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Biomedical subjects

D Martin

Publications and source records attributed to D Martin.

At least 739 records · Page 41Linked to original sources
PubMed1983

Relation of nephron recruitment to detectable filtration and recovery of function after release of ureteral obstruction.

In this study, the role of nephron recruitment to measurable filtration in the recovery of whole kidney GFR following release of ureteral obstruction of 18 hr duration was characterized in the young rat with a modification of Hanssen's technique. Following release of bilateral (BUO) or unilateral (UUO) ureteral obstruction, the expected increases in fractional sodium and water excretion were observed and remained constant throughout the interval of the study (approximately 3 hr). However, the GFR of the postrelease kidney of rats subjected to BUO and UUO increased significantly within this time frame. Surprisingly, the percent increase in GFR was greater in the the UUO group. In both groups, there was a positive correlation between the number of filtering nephrons and time after release. The increase in the number of filtering juxtamedullary and superficial nephrons detectable with this technique was symmetrical after release of UUO and BUO. However, at all intervals of study, there were significantly fewer filtering nephrons in the postrelease kidney of the UUO and the BUO group. These studies indicate that the mechanism of recovery of GFR in the postrelease kidney in the two settings of ureteral obstruction is quite different.

Animals↗
PubMed1983

The effects of oxygen radicals on pulmonary edema formation.

This article is a review of the current literature concerning the possible involvement of oxygen radicals in the development of pulmonary edema. The article focuses on changes in capillary endothelium caused by many different imposed experimental conditions that may be related to the generation of O2, OH. or H2O2. Data from our laboratory show that scavengers such as superoxide dismutase, dimethylsulfoxide, and catalase as well as leukocyte depletion provide partial protection to the very caustic alpha-naphthylthiourea. The literature concerning the possible involvement of leukocyte or tissue generation of oxygen radicals in the various forms of pulmonary edema is combined into a simple model that may explain why pathologic tissues show variable responses to compounds that should either scavenge the oxygen radicals or prevent leukocyte involvement.

Capillary Permeability↗
PubMed1983

Experimental pancreatitis does not produce pulmonary hypertension.

The onset of experimental hemorrhagic pancreatitis in dogs was rapidly followed by a deterioration of CO, blood pressure, LVSW and RVSW, along with significant elevations of Hct, SVR and PVR. These alterations could all be reversed by the administration of Ringer's lactate. These findings support the concept that the major physiopathologic characteristic of severe acute pancreatitis is a loss of effective plasma and extracellular fluid volumes and that the replacement of fluid losses corrects the hemodynamic alterations. In neither of the experimental groups did pulmonary hypertension develop. We found no evidence in this model of hemorrhagic pancreatitis for a circulating pulmonary vasoactive substance.

Acute Disease↗
PubMed1983

Syncope in the elderly: a pragmatic approach.

Carotid massage should be performed in elderly patients only if other diagnostic studies have not been helpful, since in rare instances, transient and permanent neurologic deficits have been precipitated by this maneuver. Patients with auscultatory findings of cardiovascular disease should certainly undergo further evaluation with appropriate studies such as echocardiography, stress testing, or cardiac catheterization.

Aged↗
PubMed1983

Deep nephron and collecting duct function after unilateral reduction in renal mass.

Papillary micropuncture was used to study juxtamedullary nephron and terminal collecting duct function in the remnant kidney when the contralateral kidney was present. Urine osmolality from the remnant kidney was significantly lower than that measured for the control kidney. Surface nephron function appeared unaffected by remnant formation. Delivery of water to the bend of the loop of Henle of deep nephrons was increased. It is proposed that part of this increase in delivery is a consequence of a decrease in water extraction along the descending limb of the loop of Henle. Surprisingly, there was a decrease in fractional sodium delivery to the bend of the loop of Henle. This suggests enhanced fluid reabsorption in the proximal segments of deep nephrons. Water and sodium reabsorption along the terminal segment of the collecting duct was not affected by remnant formation. However, fluid osmolality measured along this segment was lower than that obtained in controls. Values obtained along the descending limb of the loop of Henle of deep nephrons did not differ from collecting duct fluid. This suggests no significant alteration in collecting duct permeability. Rather, the findings of the present study suggest that the lower osmolality of the final urine may be due, in part, to a reduction in the deposition of sodium in the papillary interstitium.

Absorption↗
PubMed1982

Streptococcal wound infections caused by a vaginal carrier.

During a four-month period, ten cases of group A streptococcal (GAS) postoperative wound infection occurred among patients in a community hospital. Bacteremia developed in two patients, and one patient died. Group A streptococcal surgical wound infections were associated with exposure to a circulating nurse and duration of surgery. Prophylactic antibiotic reduced the risk of infection. Vaginal, perineal, and anal cultures from nurse A yielded GAS, serotype M-4, T-4, as did the blood of two infected patients. Penicillin eradicated GAS colonization of nurse A, and she returned to work. Five months later, two additional cases of GAS postoperative wound infections occurred and were associated with recolonization of the same nurse with GAS, serotype M-nontypeable, T-12. She was relieved of patient-care duties, and no further cases have occurred.

