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Biomedical subjects

R Martin

Publications and source records attributed to R Martin.

At least 631 records · Page 35Linked to original sources
PubMed1981

Enkephalin-related peptides: direct action on the octopus heart.

Immunocytochemical evidence for the occurrence of "vertebrate" peptides in the neuropil of the vena cava [12, 13] and the structural similarity between enkephalin precursor peptides and the molluscan cardioexcitatory peptide [16], lead us to study the action of enkephalin-related peptides on the octopus heart. Systemic hearts of Octopus vulgaris were perfused with sea wate and test substances and a crude extract of vena cave were added for 1 min; frequency and pressure were monitored continuously. The heptapeptide Leu5-enkephalin-Arg6-Phe7 and the Met5-analogue, both in the amidized form, displayed dose-response relationship with a sensitivity of about 10 nmol. The C-terminal tetrapeptide amides, Phe-Leu/Met-Arg-Phe-NH2, were active at the same doses. Opiate receptors do not seem to be involved in this action on the octopus heart, as naloxone treatment had no effect. Whereas the N-terminal portion of the heptapeptide is known to be crucial for activity as an opioid, the C-terminal NH2 group is essential for cardioexcitatory activity.

Animals↗
PubMed1981

Enkephalins co-exist with oxytocin and vasopressin in nerve terminals of rat neurohypophysis.

Evidence is accumulating that opiates inhibit the release of oxytocin and vasopressin by acting on nerve terminals in the neurohypophysis. Extracts of neurohypophysis have been shown to contain substantial amounts of Met- and Leu-enkephalin, and Leu-enkephalin-immunoreactive (IR) nerve fibres originating in the magnocellular hypothalamic nuclei have been described in the neural lobe, where the two hormones are secreted. We have compared the distribution of oxytocin, vasopressin and enkephalin immunoreactivity (IR) in the neurohypophysis of the rat, and report here that Met-enkephalin-IR is invariably associated with nerve terminals that contain oxytocin-IR whereas the terminals that contain vasopressin-IR often, but not invariably, are Leu-enkephalin immunoreactive.

Animals↗
PubMed1981

Estrogen receptor: a prognostic factor in breast cancer.

Two-hundred-seventeen women with primary breast carcinoma had an estrogen receptor determination tested by both the dextran-coated charcoal assay and sucrose density gradient. The results were correlated with the disease-free interval, survival, response to hormone therapy or chemotherapy, and site of recurrent disease. The disease-free interval (DFI) was significantly longer in premenopausal patients with estrogen receptor positive (ER+) determination compared with premenopausal patients with estrogen receptor negative (ER-) determinations, irrespective of nodal involvement (P less than 0.05). There was no difference between the postmenopausal patients. The survival of the ER+ patients was statistically longer than that of the ER- patients (P less than 0.05). Statistical significance remained when the patients were grouped according to menopausal status or nodal involvement (P less than 0.002 or less). Sixty-two patients were treated with hormonal therapy, either ablative or additive. Forty-eight percent of patients with ER+ responded compared with 6% of patients with ER- (P less than 0.0005). Seventy-nine patients received chemotherapy; 52% of the ER+ and 57% of the ER- patients responded (P less than 0.5). ER+ tumors had a predilection to metastasize in skin and bone, while ER- tumors metastasized more commonly to the viscera and brain.

Adenocarcinoma↗
PubMed1981

Comparison of the clinical effectiveness of lidocaine hydrocarbonate and lidocaine hydrochloride with and without epinephrine in epidural anaesthesia.

