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Biomedical subjects

D M Smith

Publications and source records attributed to D M Smith.

At least 433 records · Page 24Linked to original sources
PubMed1975

Failure of gonadotropins to induce in vitro maturation of mouse oocytes treated with dibutyryl cyclic AMP.

In sufficient concentration, dibutyryl cAMP (DBC) prevents the spontaneous in vitro maturation of mouse oocytes. The effects of luteinizing hormone (LH) and follicle stimulating hormone (FSH) on this inhibition were tested in an oil-free chamber-slide culture system. Mouse oocytes devoid of cumulus cells were incubated in the presence of DBC and/or gonadotropins. Oocytes cultured with follicle cells were similarly treated. Whether follicle cells were present or absent, DBC (100 or 500 mug/ml) prevented germinal vesicle breakdown in more than 95% of the oocytes cultured. Neither LH nor FSH in a wide range of concentrations acted directly on the oocytes or indirectly through the follicle cells to initiate maturation in oocytes incubated with 100 mug DBC/ml. The combination of LH (5 mug/ml) and FSH (10 mug/ml) was also ineffective in overcoming the block induced by either 100 or 50 mug DBC/ml. Maturation of oocytes in each of the DBC-free LH or FSH treatments was comparable to that occurring in control medium which did not contain exogenous gonadotropins or DBC. It was concluded that cultured oocytes treated with DBC are not a satisfactory model for studying the steps by which gonadotropins trigger the resumption of meiosis in mammalian oocytes.

Animals↗
PubMed1975

Coracoid fracture associated with acromioclavicular dislocation. A case report.

When a fracture of the coracoid process is identified by clinical examination and X-rays, one should always be aware of a possible acromioclavicular dislocation. Clinical exam and X-rays of the shoulder with weights in the patient's hand will help substantiate the diagnosis. Reduction of the acromioclavicular dislocation (by whatever means desirable) seems to reduce the coracoid fracture well. Obviously, this combination of injuries precludes the use of coracoclavicular methods of fixation as a method of treatment. Acromioclavicular joint reduction and secure internal fixation generally provides adequate coracoid fracture reduction and allows subsequent healing.

Acromioclavicular Joint↗
PubMed1975

An investigation into the cardiac and pulmonary beta-adrenoceptor blocking activity of ICI 66,082 in man.

1 Oral ICI 66,082 (200 mg) or water (control treatment) were each administered to six healthy volunteers. 2 The heart rate (HR) and peak flow rate (PFR) were measured at rest and during vigorous exercise before and at intervals up to 24 h after each treatment. 3 ICI 66,082 produced significant reductions in exercise HR at all times compared with the changes after the control treatment (P less than 0.001), whereas with resting HR, corresponding significant reductions only occurred at 2,3 and 4 h (P less than 0.05). 4 Although there was no change in resting PFR, significant reductions in exercise PFR, compared with the changes after the control treatment, occurred at all times excepting at 2 h after ICI 66,082 (P less than 0.025). 5 The findings are consistent with ICI 66,082 possessing partial cardioselectivity. 6 Plasma levels and renal excretion of the drug were determined. Urinary recovery was variable which, together with the plasma concentration/effect relationships obtained, raise the possibility that ICI 66,082 is metabolized in man.

Adult↗
PubMed1975

A system to regulate aortic pressure in the rat.

A servo-controlled aortic clamp has been designed and used for the first time in the anesthetized rat to control femoral arterial pressure. An electrical schematic is given and details of the mechanical clamp used to compress the abdominal aorta are shown. The system has a long-term (30 min) mean pressure control of plus or minus 2 mmHg although some 1-2 s transients of plus or minus 3 mm may occur. It responds to a desired step change in pressure in less than 2 s. The system allows accurate and convenient control of aortic pressure and minimizes the technical difficulties encountered when one attempts similar control by manual means. It therefore facilitates investigation of the effect of transient or steady-state changes in arterial pressure on organ function, e.g., autoregulation of renal blood flow and glomerular filtration rate.

Animals↗
PubMed1975

The loss of bone mineral with aging and its relationship to risk of fracture.

