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Biomedical subjects

R David

Publications and source records attributed to R David.

At least 73 records · Page 4Linked to original sources
PubMed1990

Platelet aggregating IgG antibody to platelet surface glycoproteins associated with thrombosis and thrombocytopenia.

Previously described platelet-aggregating antibodies associated with thrombosis and thrombocytopenia required heparin for their in vivo and in vitro expression. We have observed a patient with thrombosis who became thrombocytopenic during heparin treatment, but who suffered further thrombotic events and continued thrombocytopenia for 3 months after heparin withdrawal. The patient's plasma contained a potent platelet aggregating factor reactive with both his own and normal platelets in the absence of heparin. It also caused [14C]serotonin secretion from labelled platelets from normal donors and patients with either Glanzmann's thrombasthenia or Bernard-Soulier syndrome. This factor was an IgG and was neutralized by antibody specific for IgG lambda light chains. While the patient was thrombocytopenic an IgG paraprotein with lambda light chains was detected by isoelectrofocussing. After corticosteroid treatment it disappeared and the patient recovered. The active, but not the recovery serum contained IgG which immunoprecipitated a glycoprotein with characteristics of Glycoprotein IV from platelets labelled with Na[3H]BH4/periodate. Thus platelet-aggregating IgG antibodies with direct specificity for platelet surface glycoproteins may be associated with thrombosis/thrombocytopenia.

Humans↗
PubMed1990

Persistently raised intraocular pressure following extracapsular cataract extraction.

In this population based study we have reviewed the files of all patients who underwent an extracapsular cataract extraction (ECCE) between 1984 and 1987, were normotensives prior to surgery, and were followed up for at least 10 months after the ECCE. From a total of 1047 operations 746 qualified for the inclusion criteria; of these, 16 (2.1%) were found to have a consistently raised intraocular pressure (greater than 21 mmHg) on more than two occasions) at four months or later after surgery and throughout at least a six-month period. An increased incidence of secondary aphakic glaucoma was associated with anterior chamber IOL implantation (p less than 0.001) and posterior capsule rupture (p less than 0.01), but not with any of the other variables examined (age, sex, surgeon).

Adult↗
PubMed1990

Available FSH receptors in adult rat testis in vivo.

It has been suggested that the tight junctions formed between Sertoli cells during the peripubertal period constitute a barrier to circulating FSH in the adult testis, limiting its access to the lumen of the seminiferous tubules. There are also reports of FSH receptor-binding inhibitors. These observations prompted us to study the extent of FSH receptor availability in vivo in the adult rat. Experimental rats were given an intracardiac injection of rat FSH (rFSH), and the occupied receptor was measured by radioimmunoassay of acid-released rFSH from the testis. In the saline-injected control animals, there were 247 fmol occupied FSH receptors/g testis, and as much as 1788 fmol of the unoccupied high-affinity receptors/g testis, as measured by in-vitro binding studies. After intracardiac injection of increasing amounts of rFSH (up to 606 pmol), receptor occupancy increased to a maximum plateau of only 448 fmol/g testis. In contrast, when rFSH was given by intratesticular injection in order to achieve pharmacological doses in the testis, the maximum binding was 662 fmol/g testis. Scatchard analysis of the in-vivo data revealed, however, that the maximum concentration of the high-affinity receptor was 452 fmol/g testis, a value concordant with the highest in-vivo binding observed in animals given intracardiac rFSH (448 fmol/g). A single injection of the hormone did not induce down-regulation of FSH receptors, regardless of the dose, whereas multiple injections of menotrophin were effective, at least to some extent. Despite the receptor loss, the immediate receptor availability was maintained, suggesting the presence of a receptor pool.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Congenital insensitivity to pain with neuroparalytic keratitis.

Congenital insensitivity to pain is a well-defined entity in the group of sensory deficiency syndromes. To the best of our knowledge, unilateral neuroparalytic keratitis associated with congenital insensitivity to pain has not been reported. We report such a case to alert clinicians to this potentially blinding problem.

Child, Preschool↗
PubMed1989

Differing susceptibilities of platelets from normal individuals and patients with von Willebrand's disease to attack by quinine- and quinidine-dependent antiplatelet antibodies.

Reactivity of quinine- and quinidine-dependent antiplatelet antibodies has been compared in platelet-rich-plasma (PRP) from normal donors and from patients with von Willebrand's disease (vWd). One quinine-dependent antibody (Q.Ab) caused platelet aggregation and [14C] serotonin release with only 7 of 12 normal donors, while another Q.Ab and a quinidine-dependent antibody (Qd.Ab) caused aggregation and release with all 12. Drug-dependent IgG binding and PF 3 availability induced by the antibodies were, however, comparable in all donors. Differences in responsiveness were associated with platelets and not plasma. vWd platelets showed normal drug-dependent IgG binding, but decreased aggregation and serotonin release to most drug-dependent antibodies. Responsiveness was not restored by purified vWf:Ag, but, in one case, was corrected by normal plasma or cryoprecipitate. Drug-dependent binding of the Q.Ab which caused variable responsiveness in normals was to the same platelet antigens (GPIb and GPIIIa) in both normal and vWd platelets and did not require plasma components. Reduced PF 3 availability was seen with some antibodies in some vWd patients. Plasma from two of these patients inhibited aggregation of normal platelets to Q.Ab and one of these inhibited aggregation to ADP. Antiplatelet antibodies were detected in these two plasmas by ELISA. Thus some Q.Ab produce different responses with platelets from different donors. In vWd, reduced responsiveness to Q.Ab and Qd.Ab may result from production of inhibitory antiplatelet antibodies.

