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Biomedical subjects

M De Silva

Publications and source records attributed to M De Silva.

At least 37 records · Page 2Linked to original sources
PubMed1988

Hypothalamic-pituitary function in chronically cystic and regularly cycling dairy cows.

Studies were conducted to characterize, in detail, serum luteinizing hormone (LH) profiles 1) before and at various times after ovariectomy (OVX) in chronically cystic (CC) and regularly cycling (control) cows and 2) after injection of luteinizing hormone-releasing hormone (LHRH) and estradiol-17 beta (E2) to OVX CC and control cows. Blood samples were drawn from follicular-phase control cows and CC cows (pre-OVX) for 8 h at 15-min intervals. Cows were bilaterally OVX, and blood samples were collected for 8 h at 15-min intervals at 1, 2, and 4 wk after OVX. Five weeks after OVX, cows were challenged with 20 micrograms LHRH i.m. Six weeks after OVX, cows were challenged with 1 mg E2 i.m. Pulse frequency, pulse amplitude, and interpulse interval were not different (p less than 0.05) before or after OVX in CC and control cows. Peak LH, time to the peak, and area under the curves were not different (p greater than 0.05) after LHRH administration in CC and control cows. After injection of E2, peak LH levels were higher (p less than 0.05) in CC cows than in control cows. However, the time to the peak or the area under the curves were not different (p greater than 0.05) between groups. It appears that the feedback regulation of the hypothalamic-pituitary axis to circulating estrogen levels is altered as a result of the cystic condition.

Animals↗
PubMed1987

Production of an ovine monoclonal antibody to testosterone by an interspecies fusion.

Hybridomas were made between NS1/1-Ag4-1 mouse myeloma cells and peripheral blood lymphocytes from a sheep immunized with a testosterone-protein conjugate. ELISAs were developed to detect ovine IgG and specific ovine anti-testosterone and these were used to screen the colonies. Although the cells fused acceptably only 3% of colonies secreted detectable quantities of antibody. The antibody was secreted at low levels (2.5 ng/ml) but was of high affinity (KD = 7.63 x 10(-12) M/1). One line, O/M 4.22, continued to secrete in culture for four months until the termination of the experiment.

Animals↗
PubMed1986

Ovarian response to active immunization against luteinizing hormone in the cow.

Two experiments were conducted to determine whether active immunization against luteinizing hormone (LH) could lead to ovarian cyst development in the cow. In Experiment 1, cyclic beef heifers were randomly assigned to receive bovine LH (bLH) conjugated with ovalbumin (LH-immunized; n=4) or ovalbumin alone (control; n=5). Blood samples were collected at monthly intervals from the LH-immunized heifers to determine antibody titers. Heifers were observed for estrous behavior twice daily. All heifers were slaughtered 4 mo after initial immunization and ovaries examined for follicular status. In Experiment 2, mature dairy cows were immunized with bLH (LH-immunized; n=4) or ovalbumin alone (control; n=3). Weekly blood samples were collected from all cows for 26 wk and ovaries were rectally palpated. Sera from all of the LH-immunized heifers and cows had antibodies to LH. All of the LH-immunized animals stopped cycling 1 mo after immunization. In spite of the fact that serum follicle stimulating hormone levels were unaffected, ovarian cysts could not be found in either the LH-immunized heifers or cows.

Journal Article↗
PubMed1986

The costoclavicular syndrome: a 'new cause'.

Costoclavicular compression in obese, heavy breasted, middle aged or elderly women from tight, narrow brassiere straps is a common cause of neck, shoulder, and arm pain. Clues to diagnosis and simple treatment measures, including the use of a shoulder pad, are described.

Aged↗
PubMed1986

Azathioprine in giant cell arteritis/polymyalgia rheumatica: a double-blind study.

