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Biomedical subjects

M McCormack

Publications and source records attributed to M McCormack.

At least 37 records · Page 2Linked to original sources
PubMed1993

Leak point of incontinence: a measure of the interaction between outlet resistance and bladder capacity.

A total of 48 consecutive spina bifida patients undergoing routine urodynamic studies was classified into 2 groups depending upon whether they demonstrated uninhibited bladder contractions. Of the patients 34 demonstrated detrusor hyperreflexia and 14 had detrusor areflexia. These 2 groups were then subdivided depending on the continence status. Of the areflexic and hyperreflexic groups, 6 and 7 patients, respectively, were wet despite at least 2 years of conservative medical management. Leak point pressure and leak point volume were determined in all patients and results were compared in both subgroups. In the hyperreflexic groups leak point volume but not leak point pressure was significantly different between the wet and dry patients. The areflexic group demonstrated the opposite finding, that is the leak point pressure but not the leak point volume was significantly different between wet and dry patients. From these studies we determined that in the areflexic group leak point pressure was useful to predict incontinence, whereas in the hyperreflexic group leak point volume was more useful. The addition of the measurement of leak point pressure and leak point volume during routine urodynamic studies in myelodysplastic patients enhances accurate diagnosis and may select those who will best benefit from bladder augmentation and/or a procedure to increase outlet resistance.

Adolescent↗
PubMed1993

"No stent, no diversion" Mathieu hypospadias repair.

The Mathieu procedure is a surgical technique for anterior hypospadias repair. The disadvantage of this technique is the prolonged hospital stay associated with postoperative urinary diversion. In an effort to reduce the length of hospital stay the authors carried out a prospective study to determine the usefulness of urethral stents and urinary diversion after Mathieu repair. Seventeen boys (mean age 4.1 years) formed the experimental group, and 19 boys (mean age 4.6 years) served as controls. Urinary diversion and urethral stents were used postoperatively in the control group but not in the experimental group. After a minimum of 6 months of observation the complications noted in both groups were found to be similar. The authors conclude that urinary diversion and urethral stents have no beneficial effects on surgical outcome but do prolong hospital stay.

Child, Preschool↗
PubMed1993

The role of sigmoidoscopy in the management of gunshot wounds to the buttocks.

The charts of all patients (n = 70) admitted over 26 months after sustaining a gunshot wound to the buttocks were reviewed to assess the role of physical examination, routine radiologic studies, and sigmoidoscopy in the evaluation of these patients. There were 68 men and 2 women. Sixteen patients underwent sigmoidoscopy, which demonstrated a rectal injury in 7. Six of these patients had other abnormalities on either physical examination or plain pelvic radiographs that would have otherwise led to operation. There were no missed injuries and no morbidity in the remaining patients that were managed without sigmoidoscopy. Indications for sigmoidoscopy were gross blood on rectal examination in 2, bullet path with proximity to the rectum in 13, and persistent abdominal pain in 1. All patients with gross blood on rectal examination (n = 5) and blood at the urethral meatus (n = 2) had visceral injuries. One patient underwent celiotomy for an injury at 15 cm that was noted on sigmoidoscopy performed because the bullet trajectory was in proximity to the rectum. Sigmoidoscopy can be performed selectively in patients sustaining a gunshot wound to the buttocks when the proximity of the wound to the rectum is in doubt.

Abdomen↗
PubMed1992

Multiple trkA proteins in PC12 cells bind NGF with a slow association rate.

Rat pheochromocytoma (PC12) cells express two distinct nerve growth factor receptors (NGFRs), p75NGFR and trkA (p140trk). In addition to these receptors, by using 125I-mNGF affinity labeling and BS3 chemical cross-linking of PC12 cell protein, we have identified two additional trkA protein bands with apparent molecular weights of 220,000 and 300,000. These bands contain trkA, but were not immunoprecipitated by p75NGFR-specific antisera, suggesting that they do not represent trkA/p75NGFR protein complexes. The 220-kDa trkA band apparently represents trkA with alternate post-translational modification. The appearance of the 300-kDa trkA band was dependent on cross-linker concentration and could be diminished in the presence of reducing agents, suggesting that it represents a trkA dimer. All trkA bands were phosphorylated on tyrosine residues when bound to mNGF, suggesting that they participate in NGF-induced signal transduction. NGF binding kinetics to all three trkA bands were indistinguishable, with slow dissociation rates, and a slow association rate that required approximately 1 h to reach equilibrium levels at 4 degrees C. All three trkA bands bound the related neurotrophin brain-derived neurotrophic factor and neurotrophin-3 with a profile characteristic of trkA.

Animals↗
PubMed1992

Agreement between clinical methods of measurement of urinary frequency and functional bladder capacity.

