Search PubMed⌕ Search

Biomedical subjects

D Martin

Publications and source records attributed to D Martin.

At least 721 records · Page 40Linked to original sources
PubMed1985

Cognitive development and aspects of adolescent sexuality.

Difficulty with adjustment to sexuality by adolescents has been of increasing concern to both educators and human service professionals in recent years. The cognitive development and behavior of adolescents as it pertains to sexuality and the implications for helping them overcome maladaptive sexual behavior is discussed.

Adolescent↗
PubMed1984

Juvenile laryngeal papillomatosis with pulmonary spread. Regression following transfer factor therapy.

A 6-year-old girl with a history of juvenile laryngeal papillomatosis since 6 months of age and progressing pulmonary extension of the tumor for two years was treated with transfer factor prepared from her mother. Within one month of the onset of therapy, she exhibited marked clinical improvement. A computed tomographic scan performed after four months of therapy revealed almost complete resolution of her pulmonary lesions.

Child↗
PubMed1984

Elevated red blood cell/plasma choline ratio in dementia of the Alzheimer type: clinical and polysomnographic correlates.

In a prospective study we have observed a shift in distribution of red blood cell (RBC)/plasma choline ratios among patients with probable dementia of the Alzheimer type (DAT), compared with healthy controls and depressed patients. Fifteen of 22 DAT patients (68%) showed RBC/plasma choline ratios greater than 1.9, in contrast to 9 of 26 healthy controls (35%) and 7 of 20 depressives (35%). These significant differences confirm and expand earlier observations. The subgroup of DAT patients with elevated RBC/plasma choline ratios is older and more cognitively impaired, shows later onset of dementia, and has less rapid eye movement (REM) sleep than the DAT subgroup with normal RBC/plasma choline ratios. Within the entire group of DAT patients, moreover, the RBC/plasma choline ratio shows a significant inverse correlation with REM sleep latency. These findings are discussed in relation to abnormalities in other nonneural Alzheimer tissues and within the context of cholinergic involvement in both DAT and the timing of REM sleep.

Aged↗
PubMed1984

Circadian temperature variation in healthy aged and in Alzheimer's disease.

Circadian temperature variation was monitored in healthy older adults and in health-, age-, and sex-matched Alzheimer's dementia patients. Oral and rectal temperatures were analyzed for mean level, amplitude, and phase using cosinor analyses. Mean 24-hour temperature level was not altered by dementia. A significant sex effect, however, was observed among dementia patients with women exceeding men in mean 24-hour temperatures and across daytime time periods. Cosinor-derived phase and amplitude measures were unaffected by dementia or by sex. This indicates that the primary neuronal degeneration characteristic of Alzheimer's disease in its early stages does not disable the neural pathway(s) controlling circadian temperature regulation. Some impairment in temperature homeostatic regulation may be present, however, because a greater intrasubject temperature variability was observed in Alzheimer men than in control men.

Age Factors↗
PubMed1984

Massive mediastinal hematoma caused by a double-lumen subclavian catheter.

Double-lumen subclavian catheters have recently been released for use as a temporary blood access for extracorporeal circulation. Initial reports indicate that once properly inserted, these catheters are safe. However, massive mediastinal hematoma that occurred 3 days after insertion and uneventful initial dialysis with a double-lumen subclavian catheter has been documented. The patient experienced excruciating pain immediately after the onset of the subsequent dialysis and was found to have developed a massive mediastinal hematoma. It appears that at some point after the completion of the initial dialysis, the catheter tip eroded the vein and entered the mediastinum. As a result, the proximal (arterial) perforations were inside the vein, allowing blood to freely enter the circuit and be forcefully pumped into the mediastinum through the distal (venous) perforations near the tip. Prompt recognition of the problem and immediate discontinuation of dialysis prevented a potential fatal outcome in this case.

Adult↗
PubMed1984

High-frequency ventilation: lymph flow, lymph protein flux, and lung water.

The effects of high-frequency oscillatory (HFV) ventilation on lung fluid balance and microvascular permeability to macromolecules were measured in open-chest dog lungs. Prenodal lung lymph flow, concentration of total plasma proteins in lymph and plasma, pulmonary arterial and left atrial pressure, cardiac output, and blood-free lung wet-to-dry weight ratios were measured for conventional mechanical ventilation (CMV, 12/min, 200-300 ml tidal volume) and HFV of 15 Hz and a stroke volume of 40-50 ml for normal and elevated left atrial pressures. HFV increased both lymph flow and lung water (68 and 20%, respectively), and lymph-to-plasma ratios of total plasma proteins remained unchanged. When left atrial pressure was increased, an analysis of lymph protein flux indicates that the lung microvascular permeability was not altered by HFV. The increase in lymph flow and lung water associated with HFV may reflect an increased microvascular exchange surface area or a change in interstitial fluid pressure.

