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Biomedical subjects

M E Boyd

Publications and source records attributed to M E Boyd.

At least 37 records · Page 2Linked to original sources
PubMed1987

Importance of the duration of inhibition on intestinal carcinogenesis by difluoromethylornithine in rats.

The effect of the duration and sequence of inhibition of intestinal tumor formation in rats was studied to determine whether part time inhibition has any value. Four groups of male Sprague-Dawley rats were given 8 weekly s.c. injections of azoxymethane (AOM) 8 mg/rat. Three groups were given the inhibitor, difluoromethylornithine (DFMO) in the drinking water; one for the entire 26 weeks of the study, one for the first 13 weeks only, and one for the last 13 weeks. A control group was not given the inhibitor. While the continuous treatment group developed the least number of tumors per rat (1.5 vs. 5 for controls), still both groups given the inhibitor for just 13 weeks also developed fewer tumors than controls 5 vs. 3.2 (early treatment) and 5 vs. 2.8 (late treatment). These results show that part time inhibition, including its late application, does reduce intestinal tumor formation in rats.

Animals↗
PubMed1987

Care of the ureter in pelvic surgery.

Maintaining the integrity of the ureter is crucial in pelvic surgery. The ureter is best safeguarded by routine intraoperative exposure, which will also allow immediate recognition of injury to it. If doubts over possible injury persist, it is best to open the bladder. The flux of urine from the ureteric orifices or the retrograde passage of catheters will then confirm or deny clinical suspicions. If specialist help is unavailable, the pelvic surgeon must be able to perform simple ureteric repairs or temporize in a way that allows the safe delay of definitive surgery. End-to-end ureteric anastomosis and ureteroneocystostomy are straight-forward procedures that all pelvic surgeons should be familiar with. If they cannot be performed safely, the situation may be salvaged by draining the proximal ureter through the lateral abdominal wall; later, definitive surgery can be performed.

Female↗
PubMed1987

Stress incontinence of urine.

At rest, continence of urine depends on intraurethral pressure being higher than intravesical pressure. Intraurethral pressure is produced by elastic fibres and engorged urethral venous sinuses. Low intravesical pressure is preserved by bladder muscle relaxation. Urgency incontinence will result if bladder muscle does not relax. A sudden increase in abdominal pressure may overcome this urethral-vesical pressure gradient and cause stress incontinence. The mechanisms that prevent this from happening are unclear. The pressure gradient would not change if the abdominal pressure was transmitted equally to the urethra and the bladder. Continence could also be protected by pressure of the urethra against the symphysis pubis or pelvic muscles. Stress and urgency incontinence cannot be differentiated clinically with certainty. If surgical correction of stress incontinence is planned, preoperative urethrocystometry is mandatory. The Burch colposuspension is the operative procedure of choice. The suspension is done with Prolene sutures; their correct placement is ensured through the use of intraoperative cystostomy.

Female↗
PubMed1987

Postoperative gynecologic infections.

Postoperative gynecologic infections are caused by mixed aerobic and anaerobic bacteria that normally reside in the vagina. For the most part the infection, manifested by fever, resolves spontaneously, but occasionally serious problems result. Opinion now favours the prophylactic use of antibiotics before both abdominal and vaginal hysterectomy. Established infections are first treated with a combination of clindamycin and gentamicin.

Abscess↗
PubMed1986

Reproductive performance of postpartum beef cows after short-term calf separation and dietary energy and protein supplementation.

