaculum. Protracted postoperative analgesia was obtained.

Adult↗
PubMed1990

A randomized, controlled trial of clomiphene citrate and intrauterine insemination in couples with unexplained infertility or surgically corrected endometriosis.

This study was initiated to test the hypothesis that treatment with clomiphene citrate (CC) and intrauterine insemination (IUI) results in increased fecundity when compared with periovulatory intercourse in couples with either unexplained infertility or surgically corrected endometriosis. Sixty-seven couples entered a randomized, prospective trial comparing CC/IUI with observation. During the study, there were 14 pregnancies in 148 treated cycles (fecundity = 0.095) compared with 5 pregnancies in 150 untreated cycles (fecundity = 0.033). Using life-table analysis and the log-rank test, the difference in fecundities was statistically significant. Pregnancy outcome was not significantly different between the two groups. When comparing conception with nonconception cycles during treatment, no differences between the size of the lead follicle or the number of dominant follicles was detected. We conclude that treatment with CC/IUI improves fecundity in couples with unexplained infertility or surgically corrected endometriosis.

Clomiphene↗
PubMed1990

Serum concentration of CA-125 during the first trimester of normal and abnormal pregnancies.

A prospective study was initiated to closely examine maternal serum concentrations of CA-125 during the early first trimester of normal and abnormal pregnancies. Sequential serum specimens were obtained from 43 women with a normal intrauterine pregnancy, 20 with a surgically confirmed ectopic gestation and 10 whose pregnancies ended in spontaneous abortion. In normal pregnancies the CA-125 levels increased significantly from the first week after the missed menses (39.9 +/- 8.2 U/mL [mean +/- SEM]) to the second week (48.3 +/- 6.9 U/mL) (P less than .05) and from the second to the third week (62.5 +/- 9.8) (P less than .05). After the third week after the missed menses the mean CA-125 serum concentrations plateaued, but levels observed during the fourth (59.6 +/- 8.8 U/mL) and fifth (48.8 +/- 7.2 U/mL) weeks were still significantly greater than at week 1. In addition, the mean CA-125 concentrations were significantly higher in normal pregnancies than in ectopic gestations during the second, third and fourth weeks after the missed menses. Although there was a tendency for the CA-125 levels to be lower in women who had a spontaneous abortion when compared to normals, these differences were not statistically significant. Serum levels of CA-125 may prove useful in monitoring early pregnancy.

Abortion, Spontaneous↗
PubMed1989

Observation of production of immunoactive prolactin by normal human connective tissue in cell culture.

Data from our in vitro studies indicate a new source of prolactin (PRL)-like activity, normal human connective tissue. Fascial cells from primary culture and subsequent passages produced an extracellular antigen which specifically reacted in a radioimmunoassay RIA developed to detect human pituitary PRL. An initial peak or first surge of fascial PRL-like activity occurred between 4 and 15 d in primary culture. Ibuprofen, cytotoxic levels of 0.01% azide, or 7.5 mM EDTA and medium lacking serum [fetal bovine serum (FBS)] significantly (P less than or equal to 0.05) reduced PRL-like activity levels, whereas female steroids, 257 to 342 milliosmolarity, 1 to 3.6 mg/ml glucose, 2 to 20% FBS, and dialyzed FBS (MWCO approximately 1 kDa) were without effect. Optimum production of PRL-like activity occurred at pH 7.3. A second surge began after 18 d and continued until passage indicating that perhaps two populations of cells produced PRL-like activity in primary culture. Production of PRL-like activity by cells from early passages (1 and 2) became detectable at confluence, was serum-dependent, showed two patterns (tonic, rising to plateau), and averaged 3.2 fg.cell-1.3 d-1 feed interval. Cells from late passages showed morphologic damage from repetitive trypsinization, aging, and reduced production of PRL-like activity with aberrant production pattern. Production of PRL-like activity was maintained in an unusual long-term culture. These in vitro studies demonstrate the most recently recognized and ubiquitous source of human extrapituitary PRL or PRL-like activity, normal connective tissue (fascia).

