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Biomedical subjects

R Martin

Publications and source records attributed to R Martin.

At least 577 records · Page 32Linked to original sources
PubMed1986

Ultrasound and the intestinal wall: experimental methods.

High-frequency, high-resolution ultrasound provides a new approach to imaging structures in the wall of the gastrointestinal tract. Questions about internal ultrasound include: is the ultrasound image specific for disease states, in which diseases will this technology add new and useful information not available from existing diagnostic studies, and what are the necessary characteristics for a system to accomplish these diagnoses? Answering these questions requires that precise correlations be made between the ultrasound image and pathology. We have developed a method to image a resected gastrointestinal tissue with ultrasound and to remove and examine the corresponding piece of tissue histologically. Changes in wall thickness, obliteration of layers, and changes in the characteristics of the tissue can be studied. We have shown that ultrasound can resolve the layers of the gut wall. This system should enable us to answer questions about which intestinal wall diseases are suitable for internal ultrasound imaging and characterize the engineering features of an optimal ultrasound system for clinical application.

Digestive System↗
PubMed1986

The use of clonidine in the treatment of neuroleptic-induced tardive dyskinesia.

A double-blind crossover comparison of clonidine and placebo was conducted in seven subjects afflicted with neuroleptic-induced tardive dyskinesia (TD). Subjects received either clonidine, 0.4 mg/day, or placebo for a period of 8 weeks and were then crossed over to the opposing treatment modality. The effects of clonidine on TD symptomatology could not be distinguished from those of placebo (p greater than 0.05). However, comparison of prestudy ratings of TD severity to poststudy ratings revealed a significant reduction in TD symptoms (p less than 0.01). Close analysis of the data indicates that clonidine's effect on TD may have carried over into the placebo phase of the study, masking any true differences between clonidine and placebo treatment. Other factors which may have contributed to the lack of significant findings are discussed.

Adult↗
PubMed1986

Results of adjuvant chemotherapy trials in breast cancer at M. D. Anderson Hospital and Tumor Institute.

Between 1974 and 1982, 796 patients with operable breast cancer following local therapy were treated with 3 consecutive doxorubicin-containing adjuvant therapy trials. The median follow-up of patients entered on the first trial was 102 months; the second trial, 71 months; and for the third trial, 41 months. The treatment program consisted of 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC). We altered the study designs to determine the role of nonspecific immunotherapy with BCG and postoperative irradiation in the second trial and the impact of additional chemotherapy with alternate drugs after completion of FAC in the third trial. In the first study, an overall 39% reduction in mortality was observed, and, in stage II disease, reductions of 54% and 37% in mortality were observed for patients less than 50 and greater than or equal to 50 years of age, respectively, in comparison to the historical control group. The data of the second trial illustrated that BCG and postoperative irradiation had no significant impact on the disease-free and overall survival. In the third trial, patients with estrogen receptor-positive tumor treated with additional chemotherapy with alternate drugs following completion of FAC had significantly superior disease-free survival compared with patients who did not receive additional chemotherapy. The results of 3 studies show that intensive combination chemotherapy significantly reduced the risk of recurrence and death in patients with breast cancer.

Adult↗
PubMed1985

Synthetic substrates of vertebrate collagenase.

The active site specificity of vertebrate collagenase was mapped with the synthesis of a variety of peptides, peptolides, and peptide esters. The enzyme was found to prefer very lipophilic sequences, and it was also found to be an esterase. The thio peptolide Ac-Pro-Leu-Gly-SCH[CH2CH(CH3)2]CO-Leu-Gly-OC2H5 was found to be an exceptional substrate. High-performance liquid chromatography and tandem mass spectrometry were used to unambiguously establish the cleavage site in several peptide substrates.

Animals↗
PubMed1985

Opioid binding in a rat neurohypophysial fraction enriched in oxytocin and vasopressin nerve endings.