Epidural analgesia was administered to one hundred patients undergoing various types of surgical procedures. They were divided at random into four equal groups who received lidocaine hydrocarbonate or lidocaine hydrochloride, both with or without epinephrine. A double blind method was used. The study was designed first to test the validity of claims that lidocaine hydrocarbonate produces a shorter period of onset for effective analgesia, a more profound sensory and motor block, and a higher spread of analgesia than the hydrochloride salt and secondly, to identify the respective roles of carbon dioxide and epinephrine in obtaining this alleged superior effectiveness. The results of the study showed that carbon dioxide improved the quality of sensory block, but we could not find any significant difference between lidocaine hydrocarbonate and lidocaine hydrochloride salt, with and without epinephrine, with regard to rapidity of onset, upward spread of analgesia and quality of motor block. As was already known, duration of analgesia was prolonged by the addition of epinephrine but not by the addition of carbon dioxide. They study also showed that the compliance of the epidural space was decreased in the lidocaine hydrocarbonate groups compared to those with lidocaine hydrochloride. There is a positive correlation between the duration of sensory block or the upper level of analgesia and compliance in the hundred patients studied. It is concluded that the hydrocarbonate base, because of its more profound sensory block in the L5-S1 segment, can be useful for operations on the lower extremities, especially in the L5-S1 segmental distribution. However, knowing that the hydrocarbonate base is more expensive, one must use his own judgment in appraising the cost-benefit of its use.

Adult↗
PubMed1981

Effects of carbon dioxide and epinephrine on serum levels of lidocaine after epidural anaesthesia.

Carbonated lidocaine is believed to penetrate membranes more rapidly than its hydrochloride salt and could possibly cause higher serum levels. To compare serum levels, arterial blood samples drawn at intervals were analyzed in a group of 18 patients under epidural anaesthesia with equivalent doses of lidocaine hydrochloride and lidocaine hydrocarbonate, with and without epinephrine. Results show that serum levels were significantly higher when lidocaine hydrocarbonate was used for epidural analgesia.

Anesthesia, Epidural↗
PubMed1981

Prescription-writing by pediatric house officers.

Prescription-writing is an important aspect of medical practice. Illegible and/or incorrect prescriptions can result in loss of patient, physician, and pharmacist time and may cause therapeutic errors or drug toxicity. An examination to evaluate prescription-writing was administered to a group of pediatric house officers and faculty. Follow-up monitoring of actual prescriptions written in the pediatric clinic was performed. Deficient prescription-writing techniques and weakness in the therapeutic knowledge of beginning pediatric interns were identified. The data indicate that proper prescription-writing (especially the use of controlled substances) should be taught to house officers and that the therapeutic knowledge of beginning pediatric interns cannot be assumed to be adequate.

Arizona↗
PubMed1981

Myocardial necrosis and ventricular aneurysm following closed chest injury in a child.

A 4-year-old child is described who suffered an unsuspected myocardial contusion which led to the formation of a ventricular aneurysm 2 months after an automobile accident. Electrocardiography, thallium scanning, myocardial enzyme assays, two-dimensional echocardiography and, when indicated, cardiac catheterization, may aid in the early diagnosis of cardiac contusions. In the patient presented, resection of the aneurysm 6 months postinjury was followed by elimination of almost all the mitral regurgitation originally present and good cardiovascular function.

Accidents, Traffic↗
PubMed1981

Immunocytochemical demonstration of catechol methyltransferase in Candida tropicalis.

Catechol methyltransferase (S-adenosyl-L-methionine : catechol O-methyltransferase; EC 2.1.1.6) was localized immunocytochemically in the yeast Candida tropicalis by the unlabelled antibody enzyme method, involving soluble peroxidase-antiperoxidase complex. Immunoreactivity was detected by light and electron microscopy in the outer layer of the cell wall and at the plasma membrane. The possible function of the methyltransferase in C. tropicalis id discussed.

Candida↗
PubMed1981

Comparative studies of two systems of prophylactic antibiotics in head and neck surgery.

One hundred and seventeen patients undergoing operations on the head and neck were investigated for the causes of infection. There was a close relationship between the pre-operative culture and the risk of infection. There was a greater risk of infection (10.7%) when the pharynx was opened than when it was not (0.0%). The operations most liable to infection are laryngopharyngectomy and those in which skin flaps are used. The isolation of pathogenic bacteria in the operative exudate did not in general predispose to the development of infection, which did not occur when these cultures were negative. Positive cultures obtained from the drain on 3 consecutive days were a significant indication that infection will probably occur.

Anti-Bacterial Agents↗
PubMed1981

Brain stem sites mediating specific and non-specific temperature effects on thermoregulation in the pekin duck.

