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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

Treatment of elevated intraocular pressure with concurrent levobunolol and pilocarpine.

Between July 1983 and January 1986, 54 patients with open-angle glaucoma or ocular hypertension were treated for 3 months with 2% pilocarpine hydrochloride (given four times daily) and one of two beta-adrenoceptor blocking drugs, levobunolol hydrochloride (0.5% [17 patients] or 1% [19 patients]) or 0.5% timolol maleate (18 patients), given twice daily. Before entry into the study all patients had had stable intraocular pressure (IOP) with treatment with 0.5% timolol and 2% pilocarpine. Stable IOP was successfully maintained in up to 88% of the patients in the two levobunolol-pilocarpine groups and in 83% of those in the timolol-pilocarpine group. Two patients experienced adverse reactions: one, who received timolol and pilocarpine, suffered blepharoconjunctivitis, and the other, who received 1% levobunolol and pilocarpine, experienced bradycardia. The results indicate that the levobunolol-pilocarpine regimens were as safe and effective as the timolol-pilocarpine regimen in stabilizing IOP.

Adrenergic beta-Antagonists

Osteomyelitis, acute and chronic.

In certain patient populations, osteomyelitis is a significant clinical problem. The judicious use of plain film radiographs and radionuclide bone imaging by the imaging consultant has a critical role in the early detection and diagnosis of osteomyelitis. This complementary imaging approach produces the highest and greatest accuracy in the documentation of skeletal infections. Inadvertent delay in the initiation of appropriate therapy can be obviated utilizing these imaging techniques and undue morbidity averted.

Acute Disease

Juvenile autoimmune thyroiditis. Hormonal status at presentation and after long-term follow-up.

Thirty children and adolescents with the clinical diagnosis of juvenile autoimmune thyroiditis (JAT) were studied. Twenty-six patients were female and four were male. The median age at diagnosis was 12.9 years (range, 7.5 to 17.3 years). At the initial evaluation, endocrine studies revealed that 40% of the patients were euthyroid, while 33% had compensated hypothyroidism and 27% had overt hypothyroidism. Seventeen patients, 16 of whom received thyroid hormone replacement therapy for a median period of 26 months, were followed up on a long-term basis after discontinuation of therapy. Seven (87%) of eight patients who were initially euthyroid have remained so for a median period of 28 months after treatment and a median period of 50 months since diagnosis. Four (44%) of nine patients who initially had hypothyroidism (either compensated or overt) have reverted to a euthyroid state and have remained so for a median period of 33 months after discontinuation of therapy. Neither the size of the thyroid gland nor the pattern or absolute titer of thyroid autoantibodies correlated with functional status. These results indicate that individuals with euthyroid JAT may remain euthyroid for many years and that a substantial percentage of patients with hypothyroid JAT will experience resolution of thyroid dysfunction.

Adolescent

Dominating redox systems in lakes and rivers; thermodynamic interpretation of in-situ measurements with a platinum electrode.

Thorough studies of 28 water bodies, predominantly lakes from the younger moraine area of Schleswig-Holstein, Northern Germany but also some peat bog waters in Niedersachsen, Northern Germany and lake Balaton in Hungary, showed the presence of at least six redox systems: NO3-/NO2-; NO3-/NH4+; NO2-/NH4+; So/HS-; So/H2S; and probably Fe(OH)3/Fe2+. Depending on the physico-chemical conditions one of these becomes the dominant system determining the electric potential measured with the platinum electrode. The platinum electrode does not respond to any oxygen dominated redox system. The corresponding theoretical redox equations seem to apply to almost all water bodies such as freshwater lakes, rivers, brackish water bodies, sea water and sometimes even humus rich water bodies from peat bogs and black water streams, hydromorphic soils, sediments and sewage sludge. The equations were found not to be valid for some heavily polluted effluents from lakes. The following points are discussed on the basis of these findings: the redox systems to which the normal platinum electrode reacts under natural conditions; equations of redox systems relevant in natural waters; methods of determination of the dominating redox system.

Electrochemistry

Liberation of surface and internal platelet-associated IgG (PA-IgG) during platelet activation.

The relationship between platelet-associated IgG (PA-IgG) of intact platelets to that of lysed platelets has been studied using a competitive ELISA. In platelets from 20 normal individuals mean surface PA-IgG constituted 35% of mean total PA-IgG and showed a significant linear relationship with total PA-IgG. In platelets from 61 patients with various forms of thrombocytopenia including that with immune causes, 38 showed a similar proportion of PA-IgG on the surface after storage at 2 degrees C, as seen in normal platelets, while in 23, levels of surface and total PA-IgG were equal. Normal platelets activated with thrombin or calcium ionophore A23187, also had levels of surface PA-IgG close to total PA-IgG. Supernatants of platelet suspensions activated with aggregating agents contained increased amounts of IgG and when the platelets were washed, both total and surface PA-IgG were decreased. Liberation of IgG from platelets was slower than that of [14C]serotonin but was decreased by release reaction inhibitors. Platelets treated at 2 degrees C with soluble heat-aggregated IgG, which binds to the Fc gamma receptor, showed increased surface PA-IgG, but, after incubation at 37 degrees C, although [14C]serotonin was released, PA-IgG levels were no longer increased. Thus since platelet activation, including that mediated by IgG binding to the Fc gamma receptor, causes PA-IgG release, levels of both surface-located and total PA-IgG may be affected by platelet activation, either in vivo, or in vitro during sample preparation and assay.