Longitudinal studies have shown that individuals lose bone mineral at unequal rates with aging. It has been postulated that individuals with the more rapid rates of loss constitute a separate population having an increased risk for developing fractures, i.e., osteoporosis. To examine this postulate, we made a search for a separate population of elderly women using a precise and objective measurement technique of bone mineral, photon absorptiometry. Bone mineral content (BMC) was measured in the radius of 571 Caucasian females who were age 50 or older. It was found that BMC values adjusted for width had a normal distribution in all decades and the variation in BMC values did not increase with age. Subjects with vertebral fractures (n = 108) were estimated to be losing bone mineral at the same rate as those without vertebral fractures (n= 161). Thus evidence for a separate population of rapid losers of bone mineral was not found. Reconciliation of longitudinal studies which show unequal rates of loss with the present population survey, in which evidence for unequal rates was not found, would require that (a) the rate of loss of bone mineral for an individual is not constant and/or (b) the rate of mineral loss is proportional to the amount of mineral present at maturity. The incidence of vertebral fractures was inversely proportional to BMC values. In a group of 278 women followed for 470 subject-yr, the incidence of all fractures during the study (n = 31) was also inversely proportional to BMC. These data suggest that the BMC values of osteoporotics would be at the lower end of normally distributed values for the population.

Adult↗
PubMed1975

Cyclic 3', 5'-adenosine monophosphate levels in separated bone cells.

It has been shown that both parathyroid hormone (PTH) and calcitonin (CT) increase the concentration of cyclic 3',5'-adenosine monophosphate (cyclic AMP) in skeletal tissue. Since these two hormones have opposing actions on bone resorption, it has been postulated that the cell types upon which the hormones act in skeletal tissue may be different. We have previously shown that osteoblasts and osteocytes contain adenylate cyclase responsive to both PTH and CT whereas the enzyme prepared from periosteum and marrow cells did not respond to either. To further examine the postulate, the effect of these hormones on the concentration of cyclic AMP was determined. Bovine PTH (5U/ml equal to 4.2 times 10-7M) significantly increased the concentration of cyclic AMP/mug DNA in periosteum, osteoblasts, and osteocytes but not in marrow cells. Porcine CT (0.5 U/ml equal to 8.0 mug/ml approximately equal to 3.0 times 10-6M) significantly increased the concentration of cyclic AMP/mug DNA in periosteum, osteoblasts, osteocytes, and marrow cells. Adenylate cyclase activity prepared from periosteum and marrow cells was re-examined using EGTA and DMSO to improve enzyme stability and activity. Wth these additions PTH (5 U/70 mul) increased activity of the preparation from periosteum, and CT (0.5 U/70 mul) increased activity from marrow cells and periosteum. These studies provide evidence that: 1) periosteum, osteoblasts, and osteocytes respond directly to both PTH and CT and 2) marrow cells respond to CT and not PTH.

Animals↗
PubMed1975

Complications of Austin Moore arthroplasty. Their incidence and relationship to potential predisposing factors.

In a retrospective computerized study of 451 Austin Moore arthroplasties (211 for acute hip fractures and 240 for hip reconstruction), the operative and general complications were correlated with the historical, preoperative, operative, and early and late postoperative factors usually thought to influence the results. Wound complications were significantly associated with diabetes and fracture, obesity and fracture, and procedures lasting two hours or more. General complications showing significant associations were: death or pneumonia with fractures, phlebitis with obesity, and myocardial infarction with fracture. Factors not significantly associated with complications included age, previous hip surgery, time of day of the operation, surgical approach, wound irrigation, use of drains, postoperative anticoagulation, and reaming of the acetabulum.

Acute Disease↗
PubMed1975

Splenic mediated erythrocyte cytotoxicity in malaria.

Cell-mediated cytotoxicity in virulent rodent malaria has been demonstrated in vitro, whereby splenic cells effected specific lysis of 51Cr-labelled erythrocytes from parasitized animals. More than one cellular cytolytic effector system appeared to be operative in the mouse. One effector system involved splenic macrophages, from normal or immune animals, which were increasingly cytotoxic to target cells in the presence of antibody. A second effector system involved nylonpurified immune spleen cells which were significantly more cytotoxic than similary prepared normal spleen cells in the presence of immune serum. Although antibody alone was not cytolytic, the data strengthen the concept that immune spleen cells and antibody can interact in a co-operative fashion to mediate cytotoxic reactions in malaria.

