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Biomedical subjects

R D Baker

Publications and source records attributed to R D Baker.

At least 91 records · Page 5Linked to original sources
PubMed1977

Preprosthetic augmentation grafting--autogenous bone.

Alveolar bone graft augmentation has returned successful prosthetic denture function to patients with deficient alveolar ridges who were beyond the scope of treatment by preprosthetic soft tissue surgical procedures alone. The results of a 30.7-month mean postoperative follow-up of 15 patients with panoramic radiographs were recorded. Emphasis was placed on evaluation by functional improvement rather than on radiographic interpretation. Ideal results were not obtained in all instances; however, in the majority of cases, the patient benefitted by improved prosthetic function.

Alveoloplasty↗
PubMed1976

The effect of short chain fatty acids on transmural electrical potential across rat small intestine in vivo.

Short chain fatty acids suddenly produce a phasic increase in transmural electrical potential difference (PD) when placed in the lumen of rat small intestine in vivo. With concentrations of propionate ranging from 50 muM to 1000 muM the amplitude of the response in jejunum is about 5.5 mV. The concentration giving half this effect is about 20 muM. With 10 mM propionate the duration of the response is 3-5 min; after this, PD again equals the control value and the gut is refractory to further additions. Removing propionate from the mucosal surface produces no change in PD, but does restore responsiveness to subsequent exposure to short chain fatty acids. This effect is independent of a variety of other alterations in PD such as those caused by sugars, amino acids, bile salts, theophylline, prostaglandins, and ATP. Mechanism and significance of this surprisingly sensitive response remain obscure.

Animals↗
PubMed1976

Luteolytic activity of a synthetic prostaglandin and PGF2alpha in heifers.

Two experiments involving 44 cycling heifers were conducted to evaluate the luteolytic activity of a synthetic prostaglandin, AY 24366, and PGF2alpha. Activity was assessed by the decline in progesterone level of peripheral blood and occurrence of estrus. Progesterone concentrations of jugular blood plasma were quantified by radioimmunoassay. In the first experiment, 36 heifers were treated during diestrus with AY 24366 (A-10mg intrauterine, B-30mg intramuscular and C-60mg im) or with PGF2alpha (D-5mg iu, E-15mg im and F-30mg im). Mean progesterone 0, 24 and 48 hours after treatment were A-6.33, 5.55 and 5.06; B-6.35, 2.79 and 3.92; C-5.23, 2.69 and 3.91; D-5.19, 1.50 and 1.51; E-4.69, 0.85 and 0.61; F-6.66, 0.80 and 0.48 ng/ml. Standing estrus was observed in 1, 1, 1, 4, 5 and 6 females in groups A, B, C, D, E and F respectively within 72 hours of treatment. PGF2alpha resulted in significantly (P less than 0.01) lower progesterone at 24 and 48 hours than AY 24366. However, in administration of the latter did significantly (P less than 0.05) lower progesterone at 24 hours. In the second trial six heifers were treated with either 120 or 180mg of AY 24366 im on day 12 of the cycle. Mean progesterone declined from 3.84 to 2.12 ng/ml (P less than 0.01) by 6 hours and to 1.59 ng/ml by 12 hours. Thereafter the decline was gradual and reached a level of 0.65 ng/ml at 72 hours. All six heifers showed standing estrus at 78 +/-2 hours and were inseminated. Two in each group conceived. Doses of 15mg PGF2alpha and 120mg AY 24366 were effective in causing luteal regression, however, the latter caused respiratory discomfort for 5 to 10 minutes post treatment.

Animals↗
PubMed1976

The primary pulmonary lymph node complex of crytptococcosis.

A cryptococcal primary pulmonary lymph node complex has been demonstrated at autopsy or after thoracotomy in 1% of the cases of cryptococcosis. Stepwise microscopic examination of hilar lymph nodes should reveal a more frequent incidence of this rare but now well-documented complex. Nine examples of the cryptococcal complex are extant, including three herewith reported from the files of the Armed Forces Institute of Pathology. Four of these complexes developed in apparently normal persons and five in those hypersusceptible to infection because of neutropenia, diabetes, renal insufficiency, or corticosteroid therapy. The complexes in the normal persons were circumscribed granulomas and represented first-infection cryptococcosis similar to first-infection tuberculosis. There was a chronic course and a good prognosis with surgical resection. The complexes in the compromised hosts were predominantly acute diffuse pneumonias and large diffuse lesions of the lymph nodes, and were interpreted as first-infection cryptococcosis with massive spread facilitated by the compromised state. All these compromised patients died within a few weeks.

Adolescent↗
PubMed1976

Unilateral relapse after oblique osteotomy of the mandibular rami: report of case.

A case of unilateral relapse of mandibular prognathism after oblique osteotomy of the mandibular rami is described. A brief review of the pertinent literature is presented and a method of intraosseous fixation by Vitallium plating is illustrated. The need for close postoperative observations and reinstitution of active therapy at the first sign of a relapse tendency is emphasized.