Animals↗
PubMed1984

Elimination of plasmidic resistance to ampicillin and of enterotoxinogenicity in certain enteric gram-negative bacteria after incubation with high concentrations of amprolium.

We have observed that treatment with high concentrations of a thiamine analog (amprolium) can lead to the elimination of the plasmidic resistance to ampicillin and the production of enterotoxin in wild Escherichia coli strains and in E coli and Salmonella typhimurium strains which had received the pKM101 plasmid through bacterial conjugation. By computer analysis, we also have determined that there is a highly significant (P less than 0.01) synergism between ampicillin and amprolium which reduces considerably the growth of certain enteric bacterial strains which have a plasmidic resistance to ampicillin and which were not markedly affected by amprolium alone, in our experimental conditions. Our data indicate that the rate of loss of the plasmid pKM101 after treatment of R+ bacterial strains with amprolium can be increased.

Ampicillin↗
PubMed1984

Pulmonary pathology in renal transplant recipients.

Studies of the lungs have revealed multiple functional and histopathological abnormalities in patients with chronic renal failure, but data following renal transplantation are extremely limited. We examined postmortem data from 20 transplant patients and found pulmonary abnormalities in most patients. The number of pulmonary abnormalities noted in patients with poor transplantation, averaged 5.3 per patient. The corresponding number was significantly less (3.4 per patient) in the group with good transplant renal function, surviving more than one year after transplantation. Pulmonary calcification, fibrosis, and hemosiderosis were found in several patients in the former group but in none of the latter group. This observation suggests reversibility of these pulmonary abnormalities with successful renal transplantation.

Adult↗
PubMed1983

A role for an indoleamine other than 5-hydroxytryptamine in the hypothalamic thermoregulatory pathways of the rat.

1. Intrahypothalamic injection of either 5-hydroxytryptamine (5-HT) (20 mug) or tryptamine (1 mug) caused hypothermia and hyperthermia respectively in lightly restrained rats maintained at an ambient temperature of 20 +/- 1 degrees C.2. Both the 5-HT- and the tryptamine-sensitive sites were located within the same region of the preoptic area.3. When rats were tested at different ambient temperatures (4, 20 and 29 degrees C), intrahypothalamic injection of 5-HT caused a marked fall in core temperature (-1.3 degrees C) in rats maintained at 4 degrees C, but smaller responses were obtained at 20 and 29 degrees C (-0.9 and -0.5 degrees C respectively). Tryptamine caused a significant hyperthermia in rats kept at 20 degrees C, but had no significant effect in rats maintained at either 4 or 29 degrees C.4. The hypothermic effect of 5-HT was selectively antagonized by systemic pre-treatment with cyproheptadine (2.5 mg/kg), but not by methergoline (0.625 mg/kg) and methysergide (0.2 mg/kg). In contrast, the hyperthermic effect of tryptamine was blocked by methergoline and methysergide, but not by cyproheptadine.5. Cyproheptadine (2.5 mg/kg) reduced the ability of rats to cope with a heat load but had no effect on the response to cold. In contrast, methergoline (0.625 mg/kg) and methysergide (0.2 mg/kg) reduced the ability to cope with cold but the rats' ability to cope with a heat load remained intact.6. These results suggest the existence of two indoleamine pathways within the preoptic anterior hypothalamus involved in the control of body temperature: a serotonergic pathway mediating heat loss and a non-serotonergic pathway mediating heat gain. The non-serotonergic system may exert its effects by modulating the activity of a central serotonergic system.

Animals↗
PubMed1983

Segmental analysis of the renal tubule in buffer production and net acid formation.

Papillary and surface micropuncture in Munich-Wistar rats was used to assess the role of proximal segments of superficial and juxtamedullary (JM) nephrons, the distal tubule of superficial nephrons, and the terminal collecting duct in acid excretion. The relative role of these segments in ammonium production, bicarbonate reclamation, and net acid formation was assessed under hydropenic conditions and after a chronic acid load. In these two settings the proximal segment of both kinds of nephrons is the major site of ammonium production and bicarbonate reclamation. However, this segment's contribution to net acid formation was only significant during acidosis. On the other hand, segments beyond the distal tubule appear to be the major site of acid formation. In situ pH measurements were lower in these nephron segments and fell even more after the induction of an acidosis. Ammonia appears to enter fluid between the end of the distal tubule and the base of the collecting duct. In vivo pH measurements made near the bend of Henle's loop of JM nephrons were more alkaline than near the end of the proximal tubule of superficial nephrons. It is postulated that this difference in pH allows ammonium to dissociate, permitting the movement of ammonia out of the tubule lumen and into collecting duct fluid where it is protonated and, therefore, reentrapped. This process is enhanced by the ingestion of a chronic acid load.