The ability of azathioprine to reduce the maintenance prednisolone requirement of 31 patients with polymyalgia rheumatica (PMR) or giant cell arteritis (GCA), or both, was tested in a double-blind placebo controlled study over one year. Clinical and laboratory assessments were made at four-weekly intervals over a period of 52 weeks. A statistically significant difference (p less than 0.05) in mean prednisolone dose was noted between the two groups at the end of 52 weeks, there being a fall in steroid requirement in the azathioprine treated group.

Aged↗
PubMed1986

Follicular development after administration of adrenocorticotropin to nonlactating Holstein cows.

The effect of chronic administration of adrenocorticotropin on ovarian follicular development was studied. Twelve nonlactating Holstein cows received either 100 IU adrenocorticotropin (n = 6) or saline (n = 6) at 12-h intervals, commencing d 16 and continuing until d 23 of an induced estrous cycle (estrus = d 0). Cows were slaughtered on d 24, ovaries collected, and number of visible antral follicles recorded. Estradiol-17 beta, androstenedione, and testosterone in follicular fluid, and luteinizing hormone and follicle-stimulating hormone receptors in follicular tissue of the largest follicles were determined. Largest follicles were classified as ovulatory or nonovulatory based on the estrogen to androgen ratio. One cow treated with adrenocorticotropin, but none treated with saline, had ovulated by slaughter. The numbers of small, medium, and large antral follicles were 0, 1, and 5 for cows treated with adrenocorticotropin and 0, 1, and 6 for cows treated with saline. Follicular diameter (15.0 +/- 1.0 versus 14.0 +/- 2.0 mm) and follicular fluid volume (2.9 +/- .8 versus 2.2 +/- .5 ml) of the largest follicle in cows treated with adrenocorticotropin or saline were not different. No differences were found in the number of luteinizing hormone and follicle stimulating hormone receptors nor in the proportion of ovulatory versus nonovulatory follicles between treatments. We conclude that adrenocorticotropin administered at 100 IU every 12 h during the follicular phase does not significantly alter follicular development in the nonlactating dairy cow.

Adrenocorticotropic Hormone↗
PubMed1985

Pooled cells versus individual screening cells in pre-transfusion testing.

Pooling of screening red cells used in pre-transfusion testing has been discouraged by many workers since it might lead to the failure to detect alloantibodies. However, there is minimal scientific data to support this view and in the UK a high proportion of blood transfusion laboratories were still using pooled red blood cells for antibody screening in 1982-1983. In order to solve the dilemma of sensitivity of serological tests when using pooled versus individual screening cells, a comparative evaluation of both approaches was carried out. One hundred and five sera known to contain weak, warm-reacting clinically significant alloantibodies were tested by the three same standard sensitive techniques using samples of individual screening cells and a pool of the same cells in parallel. Our results show that when pooled cells were used, 12% of the selected alloantibodies were undetectable and a further 23% were only detectable microscopically. All antibodies examined were easily detectable macroscopically when individual screening cells were used. It is concluded that the sensitivity of pre-transfusion screening tests is reduced when pooled red cells are employed as opposed to individual samples of screening cells and that the use of pooled cells should be discouraged in routine pre-transfusion and antenatal antibody screening.

Blood Transfusion↗
PubMed1985

Indomethacin inhibition of ovulation in the cow.

Indomethacin or saline was administered via intramuscular, intrauterine or intraovarian routes to dairy cows, within 24 h after standing oestrus was first observed. The incidence of ovulation was determined at slaughter. All of the saline-treated cows (18/18) ovulated. Ovulation was not blocked after intramuscular injection (0/6) or intrauterine infusion (0/6) of indomethacin. In all cows, ovulation was blocked after intraovarian injection (6/6) of indomethacin. These findings add support to the hypothesis that prostaglandins play an essential role in ovulation in the cow as in many other mammalian species.

Animals↗
PubMed1984

Estrous response and pregnancy rates following calf removal in beef cows treated with prostaglandin F(2)alpha.