Beef cows (n = 294) calving between November and April in six states were used to evaluate the effects of postpartum diet and calf separation on body weight, body condition score (BCS), reproductive performance, and weaning weight of calves. In each state, half of the 48 cows that calved during 60 d were group fed an additional 4.5 kg of a 20% crude protein supplement daily for 28 d starting an average of 30 d post partum (flush). Calves were separated from half of the flush and half of the nonflush cows for 48 h at 14 and 28 d after the beginning of flush. Progesterone was quantified in plasma samples obtained weekly during a 56-d breeding period to assess ovarian luteal activity. The breeding period started at the first calf separation. BCS ranged from 3.3 to 5.6 among states (on a scale of 1 to 9) at the start of the flush but was similar for treatments within a state. There was a state x flush (P < 0.008) effect on body weight at the end of the flush period. Weaning weights were influenced by state x separation x flush (P < 0.06) and were greatest for flush nonseparated calves in five of six states. There were state x flush (P < 0.08) and separation (P < 0.04) effects on ovarian luteal activity at the start of the breeding period. Flush and separation tended to increase ovarian luteal activity. During the breeding period, ovarian luteal activity was influenced only by state but there was a state x separation x flush effect (P < 0.001) on the number of weeks post partum to onset of ovarian luteal activity. Conception rate and days postpartum to conception were not influenced by either separation or flush but were affected by state (P < 0.001). These data indicate that flushing may increase weaning weights of calves and calf separation may hasten the onset of postpartum ovarian luteal activity, but conception rate and days postpartum to conception for cows in thin to moderate body condition were not influenced by the calf separation or flushing treatments.

Journal Article↗
PubMed1986

Dysfunctional uterine bleeding.

Dysfunctional uterine bleeding is defined as abnormal uterine bleeding in the absence of organic disease. It is the result of anovulation or the abnormal local production of prostaglandins, and in each case the primary fault is inappropriate hormone formation. There are two approaches to diagnosis. The traditional one is primarily concerned with the exclusion of cancer of the endometrium; this concern results in the frequent resort to uterine curettage. The second approach is to limit curettage to patients whose symptoms are not ameliorated by medical therapy. The aim of medical treatment is either to produce secretory change in the endometrium or to decrease the formation of uterine prostaglandins. Intermittent progesterone treatment is used to cause secretory changes in the endometrium. Decreased production of the prostaglandins is achieved indirectly by causing atrophy of the endometrium or directly through the use of prostaglandin synthetase inhibitors. Surgery in the form of dilatation and curettage has no long-term therapeutic effect; hysterectomy is definitive therapy.

Adult↗
PubMed1986

Inhibition of intestinal carcinogenesis in rats: effect of difluoromethylornithine with piroxicam or fish oil.

An inhibitor of ornithine decarboxylase, difluoromethylornithine (DFMO), and two inhibitors of prostaglandin biosynthesis, piroxicam and menhaden fish oil, were examined for their effect on intestinal tumorigenesis in male Sprague-Dawley rats fed a 5% fat semisynthetic diet. Each agent was given individually in one of two doses as follows: DFMO, 0.05% and 0.1% in the drinking water; piroxicam, 65 mg/kg diet and 130 mg/kg diet; and menhaden fish oil, 1.25% and 2.50% of the diet. Additional animal groups were given combinations of the lower dose of DFMO and the lower dose of either piroxicam or fish oil. Intestinal tumors were induced by sc injections of azoxymethane (AOM; CAS: 25843-45-2) at 8 mg/kg (body wt) weekly for 8 weeks. Test diets were started 1 week prior to the first dose of AOM, and the rats were sacrificed 26 weeks later. Rats that received either dose of DFMO or the high dose of piroxicam developed significantly fewer intestinal tumors compared to controls. The low dose of piroxicam and the fish oil given at either dose level had no effect. The combination of the low dose of DFMO and the low dose of piroxicam reduced tumor formation more than either dose of DFMO alone, whereas the low dose of DFMO and fish oil together was no more effective than either dose of DFMO alone. These results show that a combination of a small amount of DFMO and piroxicam, each acting through a different mechanism, exerts an additive inhibitory effect on intestinal tumor formation in rats.

Animals↗
PubMed1986

Myomectomy.

If fibroids require treatment, hysterectomy is usually the therapy of choice. Myomectomy is best reserved for women who wish to preserve their uterus and have a single large fibroid tumour; it is not normally recommended for either abnormal uterine bleeding or infertility. The blood supply of leiomyomas is from the periphery and is such that degeneration frequently ensues. Degeneration, in particular the acute degeneration that may occur in pregnancy, is rarely an indication for operation. Myomectomy has been associated with considerable blood loss intraoperatively and prolonged morbidity postoperatively. The former can be avoided by limiting the uterine circulation during surgery with a uterine tourniquet and vascular clamps. Atraumatic intracapsular removal of the tumour and perfect hemostasis will minimize the latter.

Female↗
PubMed1986

Failed forceps.