1. Thermodes were chronically implanted into various levels of the brain stem of sixteen Pekin ducks. The effects of local thermal stimulation on metabolic heat production, core temperature, peripheral skin temperature and respiratory frequency were investigated. 2. Four areas of thermode positions were determined according to the responses observed and were histologically identified at the end of the investigation. 3. Thermal stimulation of the lower mid-brain/upper pontine brain stem (Pos. III) elicited an increase in metabolic heat production, cutaneous vasoconstriction and rises in core temperature in response to cooling at thermoneutral and cold ambient conditions and, further, inhibition of panting by cooling and activation of panting by heating at warm ambient conditions. The metabolic response to cooling this brain stem section amounted to -0.1 W/kg. degrees C as compared with -7 W/kg. degrees C in response to total body cooling. 4. Cooling of the anterior and middle hypothalamus (Pos. II) caused vasodilatation in the skin and did not elicit shivering. The resulting drop in core temperature at a given degree of cooling was greater than the rise in core temperature in response to equivalent cooling of the lower mid-brain/upper pontine brain stem. 5. Cooling of the preoptic forebrain (Pos. I) and of the myelencephalon (Pos. IV) did not elicit thermoregulatory reactions. 6. It is concluded that the duck's brain stem contains thermoreceptive structures in the lower mid-brain/upper pontine section. However, the brain stem as a whole appears to contribute little to cold defence during general hypothermia because of the inhibitory effects originating in the anterior and middle hypothalamus. Cold defence in the duck, which is comparable in strength to that in mammals, has to rely on extracerebral thermosensory structures.

Animals↗
PubMed1981

Characterization of some groups of gram-negative nonfermentative bacteria by the carbon source alkalinization technique.

A total of 541 gram-negative nonfermentative bacterial strains comprising 26 species and unclassified groups were characterized by routine diagnostic and carbon substrate alkalinization techniques. These microorganisms were tested for the ability to cause alkalinization of a basal medium on a total of 217 substrates. We found that 58 carbon substrates had some discriminatory potential. We also performed 30 routine diagnostic tests. The results of these studies were evaluated by numerical taxonomy techniques. A cluster analysis of the results by the Jaccard coefficient method identified 30 clusters at the 45% level. We identified 39 tests that separated most of the groups. Groups of similar organisms or organisms that were difficult to identify were analyzed, and tests that were differential were identified. Because of variability within the clusters, further studies utilizing deoxyribonucleic acid-deoxyribonucleic acid homologies should be undertaken.

Bacteria↗
PubMed1981

[Gene expression, metabolic regulation and aging].

The biological ageing comprises changes of of structure and function depending on time with the beginning of the autonomy of a living being up to death. On the one hand, the causes of this process are genetically fixed, on the other hand they depend on environmental factors and are not programmed. In the course of life the total genome and also the nucleic acid underlie influences, which must have consequences on the gene expression. In these cases the changed sensitivity of the genetic apparatus in comparison to hormones is impressionably changed. The decreased protein biosynthesis may be stimulated by increased amino acid concentrations and by SH-substances, Age-depending changes are also observed for enzymatically catalyzed reactions and in the regulation of chains of metabolism. At first the biologic ageing appears as a complex multiform process, which reaches the simplest integration level in the cellular metabolism.

ATP Citrate (pro-S)-Lyase↗
PubMed1981

Researches on Pseudophyllidea (Carus, 1813) in the south of Chile. IV Occurrence of Diphyllobothrium dendriticum (Nitzch).

Experimental infections were established with Diphyllobothrium sp. plerocercoids obtained from Salmo gairdneri, a fish introduced at the beginning of the 1900s in the lake region of Chile. These permitted us to obtain adult parasites in Larus dominicanus and Canis familiaris. The histological features of the plerocercoids, their relation to the host, adult pattern and susceptibility of hosts allowed us to determine the presence of Diphyllobothrium dendriticum (Nitzch) for the first time in South America in the lacustrine region of southern Chile. It is believed that this cestode was introduced to this ecosystem by infected persons travelling from North America of Europe or, alternatively, brought by migratory birds, e.g., Sterna hirundo, S. paradisea or Larus pipixcan on their winter visits to South America.

Animals↗