We assessed the agreement between 2 methods of data gathering of particular interest in urology: patient questionnaire and examination vs. frequency-volume charts. One hundred consecutive patients consulting our out-patient clinic were chosen for this study; 88 completed the study. Urinary frequency and bladder capacity were evaluated in each patient by using the above methods. The agreement between different methods of measurement was assessed by determining whether the 2 methods were interchangeable, a condition occurring if results of both methods fall within predetermined limits of variability. The results showed poor agreement between subjectively estimated urinary frequency and chart-determined urinary frequency. Moreover, different methods of measuring bladder capacity (endoscopic vs. chart) gave different results. Since chart-determined data are probably a more valid indication of urinary habits, we suggest that frequency-volume charts should be used more often in the investigation and follow-up of patients with micturition disorders.

Circadian Rhythm↗
PubMed1992

Mechanism of impaired energy metabolism during acidosis: role of oxidative metabolism.

Isolated perfused rat hearts were used to study the effects of metabolic acidosis on energy metabolism. Hearts perfused with different substrates (glucose, pyruvate, and succinate) were subjected to metabolic acidosis. With all substrates, there were comparable decrements in oxygen consumption (approximately 35%), cardiac function (decrease in first derivative of pressure of 65%), and similar changes in high-energy phosphates (approximately 150% increases in inorganic phosphate and 25% decreases in phosphocreatine concentrations) with metabolic acidosis. To further investigate the metabolic effects of acidosis, isolated cardiac mitochondria were exposed to different incubation media pH conditions and given simple metabolites (glutamate/malate, succinate, or pyruvate) or fatty acids (octanoate). Reduction of incubation media pH to 6.0 did not significantly affect either coupled respiration rate or the respiratory control ratio (RCR) with any substrate. These data suggest that metabolic acidosis induces decreases in energy production in the isolated perfused heart by inhibiting mitochondrial substrate utilization and not by impairing glycolysis. However, this impairment of mitochondrial function is not a direct effect of acidosis itself but appears to occur secondarily to some other effects of acidosis which are, as yet, incompletely understood.

Acidosis↗
PubMed1991

The urine specific gravity dipstick: a useful tool to increase fluid intake in stone forming patients.

High fluid intake is the only preventive dietary measure that can be recommended to all patients with stones. However, the efficacy of dietary advice given to patients is unknown. We compared the impact of dietary advice to increase hydration (group 1, 57 patients) and of no dietary advice (group 2, 83 patients) on 24-hour urine volume. No significant difference was noted between groups 1 (1,624 ml.) and 2 (1,732 ml.). We then determined if urine specific gravity dipsticks could help patients increase the 24-hour urine volume. A correlation between 24-hour urine volume and mean urine specific gravity was performed on 263 randomly chosen patients. There was an inverse relationship between urine specific gravity and 24-hour urine volume with a correlation coefficient of 0.522 (y = 1.0207 - 0.00374x). Most patients (81.6%) with 24-hour urine volumes of less than 2.1 had a urine specific gravity of more than 1.010. The use of specific gravity dipsticks was evaluated as a tool to help 24 patients increase the 24-hour urine volume. The 24-hour urine volume increased significantly (p less than 0.05, paired Student's t test) in patients after feedback from specific gravity dipsticks when they were instructed to keep the urine specific gravity at or less than 1.010 (average 24-hour urine volume increased 192%). We conclude that dietary advice may be insufficient to modify fluid intake habits in stone patients. However, modifications of fluid intake habits may be improved by feedback from specific gravity dipsticks.

Adolescent↗
PubMed1991

An initial assessment of the cost and utilization of the Integrated Academic Information System (IAIMS) at Columbia Presbyterian Medical Center.

The concept of "one stop information shopping" is becoming a reality at Columbia Presbyterian Medical Center (CPMC). The goal of our effort is to provide access to university and hospital administrative systems as well as clinical and library applications from a single workstation, which also provides utility functions such as word processing and mail. Since June 1987, CPMC has invested the equivalent of $23 million dollars to install a digital communications network that encompasses 18 buildings at seven geographically separate sites and to develop clinical and library applications that are integrated with the existing hospital and university administrative and research computing facilities. During June 1991, 2425 different individuals used the clinical information system, 425 different individuals used the library applications, and 900 different individuals used the hospital administrative applications via network access. If we were to freeze the system in its current state, amortize the development and network installation costs, and add projected maintenance costs for the clinical and library applications, our integrated information system would cost $2.8 million on an annual basis. This cost is 0.3% of the medical center's annual budget. These expenditures could be justified by very small improvements in time savings for personnel and/or decreased length of hospital stay and/or more efficient use of resources. In addition to the direct benefits which we detail, a major benefit is the ease with which additional computer-based applications can be added incrementally at an extremely modest cost.

Academic Medical Centers↗
PubMed1990

Chronic anaemia, hyperbaric oxygen and tumour radiosensitivity.