Abdominal Muscles↗
PubMed1989

Absence of progestational activity of oral spironolactone.

Menstrual irregularity is a recognized side effect of spironolactone when used as a treatment for hirsutism in women. This effect has been attributed to the progestational activity of spironolactone observed in animal models. However, when oral spironolactone was given to women with appropriately estrogen-primed endometrium, secretory transformation of the endometrium was absent in comparison with control cycles. When control cycles were repeated with the addition of spironolactone, a decidualized endometrial response was seen. These findings suggest that spironolactone at clinically used dosages does not act as a progestin or an antiprogestin on the human endometrium.

Endometrium↗
PubMed1989

Problems with curriculum implementation in in-service clinical education.

We report a hitherto poorly documented cause of failure of curriculum implementation. The case of the clinical training of foreign medical graduates (externs) in Hong Kong is used to illustrate problems that may arise in professional education where in-service work in institutions is part of the educational process. The example is particularly relevant to health professional education which generally involves a significant in-service component. We used participant observation, questionnaires and brief interviews to obtain data from 97 externs and 48 supervisors. The results indicated that between a third and a half of the externs did not receive experiences as designated in the curriculum. Apart from age, individual characteristics of the externs did not show statistically significant relationships to the kind of experience obtained. The major significant variable (P less than 0.01) was the type of hospital where the exposure was gained. In one type of hospital the externs shared the work-load, whilst in the other type they were largely used as observers with minor technical duties. The supervisors' perception of the externs' professional capabilities varied according to the hospital. We believe that the failure of curriculum implementation was related to conflict between institutional needs, which must be safeguarded by the supervisors, and the educational needs of the learners. This conflict affects the perceptions of the supervisors and without their full cooperation the curriculum cannot be delivered. The roles and perceptions of supervisor and learner must overlap sufficiently for the system to be effective and this must be taken into account by curriculum planners.

Attitude of Health Personnel↗
PubMed1989

Severe segmental narrowing of the spinal cord: an unusual finding in congenital spastic paraparesis.

A three-year-old boy is reported who had congenital spastic paraparesis caused by severe segmental narrowing of the spinal cord. X-rays of the spine showed thoracolumbar scoliosis and anomalies of the thoracic vertebrae from T5 to T11. Myelography, with CT scanning, demonstrated severe narrowing of the T5 to T12 segments of the spinal cord, measuring only 1.5 mm at T10. This is believed to be the first report of this unusual anatomical finding in congenital spastic paraparesis. An early embryonic vascular insult is thought to be the most likely cause.

Child, Preschool↗
PubMed1989

The effect of a meal on circulating steady-state progesterone levels.

Five fasting women had a steady-state concentration of progesterone (P) established by a constant intravenous infusion of P during the early proliferative phase of a spontaneous menstrual cycle. Alterations in the levels of P after the ingestion of a balanced liquid meal were sought. Eight studies were performed utilizing the five women. P levels decreased in all observations; the mean (+/- SE) decrease was 34.2 +/- 0.2% 60 minutes after the meal (p = 0.0001). By contrast, mean cortisol (F) levels increased 29.5 +/- 14.4% (p = 0.11) 60 minutes after the meal and postprandial F levels were variable both within and between individuals. The correlation between the change in P and F, 60 minutes after the meal, was not significant (r2 = 0.015, p = 0.77). These findings indicate that: 1) The postprandial state is associated with a transient and large increase in the metabolic clearance rate of P and/or a change in the volume of distribution of P and 2) Increased F levels after meals alone do not appear to account for a postprandial decrease in P.

Adult↗
PubMed1989

Prostaglandin F2 alpha synthesis and metabolism by luteal phase endometrium in vitro.