Blood Platelets

Different platelet specificities of heparin-dependent platelet aggregating factors in heparin-associated immune thrombocytopenia.

Delayed onset heparin-associated thrombocytopenia (HAT) is thought to be a result of formation of antiplatelet antibodies which cause platelet aggregation in the presence of heparin. Platelet aggregation in response to serum from patients with HAT has been studied in platelet-rich plasma (PRP) from a panel of normal blood donors. Heparin-dependent aggregation with any HAT serum occurred in PRP from only some donors. PRP from the non-responding donors did, however, aggregate in the presence of heparin with other HAT sera. The same patterns of aggregation or lack of response to HAT sera were seen in washed platelet suspensions. Heparin (0.06-2 U/ml) did not cause aggregation in the presence of normal serum with PRP from these donors. However, in PRP from four of the 17 individuals studied, heparin (0.25-1 U/ml) alone caused rapid platelet aggregation and some HAT sera heated at 56 degrees C caused platelet aggregation without added heparin. Sub-aggregating concentrations of adrenaline could replace heparin in promoting aggregation by heated HAT sera in PRP of the other donors. HAT IgG showed the same platelet specificities as the serum in causing either heparin- or adrenaline-dependent aggregation. Thus in HAT, antibodies are directed towards different platelet antigens which are expressed differently in different individuals. Platelet activation by heparin and adrenaline either exposes these antigens or causes aggregation of antibody-coated platelets.

Antibody Specificity

Iridotomy with red krypton laser.

Iridotomy with red krypton laser instead of blue-green argon laser was performed on 68 eyes with various types of angle-closure glaucoma. Patent iridotomy was obtained in all the eyes, mostly in one working session. In eight eyes secondary closure by pigment needed reopening with a few applications at the iridotomy site. There were no immediate or late complications of importance, the main advantage of the technique being the avoidance of the corneal epithelial and endothelial burns which commonly occur during argon laser iridotomy, particularly when the anterior chamber is shallow.

Glaucoma

The biological concept of race and its application to public health and epidemiology.

The category of race is widely used in public health. Although its significance may be clear-cut in some practical situations, an adequate theoretical construct for the concept of race does not exist. Public health appears to lag far behind the other biological sciences in the effort to grapple with the idea of race and its implications for the nature-nurture question. This paper outlines the current anthropological and social perspective on race, and applies this view to problems of disease epidemiology. It is proposed that uncritical use of the traditional biological concept of race has distorted etiological thinking in public health and has proven an obstacle in the development of effective intervention strategies. The pragmatism of medicine and its isolation from social science may account for much of this backwardness.

Cultural Characteristics

Autologous bone marrow transplantation using marrow incubated with Asta Z 7557 in adult acute leukemia.

The sensitivity of human myeloblastic leukemic (CFU-L) and normal hemopoietic stem cells (CFU-GM and BFU-e) to Asta Z 7557 (INN Mafosfamide) was studied with regard to autologous bone marrow transplantation (ABMT) with cleansed marrow for consolidation therapy in adult patients with acute leukemia (AL) in remission. Establishment of the dose-response curves for CFU-GM (n = 37), BFUe (n = 11), and myeloblastic CFU-L (n = 9) demonstrated a wide range of sensitivity from patient to patient for all three progenitors. Whereas CFU-L, CFU-GM, and BFU-e grown in semisolid cultures disclosed similar sensitivities to Asta Z 7557, long-term culture (LTC) studies (n = 41) indicated a higher resistance of early progenitors. In an effort to achieve a maximum tumor cell kill and yet spare a sufficient amount of normal stem cells to ensure consistent engraftment, we defined the optimal dose for marrow cleansing as the dose sparing 5% CFU-GM (LD95). This dose was established from a preincubation test (PIT) realized on a 10-mL marrow aspirate taken 15 days before marrow collection in each individual patient. Twenty-four adult patients while in remission of AL (20 in complete remission, four in partial remission) were consolidated by cyclophosphamide 60 mg/kg X 2 and total body irradiation at 10 Gy followed by ABMT with marrow cleansed by Asta Z 7557 according to the specification described above. Patients were divided in two groups: group 1, unfavorable prognosis (11 patients); group 2, standard prognosis [13 patients in first complete remission (CR)]. All patients engrafted on leukocytes (median day for recovery to 10(9)/L: day 30), patients with ALL recovered faster than patients with ANL (median day 19 v 34). Similarly, recovery of platelets to 50.10(9)/L occurred sooner in patients with ALL (median day 67, range day 23 through 90) whereas three patients with acute nonlymphoblastic leukemia (ANLL) in group 2 had to be supported with platelet transfusions for more than one year. In group 1, six patients had recurrent tumor within six months; three patients died from toxicity with no evidence of tumor. Two patients are still disease-free with a short follow-up (nine and ten months). In group 2, two patients died from toxicity with no evidence of leukemia three and 16 months post-ABMT. One patient with a M5 ANLL and one patient with ALL relapsed at six and 15 months, respectively. Nine patients have remained in CR or are disease-free with a median follow-up of 22 months.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent

Autologous marrow transplantation for patients with chronic myeloid leukemia in accelerated or blastic phase: report of 14 cases.

Between June 1979 and October 1983, 14 autografts were performed in 13 patients with CML (ten blast crisis, four accelerated phase). Results were disappointing: four patients died during aplasia; seven returned to chronic phase, but three died of hemorrhage, four relapsed, and three did not reverse. The main problem was the very low rate of successful engraftment. Both the collection of bone marrow after treatment with busulfan and a particular sensitivity of CFU-GM to cryoinjury were responsible for the infusion of very low doses of CFU-GM. However, we observed some promising results: In one patient in acute blast crisis, the Ph 1 chromosome disappeared, as well as the cytogenetic marker of transformation; in another patient with acute pure cytogenetic acceleration, the abnormal clone disappeared for 27 months; a third patient was maintained in a second chronic phase for 20 months. Thus we suggest that the results of autografting in chronic myeloid leukemia would be improved by infusing the largest possible dose of stem cells collected before or long after treatment by busulfan, and freezing them following a careful program.

Adult

The correlation between intraocular pressure and refractive status.

A comprehensive glaucoma screening of residents of three urban areas in southern Israel, aged 40 years and above, was performed between 1982 and 1984. Among other factors tested, intraocular pressure (IOP) and refractive status were recorded and the association between them was analyzed. Information on both factors was available in 2,403 (4,821 eyes) of the 2,594 persons participating. There were significantly more myopes among persons with IOPs of more than 20 mm Hg than with lower IOPs. Mean IOP increased gradually from 14.19 mm Hg in hypermetropes to 16.00 mm Hg among high myopes. Furthermore, the association between refractive status and IOP was stronger among Jews of North African or Asian origin than among Jews of European origin.

Adult

Chronic syndrome of inappropriate secretion of antidiuretic hormone in childhood.

Chronic forms of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) occur infrequently in childhood. We describe three pediatric patients with chronic SIADH. In two patients the persistent SIADH was associated with neoplasms of the central nervous system while in the third patient it was due to congenital anomalies of the central nervous system. We describe the clinical course and management of each patient, including the long-term use of furosemide taken orally once a day.

Child, Preschool

Plasma growth hormone response to oral l-dopa in infantile autism.

In order to assess further the occurrence of hypothalamic dysfunction in infantile autism and its possible relationship to dopaminergic abnormalities, the l-dopa provocative test was performed in 22 patients fulfilling DSM-III criteria for this disorder. The results indicate a high incidence (at least 30%) of blunted plasma growth hormone (GH) responses following oral administration of l-dopa in this sample. These data suggest an alteration of hypothalamic dopamine receptor sensitivity in the patients with blunted responses. Thus, a subgroup of autistic patients within a descriptively homogeneous diagnostic category shows evidence of hypothalamic dysregulation and dopaminergic abnormalities.

Autistic Disorder

Long-term outcome of primary acute angle-closure glaucoma.

Factors influencing the long-term cure of 116 consecutive cases of acute angle-closure glaucoma, with at least one year's follow-up were examined. Delay in presentation and the time needed to terminate the attack were found to have a detrimental effect on the final outcome, while the height of the intraocular pressure at the time of the attack was found to be unimportant in predicting the long-term prognosis of the disease.

Acute Disease

Long-term ocular hypotensive effect of levobunolol: results of a one-year study.

Data for the first 12 months are reported for an ongoing, multicentre, clinical study comparing the long-term, ocular hypotensive efficacy and safety of topical levobunolol (0.5% and 1%) and timolol (0.5%). This study was a double-masked trial testing 88 patients with chronic open angle glaucoma or ocular hypertension. During the 12-month period drops were instilled twice daily into both eyes after a washout of prestudy ocular hypotensive medication. The effect of the three treatments in reducing intraocular pressure (IOP) was similar. Mean IOP reductions over the 12 months averaged 7.2 mmHg for the 0.5% levobunolol group, 6.2 mmHg for the 1% levobunolol group, and 6.0 mmHg for the timolol group. Decreases in mean heart rate of up to 5 beats per minute were observed in the 0.5% levobunolol group, up to 8 beats per minute in the 1% levobunolol group, and up to 4 beats per minute in the timolol group. Several patients were removed from the study owing to side effects possibly related to levobunolol treatment.

Adult