Binding of the opiate antagonists [3H]diprenorphine and [3H]naloxone and of the opioid agonists [3H]Met-enkephalin and [3H]dynorphin(1-8) was studied in a fraction of the rat neurohypophysis containing disconnected oxytocin and vasopressin nerve endings ('neurosecretosomes'). There was specific binding of [3H]diprenorphine in the fraction enriched with neurosecretosomes. This binding was only partially displaceable by naloxone; naloxone binding was stereospecific. Intact and unoxidized [3H]Met-enkephalin was found in the neurosecretosome pellet; binding of the analogue D-Ala-D-Leu-enkephalin was very low. Our data favour the assumption of a direct action of endogenous opioids at the neurosecretory nerve endings.

Animals↗
PubMed1985

An objective assessment of the physiologic changes in the postthrombotic syndrome.

To determine what physiologic changes might contribute to the development of the postthrombotic syndrome, venous outflow, venous refilling time, and valvular competence were assessed in 32 patients (39 limbs) with documented deep venous thrombosis. The follow-up ranged from nine to 144 months (mean, 41 months) after the acute deep venous thrombosis. Pain was noted by 49% of the patients, but more objective end points occurred less frequently (edema, 21%; pigmentation, 26%; ulceration, 3%). Venous outflow was lower in the affected limbs but was not a good indicator of those patients with or without symptoms. Venous refilling time after calf compression was markedly reduced in limbs with incompetent valves (mean +/- SD, 8.4 +/- 3.8 s v 25.3 +/- 12.1 s), as well as in those with edema, pigmentation, and ulceration. It appears that most of the sequelae of the postthrombotic syndrome can be attributed to the loss of valvular function.

Adult↗
PubMed1985

Stereospecific opiate binding in living human polymorphonuclear leucocytes.

Living human polymorphonuclear leucocytes were incubated with various opiate agonists and antagonists in radioreceptor assays. Binding of the opiate antagonists 3H-naloxone and 3H-diprenorphine and of the benzomorphan 3H-ethylketocyclazocine was found at 4 degrees C and at 37 degrees C, 3H-naloxone binding was stereospecific. Binding of the opiate agonist 3H-dihydromorphine was present at 37 degrees C but not at 4 degrees C and had a different time course as compared to the antagonists. At both temperatures no specific binding of the proteolytic stable analogue 3H-D-Ala-D-Leu-enkephalin was found. Autoradiography showed an unspecific accumulation of 3H-naloxone inside the cells and a specific localization of grains at the cell membrane.

Analgesics, Opioid↗
PubMed1985

Primary pediatric care. A comparison of use by adolescent and older mothers.

This survey compares the use of pediatric services during the first year of life by infants whose mothers were under 17 years of age with a random sample of babies born during the same period and at the same hospital but to older mothers. Both sets of mothers were found to have similar patterns of acute and well-child care. For adolescent mothers, use of a group practice emphasizing provider continuity significantly increased well-child visits and immunizations. The adolescent mother's late entry into prenatal care appeared to be related to a greater use of the emergency room and to inadequate well-child care. The existence of a sibling was related to inadequate well-child care for adolescents' babies but to improved levels of well-child care among older mothers' babies. These findings suggest that close monitoring of adolescent mothers with more than one child may improve the quality of medical care for their infants.

Adolescent↗
PubMed1985

Protection of indwelling vascular catheters: incidence of bacterial contamination and catheter-related sepsis.

We compared the incidence of catheter contamination and catheter-related sepsis in 200 noninfected patients admitted postoperatively to the surgical ICU. Four methods of catheter fixation were used: (a) povidone-iodine ointment (Betadine) with a sterile gauze and adhesive dressing (Elastoplast); (b) Op-Site film; (c) Op-Site spray followed by Op-Site film; and (d) Beta-dine and Op-Site film. Of 708 catheters used for 200 patients, 516 (72.8%) were cultured. There was no catheter-related septicemia but 13 (2.52%) catheters were contaminated. However, these were evenly distributed among the four groups. We, therefore, conclude that aseptic insertion of catheters, daily inspection of puncture site, and replacement of tubing are the determining factors in preventing catheter-related sepsis.

Bacterial Infections↗
PubMed1985

Cyclic Cushing's syndrome combined with cortisol suppressible, dexamethasone non-suppressible ACTH secretion: a new variant of Cushing's syndrome.