Anal Canal↗
PubMed1982

Cholera on the Texas Gulf Coast.

Cholera is being increasingly recognized in the Gulf Coast region. This report describes two cholera cases of classic clinical presentation. Both cases were caused by toxigenic Vibrio cholerae, one of an 01 serotype and one of a non-01 serotype. Vibrio cholerae was also isolated from the home environments of both patients. These findings indicate that cholera continues to be detected on the Gulf Coast, that non-01 V cholerae infections may be clinically indistinguishable from V cholerae 01 infections, and that both 01 and non-01 V cholerae strains are capable of survival in Gulf Coast environments.

Adolescent↗
PubMed1982

Identification of T cell in parapsoriasis infiltrates. Use of an anti-human T-cell serum and the immunoperoxidase technique.

"Parapsoriasis" is a term used to include a heterogeneous group of conditions, one variant of which, at least, eventuates in mycosis fungoides in a substantial percentage of cases. The T-cell origin of mycosis fungoides is well established. The lack of similar information on lymphoid cell types in parapsoriasis prompted an immunoperoxidase study using a specific antihuman T-cell serum in a group of seven patients with parapsoriasis. Our findings demonstrated a preponderantly T-cell infiltrate in the categories of parapsoriasis examined.

Adult↗
PubMed1982

Histamine-induced inhibition of lymphocyte proliferation and lysosomal enzyme release from polymorphs may not be mediated via H1- or H2-receptors.

Histamine, selective histamine H1- and H2-receptor agonists, and chemical analogues of these compounds lacking activity at histamine receptors, were tested as inhibitors of phytohaemagglutinin-induced human lymphocyte proliferation and zymosan-induced release of lysosomal enzymes from human polymorphs. No correlation was found between their inhibitory potency in these systems and their relative activity at histamine H1- or H2-receptors.

Dimaprit↗
PubMed1982

Hyperkeratinization and hyperplasia of the forestomach epithelium in vitamin A deficient rats.

Specific pathogen free F-344 rats were kept on a vitamin A deficient diet for 3-5 months. After 3 months on this diet the forestomach epithelium showed a mild atrophy. Stereological cytology showed a marked increase in the volume density of cytoplasmic filament bundles and decrease in the volume density of non-bundled cytoplasmic filaments. The volume fraction of keratohyalin granules increased whereas the volume fraction of membrane coating granules decreased. Some animals maintained for 4-5 months on the hypovitaminic diet exhibited the same mild atrophic forestomach epithelium accompanied by hyperkeratinization. Others showed a marked epithelial atrophy and 4 out of 12 animals revealed a marked hyperplasia with increased 3H thymidine labeling index and several papillomatous proliferations. Although many of these alterations reflect a decrease in proliferation as well as hyperkeratinization, the latter changes were not unlike those produced by known carcinogens, and support the putative important role of vitamin A in both carcinogenesis and chemoprevention.

Animals↗
PubMed1982

The relationship of weight loss to surface roughness of composite resins from simulated toothbrushing.

This study was designed to measure percentage of weight loss during simulated toothbrushing of five different composite resins. The surface roughness of each composite resin was also measured after each year of simulated toothbrushing for a period of 5 years. The following conclusions were reached: 1. Despite the loss of toothbrush efficiency, all composite resins tested tended to have a decreasing wear rate with the increasing time of toothbrushing. 2. Profile (with a soft filler) and Isopast (with a microsized filler) showed the greatest resistance to abrasion and retained the smoothest surface. 3. Prestige, which demonstrated the greatest percent weight loss, also has a soft barium filler. Loss of the filler as an alkaline reaction in water due to soluble barium compounds may cause the binder to release filler particles prematurely.

Acrylic Resins↗
PubMed1982

Hypercalcemia associated with parenteral amino acid and dextrose infusion.

A patient receiving parenteral nutrition with an amino acid dextrose solution developed hypercalcemia which seemed related to the rate of nutrient infusion. In a retrospective study of patients receiving parenteral nutrition over a 3-month period six of 72 (8%) developed hypercalcemia. After changes in infusion rate there were corresponding changes in the serum calcium concentration. There was a significant correlation between the serum calcium concentration and the average infusion rate over the preceding four days (p = 0.012). This was even more significant (p less than 0.005) when ionized calcium was calculated to diminish the effects of calcium binding by proteins.

Adolescent↗
PubMed1982

Antimanic, antidepressant, and antipanic effects of opiates: clinical, neuroanatomical, and biochemical evidence.