Anaemia is an important factor in the response of some human tumours to radiotherapy. The outcome is also influenced by whether the treatment is given in air or high pressure oxygen (HPO). The present study examined the relationship between anaemia and tumour response to radiation given in air or HPO in C3H mice transplanted with a mammary adenocarcinoma using a growth delay assay to assess the radiation response. Chronic anaemia was induced by the use of a low iron diet and was characterized by a significant reduction in host haematocrit and whole blood viscosity. In addition, anaemia was associated with a right shift in the oxyhaemoglobin dissociation curve and an increase in the volume doubling time of the tumour; but there was no change in the concentration of 2,3-diphosphoglycerate in the red cells. Radiation studies with these anaemic mice demonstrated that the tumour radiosensitivity was decreased when treatment was given in air. HPO was successful in overcoming the increased radioresistance associated with anaemia. This result suggested that tumours grown in anaemic mice have a higher hypoxic fraction than those grown in control mice. Changes in host physiology with chronic anaemia may contribute to the benefit seen with HPO but such alterations per se may be inadequate to maintain tumour oxygenation when treatment is given in air.

Adaptation, Physiological↗
PubMed1988

Physiologic consequences and complications of vasectomy.

Sterilization of men and women is the most popular method of contraception in Canada. The contraceptive effect of a vasectomy usually occurs within 3 months. The production of sperm, however, is not interrupted, and an increase in pressure proximal to the ligation site may cause rupture of the epididymis or the ductus deferens, with extravasation of spermatozoa and the formation of granulomas or sperm antibodies. Increased pressure may also explain the postvasectomy pain syndrome.

Autoantibodies↗
PubMed1987

Effect of liver fatty acid binding protein on fatty acid movement between liposomes and rat liver microsomes.

Although movement of fatty acids between bilayers can occur spontaneously, it has been postulated that intracellular movement is facilitated by a class of proteins named fatty acid binding proteins (FABP). In this study we have incorporated long chain fatty acids into multilamellar liposomes made of phosphatidylcholine, incubated them with rat liver microsomes containing an active acyl-CoA synthetase, and measured formation of acyl-CoA in the absence or presence of FABP purified from rat liver. FABP increased about 2-fold the accumulation of acyl-CoA when liposomes were the fatty acid donor. Using fatty acid incorporated into liposomes made either of egg yolk lecithin or of dipalmitoylphosphatidylcholine, it was found that the temperature dependence of acyl-CoA accumulation in the presence of FABP correlated with both the physical state of phospholipid molecules in the liposomes and the binding of fatty acid to FABP, suggesting that fatty acid must first desorb from the liposomes before FABP can have an effect. An FABP-fatty acid complex incubated with microsomes, in the absence of liposomes, resulted in greater acyl-CoA formation than when liposomes were present, suggesting that desorption of fatty acid from the membrane is rate-limiting in the accumulation of acyl-CoA by this system. Finally, an equilibrium dialysis cell separating liposomes from microsomes on opposite sides of a Nuclepore filter was used to show that liver FABP was required for the movement and activation of fatty acid between the compartments. These studies show that liver FABP interacts with fatty acid that desorbs from phospholipid bilayers, and promotes movement to a membrane-bound enzyme, suggesting that FABP may act intracellularly by increasing net desorption of fatty acid from cell membranes.

Acyl Coenzyme A↗
PubMed1987

SV40 small t antigen enhances the transformation activity of limiting concentrations of SV40 large T antigen.

A murine recombinant Neo(r) retrovirus encoding the SV40 small t antigen was used to infect Balb/c 3T3 CIA31 cells. From analyses of G418-resistant clones containing at least as much intact t as Cos-1 cells, we found that t, alone, had no detectable A31 transforming activity. In contrast, we noted that SV40 large T promoted A31 agar colony formation when present over a 5- to 7.5-fold concentration range. However, at the low end of the spectrum, its transforming effect was manifest inefficiently except in the presence of t. Thus a major role for t in the SV40 transforming mechanism is to enhance directly or indirectly the transforming function of T.

Animals↗
PubMed1986

A recombinant murine retrovirus for simian virus 40 large T cDNA transforms mouse fibroblasts to anchorage-independent growth.

A recombinant murine retrovirus containing the intact cDNA sequence for the simian virus 40 (SV40) large T antigen (T) was constructed by using the pZIPNeo SV(X)1 vector. Psi 2 packaging cells were then transfected, and G418-resistant clones were used to generate helper-free viral stocks. NIH 3T3 mouse fibroblasts infected by the recombinant T cDNA retrovirus were selected fro G418 resistance. Such cultures synthesized authentic SV40 T and were transformed to anchorage-independent growth at high efficiency. Therefore, this vector has allowed the study of the transformation properties of T under conditions of neutral drug selection and in the absence of SV40 small t antigen.

Animals↗