Five hundred fifty-four suckled beef cows in three herds were allotted within postpartum interval to one of four treatments. All cows received two injections of prostaglandin F(2)alpha (PGF(2)alpha) 11 days apart. Treatment I served as a control. Calves were removed for 48 hr following the first injection of PGF(2)alpha in treatment II. Calves were removed similarly after the second injection of PGF(2)alpha in treatment III and after both injections of PGF(2)alpha in treatment IV. Pregnancy rates at the synchronized service, by 24 days and by 45 days of breeding were not (P>0.05) affected by treatment. Similarly, the treatments had no significant (P>0.05) effect on percentage of animals exhibiting estrus following the first and second injections of PGF(2)alpha.

Journal Article↗
PubMed1984

The timing of prednisolone dosage and its effect on morning stiffness in rheumatoid arthritis.

Forty-one patients with rheumatoid arthritis (RA) maintained on low dose prednisolone (mean 5.8 mg) participated in a double-blind cross-over study to determine the effect of timing (morning or night) of prednisolone dosage on morning stiffness. Prednisolone given at night resulted in a significantly shorter duration of morning stiffness (p = 0.0001) than did an equivalent dose given in the morning.

Adult↗
PubMed1983

Plasma levels and response to prednisolone therapy in rheumatoid arthritis.

Plasma prednisolone levels were measured in parallel with clinical and laboratory assessments in seven patients with rheumatoid arthritis on single daily doses of prednisolone which were reduced at weekly intervals from 10 mg. to 7, 6 and 5 mg. A significant negative rank correlation was observed between prednisolone dose and the duration of morning stiffness (p less than 0.05). No significant correlation was observed between plasma prednisolone levels, other clinical assessment criteria or laboratory indices.

Adult↗
PubMed1983

Heat distribution over normal and abnormal joints: thermal pattern and quantification.

We have identified regular thermal patterns over normal knee, ankle, and elbow joints and demonstrate how synovitis affecting these joints may be identified by alteration or loss of the thermal pattern. Sixty healthy volunteers were thermographed on a total of 190 occasions, and 614 out of 618 joints conformed to the normal thermal pattern. Eighty-five patients with synovitis of at least one of the specified joints were thermographed on a total of 339 occasions, and 322 out of 1362 thermograms were abnormal. No joint with clinical evidence of synovitis had a normal thermal pattern. As temperature-based parameters have been found to show marked diurnal variation and relative frequency distributions do not have this drawback, we suggest that quantification of synovitis by thermography should in future be based on abnormalities of thermal pattern rather than absolute skin temperature values.

Adolescent↗
PubMed1983

Luteal phase insufficiency in the ewe as a consequence of premature induction of ovulation by intrafollicular injection of gonadotropins.

The largest ovarian follicle of ewes was injected on d 15 of the estrous cycle (2 to 3 d before the anticipated preovulatory surge of gonadotropins) with saline or either luteinizing hormone (LH) or follicle-stimulating hormone (FSH) in saline (5 micrograms). Ovulation was assumed based on the presence of an ovulation stigma at d 5 post-treatment. Control animals expressed estrus 2 to 3 d after treatment with saline, and during the estrous period ovulated from the treated follicle. Gonadotropin-treated animals ovulated from injected follicles prematurely and did not exhibit estrus. The stated observations with respect to time of ovulation were established by visual and hormonal criteria: (1) control follicles appeared to have ruptured within a day or two prior to relaparotomy (corpora hemorrhagica), whereas gonadotropin-treated follicles were in a more advanced stage of luteal development (corpora lutea); and (2) concentrations of systemic sera progesterone rose (P less than .05) in LH- and FSH-treated ewes 2d before such an increase in control animals. Luteal function was assessed by comparing sera concentrations of progesterone throughout the induced and spontaneous (vehicle controls) luteal phases. Premature stimulation of ovulation with either gonadotropin was followed by suppressed luteal function (maximum sera levels of progesterone in gonadotropin-treated animals and controls were slightly greater than 1 ng/ml and nearly 2.5 ng/ml, respectively; P less than .01). No differences in the level of luteal function due to treatment with LH or FSH were observed. The duration of the luteal phases of gonadotropin-treated animals were similar to controls (approximately 17 d).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Serum cortisol and progesterone after administration of adrenocorticotropin and(or) prolactin to sheep.