Animals↗
PubMed1975

Vitamin A and benzo(a)pyrene carcinogenesis in the respiratory tract of hamsters fed a semisynthetic diet.

Male Syrian golden hamsters were fed a semisynthetic diet, given 12 weekly intratracheal instillation of 3 mg benzo(a)pyrene adherent to 3 mg Fe2O3, and then given either 100, 1600, or 2400 mu-g retinyl acetate (RA) per week intragastrically in 2 divided doses. One-half of the animals in each group were housed conventionally; the other half were housed in laminar flow units. Hepatic and serum vitamin A levels were markedly increased in hamsters given 1600 or 2400 mu-g RA per week compared to controls given 100 mu-g, which is adequate for growth and maintenance. In hamsters housed conventionally, increased RA intake was associated with an increased incidence of benign respiratory tract tumors. In all groups of hamster housed in laminar flow units there was a longer period to death with respiratory tract tumor than in conventionally housed hamsters; increased RA intake was associated with a somewhat lower incidence of respiratory tract tumors. Laminar flow housing significantly reduced the incidence of respiratory tract infection in non-tumor-bearing hamsters. Squamous papillomas of the forestomach were significantly reduced in all groups of hamsters given high levels of RA, regardless of housing.

Animals↗
PubMed1975

Postnatal growth of the dog heart.

We have found that, in the dog at birth, the right ventricle weighed significantly more than the left. At 3 days the left ventricle weighed the same as the right ventricle. No evidence for postnatal atrophy of the right ventricle was found--the right ventricle simply gained weight at a much slower rate than the left. The left ventricle weighed significantly more than the right at 7,9,11,13,15 and 17 days.

Age Factors↗
PubMed1975

Laparoscopic recovery of mature human oocytes.

This report provides a detailed description of a method by which mature or maturing human oocytes can safely be recovered by follicular aspiration during laparoscopy. By combining gonadotropin administration with laparoscopic recovery, oocytes which have resumed or completed meiotic division can be obtained for study without subjecting the patient to more hazardous surgical procedures. Fifteen oocytes were obtained from sixteen patients. On electron microscopic examination, four were found to have extruded polar bodies and were therefore classified as mature. Daily rather than intermittent administration of HMG, larger HMG dose, longer HCG aspiration intervals, and controlled aspiration pressures appeared to be the factors which produced the best yield of mature oocytes.

Adult↗
PubMed1975

Vitamin A (retinyl acetate) and benzo(alpha)pyrene-induced respiratory tract carcinogenesis in hamsters fed a commercial diet.

Male Syrian hamsters fed a commercial diet were given a series of 12 intratracheal instillations of 3 mg benzo (alpha) pyrene adherent to 3 mg Fe2O3 in 0.2 ml 0.15 M NaCl at weekly intervals. After the last instillation, the hamsters were randomly assigned to receive either 100, 1600, or 3300 (later reduced to 2400) mug retinyl acetate per week in divided intragastric doses. Hamsters in the 2400-mug retinyl acetate group had a significantly higher incidence of respiratory tract tumors than those in the group given 100 mug retinyl acetate per week. Liver vitamin A stores increased dramatically in the groups given 1600 and 2400 mug retinyl acetate and corresponded to the administration of retinyl acetate p.o. Serum vitamin A values were not consistently related to retinyl acetate administration or to hepatic stores of vitamin A.

Adenocarcinoma↗
PubMed1974

New approach to assessment of cardioselectivity of beta-blocking drugs.

Propranolol, practolol, and placebo were each given intravenously at weekly intervals to six normal subjects, and their effects on respiratory function tests and heart rates assessed. The reduction in the exercise heart rate after each of the two drugs was most comparable at six hours, indicating a similar degree of cardiac beta-blockade, when the plasma concentration ratio of practolol to propranolol was 28:1. The peak flow rate (PFR) was higher at all times during exercise than at rest. There were significant differences between the changes in resting and exercise PFR after placebo and the reductions after propranolol (except at 24 hours), but not after practolol-and the latter's influence on PFR seemed to be intermediate to that of propranolol and placebo. At six hours, when the cardiac beta-blocking activity of the two drugs was almost the same, there was a significant difference (P 0.025) between the reductions in exercise PFR associated with each drug.

Adult↗