Autoantibodies↗
PubMed1989

Circumferential perirenal urinoma mimicking nephromegaly on urography.

Four cases of circumferential perirenal urinoma in patients with cancer are described. Intravenous urography showed evidence of apparent renal enlargement. In 1 case, opacification of extravasated urine was dense enough to be seen on the urogram, and the diagnosis was confirmed by computed tomography (CT). In the other cases, sonography followed by CT diagnosed urinoma, after tumor invasion had been suggested because of the pseudonephromegaly. Ureteral obstruction was demonstrated in all cases, due to retroperitoneal adenopathy in 1 case and to pelvic tumor in the other 3. Sonography or CT is required for the diagnosis of circumferential perirenal urinoma mimicking nephromegaly urographically.

Adult↗
PubMed1989

Plasmodium falciparum: DNA probe diagnosis of malaria in Kenya.

We previously reported isolation of DNA probe which specifically recognizes Plasmodium falciparum and developed a simple method for its use. The sensitivity and specificity of this DNA probe method have now been extensively field tested in comparison with those of conventional microscopic examination of blood films in two separate studies in Malindi, Kenya, involving a total of 1179 patients. In the second study, which used improved techniques, sensitivity of the DNA probe was 89% when compared to microscopy. We conclude that the DNA probe method compares favorably with conventional microscopy in detecting parasite densities as low as 25 parasites per microliter of blood. A significant advantage of the DNA probe method is that it utilizes a standardized procedure which can simultaneously and reproducibly analyze a large number of samples without opportunity for significant reader bias.

Adult↗
PubMed1989

Myofibroblasts in peripheral giant cell granuloma. Light and electron microscopic study.

Myofibroblasts are found in various pathologic conditions including lesions containing giant cells, such as central giant cell granuloma and the giant cell tumor of tendon sheath (nodular tendosynovitis). In the present study, myofibroblasts were found in peripheral giant cell granuloma (PGCG) using the TP-Levanol fast cyanine 5RN histochemical procedure and electron microscopy. A number of myofibroblasts displayed intracellular collagen fibrils. The presence of myofibroblasts supports the reactive nature of PGCG.

Fibroblasts↗
PubMed1989

The clavicle: normal and abnormal.

The clavicle is an unusual long bone with many unique embryologic features. It is often involved in congenital and acquired disorders. Traumatic, inflammatory, neoplastic, metabolic and many other miscellaneous lesions may also affect the bone. Because of its ligamentous attachments and the presence of articulations at both ends, the clavicle can also be involved in arthritic diseases. This article illustrates the radiographic manifestations of many of the disorders of the clavicle that are commonly encountered in clinical practice.

Bone Diseases↗
PubMed1989

The many faces of neuroblastoma.

Neuroblastoma is a common tumor in childhood. It arises in the adrenal gland or in various extraadrenal primary sites of the sympathetic chain. Clinically, it may present as an abdominal mass or as disseminated metastatic disease. We studied 52 patients with neuroblastoma, and the typical and unusual radiographic features of the disease are presented.

Adrenal Gland Neoplasms↗
PubMed1989

Bladder diseases and imaging methods.

New and exciting diagnostic modalities which substantially change the evaluation of the urinary bladder have become available in the last decade. This is a review of the principles involved in and the advantages of diagnostic imaging using the modalities available to study the urinary bladder in a modern radiologic facility. It emphasizes the values of the different modalities in specific disease states. Excretory urography, cystography, and voiding cystourethrography were the mainstay of the evaluation of bladder pathology. These modalities are still good screening methods under certain circumstances but are relatively limited in comprehensive assessment of the bladder. Bladder studies using radionuclides, such as nuclear cystography, still have a space in the long-term follow-up of pediatric patients due to their relative low radiation dose. Since the addition of ultrasonography, computed tomography, and more recently, magnetic resonance imaging to the radiologist's armamentarium of imaging modalities, there has been a tremendous improvement not only in the demonstration of bladder abnormalities, but also in the staging of bladder neoplasms. The relative merits of these past and present imaging modalities are illustrated. Their appropriate contributions to improved quality of care of patients with bladder disease are also discussed.

Humans↗
PubMed1989

Acromegaly in an infant.

Serial hormonal studies were carried out in a girl with a growth hormone-secreting pituitary adenoma and hyperprolactinemia diagnosed at 21 months of age, the youngest verified case of acromegaly. The child had progressive macrocephaly, noted at 6 months of age, which preceded the rapid acceleration of linear growth by nearly 1 year. At 21 months of age, the girl's head circumference measured 55 cm (+5.5 SD) and her height was 97.6 cm (+4.4 SD). Preoperative serum growth hormone level was 135 ng/mL, somatomedin C was 1,540 ng/mL (normal for bone age 18 to 97 ng/mL), and prolactin was 370 ng/mL (normal less than 20 ng/mL). Following total resection of a large adenoma, immunohistochemical staining of the tumor showed growth hormone but not prolactin. With longitudinal monitoring of the child for 2 years postoperatively, persistently low growth hormone levels were demonstrated and normal growth velocity (6 cm/yr). Peak serum growth hormone levels ranged from 2.8 to 4.1 ng/mL after stimulation tests with insulin, arginine, and L-dopa. Maximum sleep-entrained growth hormone level was 3.4 ng/mL. At the same time, serum somatomedin C levels measured serially were normal (29 to 111 ng/mL), whereas simultaneous prolactin levels were moderately increased (30 to 147 ng/mL). The data support the hypothesis that hyperprolactinemia may have contributed to stimulating somatomedin C and sustaining the normal growth rate in this child.

Acromegaly↗