An experiment was conducted to determine the effect of iv administration of adrenocorticotropin (ACTH) and(or) prolactin on serum cortisol and progesterone concentrations in hypophysectomized, ovariectomized, adult ewes. Twenty-four hours after surgery (d 1), six sheep were used in a crossover design and were assigned randomly to receive iv one of four treatments: (I) 200 IU ACTH in 10 ml .15 M NaCl at 0700 h, (II) 2.5 mg prolactin in 10 ml .15 M NaCl at 0700 h and again at 0730 h, (III) 200 IU ACTH and 2.5 mg prolactin in 10 ml .15 M NaCl at 0700 h followed by 2.5 mg prolactin in 10 ml .15 M NaCl at 0730 h, or (IV) 10 ml .15 M NaCl (vehicle) at 0700 and 0730 h. Blood samples (5 ml) were collected via jugular cannulae at 15-min intervals from 0600 to 0700 h and starting at 0700 h at 5, 10, 15, 30, 35, 40, 45, 60, 75, 90 and 120 min. Samples were then collected at hourly intervals until 1300 h. Twenty-four hours after commencement of first sampling (d 2), treatments were crossed and samples were collected as on d 1. Administration of ACTH alone or in combination with prolactin increased (P less than .01) serum cortisol and progesterone concentrations. Serum cortisol or progesterone concentrations were unaffected (P greater than .05) by administration of prolactin.

Adrenocorticotropic Hormone↗
PubMed1982

Identification of plasma kallikrein as an activator of latent collagenase in rheumatoid synovial fluid.

Rheumatoid synovial fluid contains an activator of latent collagenase from culture medium of pig synovium. The activator was purified by gel chromatography on Ultrogel AcA 44 and affinity chromatography on soybean trypsin inhibitor coupled to Sepharose 4B. The purified material was homogeneous on SDS-polyacrylamide gel electrophoresis with Mr 88 000. The activator had limited proteolytic activity against azo-casein, but showed amidase activity on Pro-Phe-Arg-NMec, Z-Phe-Arg-NMec, D-Val-Leu-Arg-NPhNO2 and D-Pro-Phe-Arg-NPhNO2, with an optimum at pH 8.0. Activity was completely inhibited by diisopropyl fluorophosphate, soybean trypsin inhibitor, leupeptin and Pro-Phe-Arg-CH2Cl, whereas lima bean trypsin inhibitor, Tos-Lys-CH2Cl, a specific inhibitor of factor XIIa from maize, EDTA and iodoacetate were not inhibitory. These properties of the activator suggested that it might be plasma kallikrein (EC 3.4.21.34), and the possibility was further examined. The activator was treated with [3H]diisopropyl fluorophosphate, and run in SDS-polyacrylamide gel electrophoresis with reduction; a radioautograph of the gel showed a pair of [3H]diisopropyl phosphoryl-labelled bands (Mr 36 000 and 34 000) identical to those obtained with authentic plasma kallikrein. Double immunodiffusion with monospecific antiserum against human plasma kallikrein confirmed the identification. This is the first demonstration of collagenase-activating activity of plasma kallikrein, and raises the possibility that activation of prokallikrein in the inflamed joint space may contribute to the disease process not only by the production of bradykinin, but also by activating latent collagenase.

Animals↗
PubMed1982

Rheumatoid lymphoedema.

Bilateral upper limb oedema due to lymphatic obstruction, is an uncommon complication of rheumatoid arthritis (R. A.). We report a case in which a 40 year old male with seropositive rheumatoid arthritis developed gross pitting oedema of the left arm. Lymphangiography showed lymphatic obstruction in both arms; within two months the right arm also became oedematous.

Adult↗