Differences in prostaglandin (PG) F2 alpha synthesis and degradation were sought between early luteal endometrium (histology day 15 to 22, n = 6) and late luteal endometrium (histology day 23 to 28, n = 6). In addition, alterations in PGF2 alpha synthesis and degradation in response to 17 beta-estradiol (E2) and progesterone (P) were examined to clarify the mechanism of steroid modulation of endometrial PG production (n = 12). Endometrium was maintained in tissue culture and the concentration of PGF2 alpha and 13,14 dehydro-15 keto F2 alpha (DHKF2 alpha) was determined in spent media by radioimmunoassay. Prostaglandin F2 alpha and DHKF2 alpha output from luteal endometrium exposed to P and E2 + P were both significantly reduced when compared with no addition or E2 treatments. This implies that the modulation of PGF2 alpha output by P in vitro is secondary to altered synthesis. There was an increase in PGF2 alpha output from late luteal endometrium when compared with early luteal endometrium in the P and E2 + P treatments, but DHKF2 alpha remained unchanged. These data imply that the temporal increase in PGF2 alpha output is the result of alterations in both PG synthesis and catabolism.

Culture Techniques↗
PubMed1988

Physicochemical characterization and functional activity of fibroid prolactin produced in cell culture.

Evidence from our laboratory with the use of cultured (primary and passaged) cells has extended our initial observation that human uterine fibroid is an extrapituitary source of prolactin. Fibroid prolactin antigen in conditioned medium reacted specifically in radioimmunoassay for human pituitary prolactin. Control experiments demonstrated that the radioimmunoassay results were not spurious due to degradation of tracer 125I-labeled prolactin. Immunoparallel dilution curves indicated antigenic relatedness of pituitary and fibroid prolactin. In a calibrated Sephadex G-100 column, fibroid prolactin eluted in the same region (20.3 to 20.9 kd) as purified pituitary prolactin. Glycosylated prolactin, detected by concanavalin A affinity column chromatography, appeared to constitute only a small percentage of fibroid prolactin made in culture. The ratio of fibroid prolactin bioactivity (lactogen Nb2 lymphoma bioassay) to antigen (radioimmunoassay) was 0.77. These data indicate that human uterine fibroid tissue produces a molecule similar to or, perhaps, identical with pituitary prolactin.

Cells, Cultured↗
PubMed1988

Photoperiodic disruption of photorefractoriness in the ewe.

The primary objective of this study was to determine the duration of exposure to a long-day or short-day photoperiod required to disrupt photorefractoriness to short-day and long-day photoperiods, respectively. In Experiment 1, 4 groups of Suffolk breed ewes--designated B1, B2, B3, and B4--were placed in photochambers one day before the winter solstice, exposed to a 16L:8D photoperiod for 0, 30, 60, or 90 days, and then exposed to a 10L:14D photoperiod until the time of the summer solstice. Blood samples taken by venipuncture thrice weekly were analyzed for progesterone concentrations. The interval between start of the study and cessation of estrous cycles did not differ significantly between groups (p greater than 0.05). All 6 ewes in Group B1 then remained in anestrus for the duration of the study. Four of the 6 ewes in Group B2, and all ewes in Groups B3 and B4 resumed cycles after exposure to the 10L:14D photoperiod. In Experiment 2, 4 groups of ewes--designated A1, A2, A3, and A4--were placed in photochambers one day before the summer solstice, exposed to a 10L:14D photoperiod for 0, 30, 60, and 90 days, respectively, and then exposed to a 16L:8D photoperiod. Ewes in Group A1 started estrous cycles at a time not significantly different from ewes kept outdoors. However, onset of cycles was significantly advanced (p less than 0.05) in ewes exposed to 10L:14D. After ewes were returned to the 16L:8D photoperiod, estrous cycles were suppressed in 5 of 6 ewes in Group A2 and in all ewes in Groups A3 and A4.(ABSTRACT TRUNCATED AT 250 WORDS)

Anestrus↗