Acidosis↗
PubMed1983

Handling of ammonium by the renal proximal tubule during acute metabolic acidosis.

The present studies were designed to assess the handling of ammonium (NH+4) by the proximal tubule during acute metabolic acidosis (AMA). After tubule fluid collections were obtained with micropuncture techniques and in situ pH was determined near the end of the proximal tubule, 0.2 N HCl was infused intravenously at 17 microliter X min-1 X 100 g body wt-1. Thirty to sixty minutes later, samples were obtained and pH measurements were made near the previous micropuncture sites. During AMA, urine pH fell and total acid excretion doubled due to an increase in NH+4 excretion from 581 +/- 63 to 1,153 +/- 61 nmol X min-1 X g kidney wt-1 (P less than 0.001). Acid excretion did not change in time controls. Tubule fluid NH+4 rose from 2.17 +/- 0.15 to 3.45 +/- 0.24 mM during acid infusion (P less than 0.001) and its delivery to the end of the proximal tubule nearly doubled (67.8 +/- 6.3 vs. 33.9 +/- 2.9 pmol X min X g kidney wt-1 before acid infusion, P less than 0.001). This increase in delivery during AMA was due to enhanced ammonia (NH3) entry into the proximal tubule. In situ pH determined near the end of the proximal tubule averaged 6.94 +/- 0.04 before acid infusion and did not change afterwards (6.87 +/- 0.05). These data are consistent with the hypothesis that in AMA the increase in NH+4 excretion is due primarily to an increase in the cortical production of NH3.

Acidosis, Renal Tubular↗
PubMed1983

Effect of reduced renal mass on ammonium handling and net acid formation by the superficial and juxtamedullary nephron of the rat. Evidence for impaired reentrapment rather than decreased production of ammonium in the acidosis of uremia.

Papillary and surface micropuncture were used to study the handling of ammonium and the formation of net acid by surface nephrons, deep nephrons, and the terminal segment of collecting duct (CD) after renal mass was reduced by two-thirds. Net acid excretion by the remnant kidney (RK) was significantly reduced, averaging 794+/-81 neq/min (SE) compared with 1,220+/-105 neq/min after sham operation (P < 0.001), due to a decrease in ammonium excretion (494+/-54 vs. 871+/-79 nmol/min in controls, P < 0.001). Urinary pH and titratable acid excretion were not different in the two groups of animals. After RK formation, ammonium delivery to the end of the proximal tubule increased nearly threefold and averaged 66.2+/-5.6 compared with 18.4+/-2.9 pmol/min in controls, (P < 0.001). This greater delivery of ammonium was primarily due to renal tubule entry rather than to changes in the filtered load and was only partially related to the differences in flow rate. Ammonium processing by deep nephrons was profoundly affected by a reduction in renal mass. Although absolute delivery of ammonium was greater to the bend of Henle's loop (BHL), the difference could be accounted for on the basis of an increase in nephron size. Thus, fractional delivery (FD(NH+4)) to this site was not different for the two groups of animals, averaging 1,567+/-180% in controls and 1,400+/-181% in the group with the RK. Hydrogen secretion in the proximal segments of deep and surface nephrons did not increase in proportion to the decrease in renal mass and as a consequence bicarbonate delivery to the end of the proximal tubule of surface nephrons and to the BHL of deep nephrons was increased. When renal mass was reduced FD(NH+4) to the base of the terminal CD doubled but did not change by the tip. In both groups FD(NH+4) to the base of the CD was greater than to the end of the distal tubule. However, the increase was the same. On the other hand, the increase in the net acid index between the end of the distal tubule and the base of the CD was profoundly greater in rats with an RK. This difference was primarily due to bicarbonate reabsorption rather than enhanced ammonium reentry. Indeed, >400% of the fractional ammonium delivered to the end of the proximal tubule was lost from the tubule fluid. The data suggest that the decrease in acid excretion by the RK is due to two factors. First, hydrogen secretion in the proximal segments of both nephron populations fails to increase in the proportion to the reduction in renal mass. Second, a reduced reentrapment of ammonia, rather than its impaired production, causes ammonium excretion to decrease.

Acidosis↗