Among 53 cases of failed forceps occurring in 6524 uncomplicated primiparous deliveries, depression at birth and encephalopathy occurred with similar frequency as when cesarean section was done for failure to progress in the second stage, and birth trauma was no more common than that with successful midforceps delivery. Factors predisposing to or associated with midforceps deliveries or second stage cesarean sections were short mothers, heavy babies, induced or prolonged labors, and fetal distress or meconium release in labor.

Cesarean Section↗
PubMed1985

Ectopic pregnancy.

Ectopic pregnancy is no longer dependent on laparotomy for definitive diagnosis. When patients present with massive hemoperitoneum, the diagnosis is usually obvious; but most patients do not present this way, so diagnostic aids are required. Culdocentesis is associated with unusually high false-negative and false-positive results. Laparoscopy is accurate but is an invasive procedure unwarranted in most cases for diagnosis. Although it is unusual to make the diagnosis of unruptured ectopic pregnancy by ultrasonography alone, when ultrasonography is combined with quantitative beta-subunit determinations of human chorionic gonadotropin, many ectopic pregnancies can be diagnosed before rupture occurs. The treatment of the woman with a ruptured ectopic pregnancy and in shock is immediate laparotomy and salpingectomy. Salpingostomy with removal of the ectopic mass and preservation of the tube may enhance a patient's subsequent fertility and may be useful in carefully selected women.

Diagnosis, Differential↗
PubMed1985

Endometriosis.

Endometriosis is related to retrograde menstruation or coelomic metaplasia and depends on the presence of estrogen. It is a consequence of menstruation into an area that has no outlet for menstrual blood. As a result, antigenic substances are released, causing an inflammatory response and the formation of prostaglandins. Subsequent inflammatory repair distorts pelvic anatomy and the prostaglandins affect ovarian, tubal and uterine function. Symptoms are not specific, so definitive diagnosis depends on laparoscopy or laparotomy for confirmation. Medical therapy is aimed at reducing the estrogen on which the endometriotic lesions depend. Danazol, a testosterone derivative, does this by interfering with ovarian follicular development, and often results in both symptomatic and objective improvement. When therapy is withdrawn, the renewed estrogen stimulus may cause the lesions to recur. Conservative surgical therapy (the excision of endometriotic nodules and the restoration of pelvic anatomy while leaving a reproductive potential) is equally successful. Radical surgery (abdominal hysterectomy and bilateral salpingo-oophorectomy) is definitive, removing both the stimulus for endometriotic growth and the source of renewal.

Combined Modality Therapy↗
PubMed1985

Pelvic inflammatory disease and the general surgeon.

New causal agents of pelvic inflammatory disease that have recently been determined are Chlamydia trachomatis, anaerobic bacteria and penicillinase-producing gonococci. It is also recognized that the pelvic infection is normally polybacterial. The symptoms produced by these organisms are so indefinite that diagnosis based on clinical findings alone is often difficult. The diagnosis of pelvic inflammatory disease should therefore be established by laparoscopy in these cases. Antibiotics capable of eradicating most pelvic infections are now available. As a result of their use, the primary therapy has become medical. The indication for surgery is, in essence, failed medical therapy. Ablative surgery should generally be delayed until adequate antibiotic therapy has been tried and found inadequate. Furthermore, the surgery should be conservative because the disease is often unilateral. Total abdominal hysterectomy and bilateral salpingo-oophorectomy as a treatment for pelvic inflammatory disease should be the exception rather than the rule.

Anti-Bacterial Agents↗
PubMed1985

Ovarian cancer.

The behaviour of epithelial cancer of the ovary differs from that of other epithelial tumours that the general surgeon normally contends with for the following reasons: first, it often responds well to incomplete surgery as it is frequently sensitive to chemotherapy and, second, its method of spread is unique. Proper treatment of this lesion must take these characteristics into account. Immediate therapy is excision of the tumour mass and its principal metastases. This normally includes removing the uterus and its adnexae plus the omentum. Only when the remaining tumour masses are small will postoperative chemotherapy be effective. Moreover, the chemotherapy can only be given rationally if the extent of dissemination of the disease is carefully defined. The spread of this malignant tumour is most often by way of free-floating cells in the peritoneal cavity. The tumour cells subsequently deposit in "watersheds" throughout the peritoneal cavity and accumulate on the undersurface of the diaphragm and in the omentum. Staging, which describes this process and its variations, is therefore of great importance and is described in this paper in detail.

