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Biomedical subjects

P Friedman

Publications and source records attributed to P Friedman.

At least 55 records · Page 3Linked to original sources
PubMed1990

Molecular defect (Gla+14----Lys) and its functional consequences in a hereditary factor X deficiency (factor X "Vorarlberg").

Factor X (FX) "Vorarlberg" is a congenital FX deficiency characterized clinically by a mild bleeding tendency. Homozygous individuals have a FX activity of less than 10% in the extrinsic system and 25% in the intrinsic system. FX antigen is 20%. Using molecular techniques, two point mutations were detected in the coding sequence of the FX Vorarlberg gene: a G----A at base pair 160 in exon II resulting in a change of Gla14 (GAA) to Lys (AAA); a G----A at base pair 424 in exon V resulting in a change from Glu102 (GAG) to Lys (AAG). The mutations abolished a TaqI restriction site in exon II and an MnlI site in exon V. To determine whether these mutations are present on one or on both alleles, restriction analyses of amplified exon II and exon V fragments were performed. Analysis of the pedigree showed that the genotype for the mutation on exon II (homozygous versus heterozygous) correlates with the severity of the phenotypic coagulation defect. We therefore conclude that the mutation in exon II is responsible for the functional defect in FX Vorarlberg. We have also purified the mutant FX protein from patient plasma. Purified FX Vorarlberg is indistinguishable from normal FX on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its activity is 15% of normal FX upon activation with factor VIIa/tissue factor, 75% upon activation with factor IXa/factor VIIIa, and 100% upon activation with RVV. Activation at varying Ca2+ concentrations shows that the affinity of FX Vorarlberg for Ca2+ is decreased. Factor Xa Vorarlberg is able to convert prothrombin at a normal rate but also shows decreased affinity for Ca2+ in this interaction. Upon addition of Ca2+, FX Vorarlberg does not undergo the same conformational change as normal FX. Our data show that FX Vorarlberg has a decreased affinity for Ca2+ which impedes a normal conformational change. This leads to a decreased rate of activation by factor VIIa/tissue factor and by factor IXa. The decrease is much more marked for the extrinsic than for the intrinsic pathway.

Amino Acid Sequence↗
PubMed1987

Malignant external otitis versus acute external otitis.

Malignant External Otitis (MEO) and Acute External Otitis (AEO) are clinically very similar in their beginnings. It is important to differentiate between them very early. Bone scanning is the best diagnostic tool. Eight cases of AEO and MEO are herewith presented.

Acute Disease↗
PubMed1987

The diagnostic criteria of malignant external otitis.

The diagnostic criteria of malignant external otitis (MEO) have been reviewed. They were divided into two categories: obligatory and occasional. The obligatory criteria are: pain, edema, exudate, granulations, microabscess (when operated), positive bone scan or failure of local treatment often more than 1 week, and possibly pseudomonas in culture. The occasional criteria are diabetes, cranial nerve involvement, positive radiograph, debilitating condition and old age. All of the obligatory criteria must be present in order to establish the diagnosis. The presence of occasional criteria alone does not establish it. The importance of Tc99 scan in detecting osteomyelitis is stressed. When bone scan is not available, a trial of 1-3 weeks of local treatment is suggested. Failure to respond to such treatment may assist in making the diagnosis of MEO.

Diagnosis, Differential↗
PubMed1985

Percutaneous transluminal coronary angioplasty with an over-the-wire system.

The original Gruentzig coaxial catheter system for percutaneous transluminal coronary angioplasty (PTCA) utilized a blunt, closed-end, inner balloon catheter with a short guide wire attached to its tip. Options for safely crossing severe stenoses with this large, nonmaneuverable catheter were limited. More recently, over-the-wire systems have been developed in which the lesion initially is crossed with a small-caliber floppy or steerable guide wire, then by the balloon catheter advanced over the wire. Technical success was achieved in 78 of our first 100 PTCAs with this system. Significant cardiac complications occurred in ten patients, seven of whom required emergency coronary bypass surgery. A recently published survey of all PTCA techniques reported a technical success rate of 62%. Our higher success rate may be attributed to certain advantages of the over-the-wire system, which are discussed in detail. A learning curve is associated with this procedure: our success rate was 65% in the first 20 cases but 81% thereafter. These results can be considered typical of those expected at hospitals now beginning PTCA programs with advanced over-the-wire technology.

Angioplasty, Balloon↗
PubMed1985

Partial cauda equina compromise: result of sacral stenosis.

Although partial or complete cauda equina compromise due to lumbar stenosis is a recognized entity, cauda equina compromise due to sacral stenosis is extremely uncommon. We present a patient with a three-week history of right thigh and buttock pain who developed right scrotal and buttock numbness, urinary retention, and difficulty with bowel evacuation. The patient had diminished sensation to right buttock and anus pinprick with decreased anal sphincter tone and absent bulbocavernosus reflex. Lumbosacral spine films revealed only minimal degenerative changes, while lumbar myelogram showed L4-L5 and L5-S1 ventral extradural defects. Only a drop of pantopaque descended caudally below the level of the L5-S1 interspace. Operatively, significant stenosis and thickening of the posterior sacrum with compromise of the lower sacral nerve roots was noted. Bilateral sacral laminectomy was performed and the symptoms resolved postoperatively. This case illustrates an unusual clinical entity: partial cauda equina compromise due to sacral stenosis.

Adult↗
PubMed1983

Lumboatrial shunt: case report.

Hydrocephalus without ventriculomegaly and pseudotumor cerebri may present special problems in its treatment. Lumboperitoneal shunting, although frequently effective, is not successful in all cases. A lumbar subarachnoid to venous shunt is described as an alternative to lumboperitoneal shunting. A case illustrating its use is reported.