Adult↗
PubMed1975

Sugar transport by intestine. Escape of galactose from preloaded mucosa of hamster jejunum.

Everted hamster jejunum was loaded with D-galactose and then escape into an initially galactose-free mucosal solution was followed. Mucosal anaerobiosis greatly increased the rate of escape, an effect which might have been caused by inhibiting reuptake from the unstirred layer and/or by augmenting the ease of unidirectional efflux across the brush border membrane. The former effect was expected because of our previous results from influx studies, and the main object here was to find out if the ease of efflux is affected by anaerobiosis. With phlorizin present in the mucosal solution during escape, information about unidirectional efflux was obtainable. We estimated that 10(-4) M phlorizin inhibited the ease of efflux via the phlorizin-sensitive pathway by about 65%. Apparently the reason why mucosal phlorizin accelerates escape of sugar from loaded mucosa, an effect which has been reported previously by others, is that it inhibits unidirectional efflux less effectively than it inhibits reuptake from the unstirred layer. Residual efflux via the phlorizin-sensitive pathway was markedly increased by mucosal anaerobiosis. This increase did not require an elevation of intracellular Na+ concentration. These results, together with those of our previous study, show that mucosal anaerobiosis abolishes uphill transport of galactose across the brush border of hamster jejunum by inhibiting unidirectional influx and by increasing the ease of unidirectional efflux. Neither of these effects requires a rise in intracellular Na+ concentration.

Anaerobiosis↗
PubMed1975

Pre-ovulatory changes in follicular fluid prostaglandin F levels in swine.

The concentration of prostaglandin F (PGF) has been measured by radioimmunoassay in follicular fluid collected from follicles at various time intervals after treatment of prepuberal gilts with pregnant mare serum gonadotropin and human chorionic gonadotropin to induce ovulation. A high proportion of animals will ovulate 116 +/- 8 hr after treatment. Pre-ovulatory follicles can be identified on the basis of gross morphological apperance 10-12 hr before the predicted time of ovulation. The concentration of PGF in fluid from follicles judged not to be pre-ovulatory was relatively constant at about 0.45 ng per g and appeared to be independent of the time of sampling. An increase in the concentration of PGF was observed in fluid collected from follicles classified as destined to ovulate. This increase became more pronounced as the time of ovulation approached and reached a maximum at or about the time of follicle rupture. These data provide evidence in support of a role for prostaglandins in the ovulatory process in the pib.

Animals↗
PubMed1975

Human follicular oocytes and their maturation in vitro.

To study the maturation of follicular oocytes, germ cells were flushed from visible follicles in the ovaries of 145 oophorectomized patients 17 to 65 years of age. The number of oocytes recovered decreased (P less than 0.05) as patient age increased. More oocytes (P less than 0.05) were recovered from ovaries removed during the proliferative stage of the menstrual cycle than during the secretory stage. Of 776 oocytes obtained, 132 (17%) were examined without incubation. Two had matured in vivo and another possessed two vesicular nuclei. Of 124 oocytes incubated in tissue culture Medium 199 or Ham's F10 supplemented with 10% fetal calf serum, 52 (42%) displayed germinal vesicle breakdown and 39 (31%) progressed to metaphase of the second meiotic division within 42 hours. Neither the stage of the cycle at which ovaries were removed nor the addition of progesterone to the medium had a significant effect on maturation. The rate of maturation peaked with oocytes from women 34 to 39 years of age. Even though more oocytes were recovered from patients 17 to 33 years of age than from patients 34 to 39 years, fewer oocytes obtained from the younger patients appeared to be viable, perhaps because of a greater incidence of ovarian follicle pathology in the youngest group.

Adolescent↗
PubMed1975

Formation of steroids by the pregnant mare. V. Metabolism of 14C-isopentenylpyrophosphate and 3H-dehydroisoandrosterone injected into the fetus.

A mixture of 1-14C-isopentenylpyrophosphate and 3H-dehydroisoandrosterone was injected into a horse fetus intramuscularly during laparotomy, after which maternal urine was collected for 4 days. Steroid conjugates in the urine were extracted with Amberlite XAD-2 resin, hydrolysed and separated into phenolic and neutral fractions. From the phenolic fraction estrone, 17alpha-estradiol, equilin and equilenin were isolated. Only estrone and 17alpha-estradiol contained both 3H and 14C, while the ring B unsaturated estrogens contained only 14C. From the neutral fraction 14C-labeled 3beta-hydroxy-5alpha-pregnan-20-one, 5alpha-pregnane-3beta,20beta-diol and 5alpha-pregnan-3beta, 20alpha-diol were isolated. These results demonstrate that the route of biosynthesis of both the ring B saturated and unsaturated estrogens is the same up to the stage of isopentenylpyrophosphate. Thus, the bifurcation in the classical pathway of steroid biosynthesis reported previously by us is occurring at a point after the formation of isopentenylpyrophosphate and prior to the formation of squalene.

17-Ketosteroids↗