Carcinoma↗
PubMed1983

Fetal macrosomia: prediction, risks, proposed management.

The outcome of delivery of infants weighing more than 4000 g born during two time periods 15 years apart was studied retrospectively. The increased use of cesarean section and other obstetric advances did not reduce the risk of fetal asphyxia and trauma associated with large fetal size. Maternal factors were identified for risk categorization of fetal macrosomia during pregnancy. Macrosomia was rare at 37 weeks and increasingly common thereafter. Fetal size assessment by ultrasound at 36 to 38 weeks' gestation would permit induction of labor for the macrosomic infant before the size became excessive or would make the accoucheur aware of the dangers that may arise during delivery.

Adult↗
PubMed1981

In vitro reversal of the fasting state of liver metabolism in the rat. Reevaluation of the roles of insulin and glucose.

Studies were conducted to determine whether the direction of hepatic carbohydrate and lipid metabolism in the rat could be switched simultaneously from a "fasted" to a "fed" profile in vitro. When incubated for 2 h under appropriate conditions hepatocytes from fasted animals could be induced to synthesize glycogen at in vivo rates. There was concomitant marked elevation of the tissue malonyl-coenzyme A level, acceleration of fatty acid synthesis, and suppression of fatty acid oxidation and ketogenesis. In agreement with reports from some laboratories, but contrary to popular belief, glucose was not taken up efficiently by the cells and was thus a poor substrate for eigher glycogen synthesis or lipogenesis. The best precursor for glycogen formation was fructose, whereas lactate (pyruvate) was most efficient in lipogenesis. In both case the addition of glucose to the gluconeogenic substrates was stimulatory, the highest rates being obtained with the further inclusion of glutamine. Insulin was neither necessary for, nor did it stimulate, glycogen deposition or fatty acid synthesis under favorable substrate conditions. Glucagon at physiological concentrations inhibited both glycogen formation and fatty acid synthesis. Insulin readily reversed the effects of glucagon in the submaximal range of its concentration curve. The following conclusions were drawn. First, the fasted-to-fed transition of hepatic carbohydrate and lipid metabolism can be accomplished in vitro over a time frame similar to that operative in vivo. Second, reversal appears to be a substrate-driven phenomenon, in that insulin is not required. Third, unless an unidentified factor (present in protal blood during feeding) facilitates the uptake of glucose by liver it seems unlikely that glucose is the immediate precursor for liver glycogen or fat synthesis in vivo. A likely candidate for the primary substrate in both processes is lactate, which is rapidly formed from glucose by the small intestine and peripheral tissues. Fructose and amino acids may also contribute. Fourth, the requirement for insulin in the reversal of the fasting state of liver metabolism in vivo can best be explained by its ability to offset the catabolic actions of glucagon.

Animals↗
PubMed1979

Prolonged amenorrhea and oral contraceptives.

Of 106 consecutive women referred for secondary amenorrhea of more than 1 year's duration, 65 were diagnosed as having functional amenorrhea. Of these 65, 29 had amenorrhea directly following discontinuation of oral contraceptives (OC group) and 36 had never used oral contraceptives (NOC group). There was no difference in the incidence of prior menstrual irregularity in either group. Similarly, there was no difference in the resting serum estrone, estradiol, luteinizing hormone, follicle-stimulating hormone, and prolactin levels between the OC and NOC groups. Nor was there a difference between the OC and NOC groups in response to medroxyprogesterone acetate, clomiphene citrate, or luteinizing hormone-releasing factor. Of 106 patients, 17 were proven to have prolactinomas. Eight patients had a prior history of OC use, whereas nine did not. With the exception of elevated serum prolactin levels, there were no significant differences in biochemical tests or history of oral contraceptive use between the prolactinoma group and patients with prolonged "functional" amenorrhea (OC plus NOC groups). The lack of historical or biochemical difference between the OC and NOC subjects indicates homogeneity between groups, and does not support the existence of a "postpill" syndrome.

Adult↗