Adult↗
PubMed1982

Cerebral vasospasm and intraluminal filling defects.

Angiographically demonstrated arterial luminal narrowing after operations for intracranial aneurysms is a well-documented phenomenon. However, the mechanisms responsible for neurological dysfunction in the presence of vasospasm have not been clearly defined. Destructive changes have been demonstrated within the walls of vasospastic vessels. These changes consist of desquamation of endothelium and thrombus formation, necrosis of smooth muscle cells, and repair by connective tissue proliferation. A 50-year-old man with two aneurysms on the right carotid artery postoperatively developed ischemic symptoms and on angiography was shown to have multiple intraluminal filling defects and vasospasm. Ephemeral intraluminal thrombus is postulated as the inciting cause of morbidity in cerebral vasospasm in some cases.

Carotid Artery Diseases↗
PubMed1981

Release of PGE and PGI2 in the pump-perfused dog kidney and associated hypotension.

The mechanism of enhanced renal prostaglandin (PG) release in the in situ pump-perfused kidney was studied in anesthetized dogs. Pump perfusion caused a gradual decrease in mean arterial blood pressure (BP) from 163 to 128 mmHg over an 80-min period. The renal arteriovenous level of PGE and plasma renin activity (PRA) were increased by a mean of 1.36 ng/ml and 22 ng AI.ml-1.h-1, respectively. In a second group of dogs treated with captopril, pump perfusion did not alter PGE or BP, but increased PRA. When the animals were treated with indomethacin, the renal arteriovenous levels of PGE and 6-keto-PGF1 alpha were not changed but PRA increased during the 80 min of pump perfusion. In a fourth group of dogs that had undergone renal denervation and phentolamine treatment, changes in PGE and BP occurred during pump perfusion similar to the changes in the control group, and 6-keto-PGF1 alpha release by the kidney also increased. The results indicate that renal PG release during group perfusion is mainly due to the activation of the renin-angiotensin system and that the hypotension due to pump perfusion is PG mediated.

6-Ketoprostaglandin F1 alpha↗
PubMed1981

Pharmacological evaluation in conscious dogs of factors involved in the renal vasodilator effect of captopril.

The objective of this study was to examine the roles of the blockade of formation of angiotensin II and prostaglandins in the renal vasodilator effect of captopril in conscious salt-replete dogs. Blood pressure was recorded from an indwelling catheter and renal blood flow (RBF) was measured with an electromagnetic flowmeter and an implanted flow probe. Plasma renin activity was measured by radioimmunoassay. The effect of captopril (0.2 mg/kg i.v.) on RBF was compared in dogs given either saralasin (0.5 micrograms/kg min i.a.) or indomethacin (5mg/kg i.v.) with that in dogs given saline vehicle. Control plasma renin activity in these groups of animals before drug treatment ranged from 0.74 to 1.18 ng of angiotensin 1 per ml/hr. Captopril decreased blood pressure from 102 +/- 4 to 92 +/- 4 mm Hg (P less than .01) and increased RBF from 278 +/- 23 to 345 +/- 29 ml/min (25%) (P less than .01) in saline vehicle-treated animals. In the presence of intrarenal infusion of saralasin, captopril did not increase RBF but decreased blood pressure slightly. Captopril still increased RBF by 18% in indomethacin-treated dogs. These results suggest that the renal vasodilator effect of captopril in conscious salt-replete dogs is mainly due to the blockade of angiotensin II formation. Furthermore, the renin-angiotensin system appears to have an influence on renal vascular tone even under these basal conditions.

Angiotensin I↗
PubMed1981

Delayed complication of Matson operation for hydrocephalus: case report.

A 26-year-old woman had had a lumbar subarachnoid-ureteral shunt established at the age of 10 weeks for hydrocephalus. She developed normally and had no trouble until meningitis developed because of reflux from a urinary tract infection. The meningitis responded to antibiotic treatment, and the shunt was removed from the subarachnoid space. Subsequently, the patient deteriorated clinically, with ictal episodes of altered consciousness, headache, and signs of midbrain dysfunction. Despite normal size ventricles on serial computed tomographic scans, her intracranial pressure was markedly elevated, which was shown by spinal puncture pressure. A diversionary lumboperitoneal shunt was inserted. An immediate, sustained recovery followed. The recognition of increased intracranial pressure in the absence of ventriculomegaly led to management that averted a disastrous outcome.

Adult↗
PubMed1980

Relationship of reinforcement by student clinicians and peers to accuracy of imitated grammatical constructions during language training.

Percentages of correctly imitated grammatical constructions were examined within a framework of reinforcement theory. Four small treatment groups, each of 4 language-delayed children, were repeatedly observed interacting with different student-clinicians. The Therapy Reinforcement Schedule was used to obtain frequency counts of verbal and non-verbal reinforcements so that within each language group the students could be objectively divided into those who frequently and infrequently were reinforcing, and the children into those for whom peer-reinforcement was high or low. The resulting 4 groups were compared for proportions of accurately imitated constructions with a repeated-measures analysis of variance design (student-clinicians' reinforcement x peers' reinforcement x trials). Correctly scored imitations increased significantly over trials. In addition, children interacting with frequently reinforcing students received higher imitation scores than those with infrequently rewarding ones. Significant main effects of reinforcement by the peer group were not observed, although a reliable interaction of student-clinicians' reinforcement x peers' reinforcement was present. Regression analyses indicated the importance of certain types of reinforcements in predicting accuracy of imitation.

Child, Preschool↗