These clinical data may offer some support for the hypothesis that opiates have antidepressant, antimanic, and antipanic effects. This hypothesis should be studied directly by double-blind studies of the effects of exogenous and synthetic endogenous opioid peptides in patients with major depressive illness, panic and anxiety states, schizophrenia, and schizo-affective illness. These clinical data support our studies in nonhuman primates and man which suggest a common LC or NE hyperactivity may underly both drug withdrawal and spontaneous panic states. Whether endorphin deficiency or derangements account for the postulated NE hyperactivity needs additional study and we will discuss our preliminary work later. Failure of endorphins to terminate bursts in LC firing rate and NE release may be responsible for both of these types of panic states. In addicts, this mechanism could exist prior to opiate use, or abuse of potent exogenous endorphinomentic compound may cause an endorphin-abnormality. Both of these possibilities would be compensated by continuous opiate maintenance. Methadone maintenance is a complicated psychiatric, psychological, and social phenomenon. Further studies are necessary to evaluate the role of opiate maintenance in treating or suppressing the emergence of underlying psychopathology. Previous psychiatric hospitalization or treatment for a schizophrenic or affective illness may contraindicate absolutely the use of clonidine or other rapid detoxification methods. These data suggest the possibility of substituting a nonaddicting psychotropic medication for opiates in some patients who are self-medicators. The clinical data support other data suggesting the potential antipsychotic, antidepressant, and antianxiety/antipanic effects of the endogenous opioids, endorphins, and exogenous opioids, endorphins, and exogenous opiates. These and other data suggest potential utility for opioid agonists and endorphin testing in psychiatric treatment and diagnosis.

Adult↗
PubMed1982

Increased pulmonary microvasuclar permeability induced by alpha-naphthylthiourea.

The effects of alpha-naphthylthiourea (ANTU) on lung microvascular permeability to plasma proteins were studied in anesthetized open-chest dogs. Lymph flow (Jv) was recorded, and total protein in plasma and lymph was analyzed after cannulating a small prenodal lung lymphatic. The protocol involved four experimental periods. Period 1. During this base-line period the preparation stabilized and steady states were reached in Jv, lymph total protein, pulmonary arterial pressure (Ppa), and left atrial pressure (Pla). Period 2. Pla was increased to approximately 20 cmH2O and maintained at that level until Jv and protein measurements attained a new steady state. Period 3. After Pla was lowered to control levels, ANTU (5 mg/kg body wt) was infused intravenously and parameters were measured for 3 h. Period 4 Pla was again raised to the pre-ANTU levels of period 2 and maintained for an additional 2-3 h. The lymphatic total protein clearance increased 8.6-fold for an equivalent increase in pulmonary capillary pressure after ANTU. Vascular permeability was assessed by estimating the osmotic reflection coefficient (sigma d) for total protein at the pulmonary capillary membrane. Sigma d decreased from 0.65 to 0.40 following ANTU. From plasma protein fractions in four experiments, equivalent pore radii for the capillary membrane of 95 and 280 A were calculated after ANTU compared with 80 and 200 A for normal lung capillaries. In addition, extravascular lung water increased from 3.8 +/- 0.16 to 5.87 +/- 0.25 following ANTU and to 7.55 +/- 0.55 (g/g blood-free dry wt) when Pla was elevated with ANTU. The experimental design allowed quantitative assessment of the vascular permeability increase after ANTU by use of lymph protein fluxes that had minimal errors due to changes in surface area or lymph contamination from nonpulmonary structures.

Animals↗
PubMed1982

Ammonium handling by superficial and juxtamedullary nephrons in the rat. Evidence for an ammonia shunt between the loop of Henle and the collecting duct.

Papillary and surface micropuncture was used to assess the effects of a chronic metabolic acidosis on the renal tubular handling of ammonium by surface nephrons, juxtamedullary nephrons, and the terminal segment of collecting duct. Rats chronically fed ammonium chloride had an expected decline in arterial pH and bicarbonate concentration associated with a doubling in the amount of ammonium excreted and a decline in urine pH. The glomerular filtration rate and absolute delivery of water and sodium to micropuncture sites of surface and deep nephrons was not measurably altered. Ammonium delivery to the end of the proximal tubule increased from 853+/-102% to 1,197+/-142% (SE) of the filtered load of ammonium after the induction of metabolic acidosis. This increase was due to a rise in tubular fluid ammonium content from 2.31+/-0.23 to 4.06+/-0.28 mM/liter. After the induction of acidosis, absolute and fractional delivery of ammonium ion to the end of the distal tubule was less than to the end of the accessible portion of the proximal tubule. These findings indicate that ammonium is lost in the intervening segment.Ammonium handling by deep nephrons was profoundly affected by acid loading. Absolute delivery to the bend of the loop of Henle increased twofold while fractional delivery rose from 1,222+/-108% to 1,780+/-132% of the filtered ammonium. This was due to a marked increase in ammonia entry. During acidosis, ammonium delivery to the terminal segment of the collecting duct was doubled (709+/-137% in controls vs. 1,415+/-150% in acidosis, P < 0.005) but did not change between proximal and tip collecting duct sites. In both groups of animals delivery of ammonium to the terminal segment of the collecting duct was greater than to end distal tubular micropuncture sites suggesting that ammonia entry occurred between these two sites. The differences in delivery was greater after the induction of a metabolic acidosis (887+/-140% vs. 384+/-144%, P < 0.05). Thus, the present study indicates that deep nephrons contribute to the adaptive increase in ammonium excretion seen during the induction of metabolic acidosis. The data also suggest that ammonia leaves the nephrons at a site(s) along the loop of Henle to enter the collecting duct and that the induction of a metabolic acidosis enhances this reentry.

Acidosis, Renal Tubular↗