A 55 year old woman with an unusual form of Cushing's disease was studied. During several periods (periods lasting up to 84 days) evidence of cortisol hypersecretion with cycles occurring every 6 days was found. Suppression of plasma cortisol through orally administered dexamethasone (up to 32 mg per day) could not be achieved either during periods of cyclic cortisol hypersecretion or during apparent remission with normal cortisol secretion. Marked suppression of plasma ACTH was measured in response to an iv infusion of 50 mg cortisol over a period of 55 min whereas a similar test with 2 mg dexamethasone (iv bolus) did not suppress ACTH secretion. Transsphenoidal exploration of the sella revealed a tumour surrounding the anterior pituitary. Examination of the pituitary showed a few tiny tumour structures embedded in normal tissue which could not be removed, when the tumour was resected selectively under preservation of normal appearing tissue. Post-operatively, clinical and chemical remission (normal response to 1 mg dexamethasone) was observed for about 4 months. Thereafter, cortisol hypersecretion occurred again necessitating bilateral adrenalectomy. Our results are compatible with the assumption that normal hypothalamic-pituitary-adrenal suppressibility with cortisol, but not with dexamethasone, was caused by the loss of feedback receptors for dexamethasone in the presence of cortisol receptors in the cells which secrete ACTH or CRF. The combination of cyclic hypercortisolism with dexamethasone non-suppressible Cushing's syndrome has not been reported before and thus represents a new variant of Cushing's syndrome.

Adrenocorticotropic Hormone↗
PubMed1985

Uncrossed and crossed inhibition in the inferior colliculus of the cat: a combined 2-deoxyglucose and electrophysiological study.

The cat inferior colliculus (IC) was studied with 2-deoxyglucose (2-DG). By presenting high-frequency tone bursts to one ear and white noise bursts simultaneously to the other, a band of reduced or inhibitory labeling was revealed in the central nucleus (ICC) of the IC ipsilateral to the ear receiving the tone bursts. It was concluded that this ipsilateral inhibition might be related to the organization of excitatory/inhibitory units in ICC. In the opposite ICC, narrow bands of increased labeling were seen. In some animals, the positions of single units were marked, and tone frequencies were presented under 2-DG, which were the same as these units' characteristic frequencies (CFs). The positions of the units coincided with the position of the inhibitory bands, indicating that they were functional isofrequency-inhibitory contours. Unlike higher auditory centers, the binaural inhibitory areas were in register with and not orthogonal to the excitatory isofrequency contours. The inhibitory contours were generally larger than the excitatory contours and became even larger in more caudal sections. Both the inhibitory and excitatory contours extended into dorsal cortex areas of IC. In two other cats, high-frequency tone bursts and white noise bursts were presented to the same ear, and both a band of increased and a band of reduced labelling were found in the IC contralateral to this ear. The inhibitory band was always lateral to the excitatory band and was often smaller. They did not become larger in more caudal sections. The position of a unit in one cat was marked by pontamine sky blue, and the position of the unit coincided with the position of the excitatory band. It was concluded that this lateral inhibitory band represents high-frequency inhibitory sidebands of cells with CFs lower than the stimulating tone. It is concluded that the 2-DG method might reveal hitherto unknown inhibitory systems if stimuli could be combined with diffuse stimuli that raised the general background activity of sensory systems.

Acoustic Stimulation↗
PubMed1984

Control of peptide release from cells of the intermediate lobe of the rat pituitary.

When rats were injected with 6-hydroxydopamine the catecholaminergic nerve terminals in their intermediate lobes exhibited distinct signs of degeneration. Morphometric examination of the Golgi apparatus in cells of the intermediate lobe of these rats showed significant enlargement of Golgi cisternae. The release of adrenocorticotropin, beta-endorphin/lipotropin and alpha-melanotropin from intermediate-lobe cells in vitro was measured by radioimmunoassay. The high basal peptide release was inhibited by dopamine and stimulated by methyl-isobutyl-xanthine. In contrast, gamma-aminobutyric acid, serotonin, histamine and noradrenaline, or corticotropin-releasing hormone, rat hypothalamic extract and vasopressin had no or only very weak effects. These observations indicate that the synthetic apparatus of intermediate-lobe cells is constantly depressed by dopaminergic nerves. We were not able to stimulate peptide release from intermediate-lobe cells by use of the above-mentioned endogenous agents.

Adrenocorticotropic Hormone↗