Quantitation of serum gentamicin concentration by a solid-phase immunofluorescence method

We describe the use of a solid-phase immunofluorescence method (FIAX system) for measuring drug concentrations, specifically gentamicin, in serum or plasma. Antibody to gentamicin is immobilized on a polymeric surface. This Sampler is immersed in a mixture of serum standard or unknown and a buffered solution of fluorescent-labeled gentamicin. After 30 min, the fluorescence of the specifically bound labeled gentamicin is measured with a fluorometer. The assay detects gentamicin in concentrations as low as 50 mug/L. It is specific for gentamicin, cross reactivity to some other therapeutic drugs, except netilmicin and sisomicin, being low. Results by this assay compare well with those by a radioimmunoassay (r = 0.94) and a radioenzymic assay (r = 0.95). The assay is specific, economical, simply performed, requires little pipetting, and does not involve the use of radioisotopes.

The management of chronic schizophrenia

With the movement of psychiatric patients from chronic mental hospitals to local communities over the past 20 years, family physicians have provided care for increasing numbers of chronic schizophrenia patients. The residual symptoms which these patients demonstrate require special communication skills on the part of the physician if a collaborative patient-physician relationship is to be established. The management of the disease should be founded on an understanding of its psychopathology. In this paper, the authors describe this psychopathology and suggest therapeutic interactions and interventions specific to the disease process.

Cytogenetic analysis of a case of "13q- syndrome" (46,XX,del 13) using banding techniques

Many chromosomal syndromes include ocular anomalies. In the del(13q) syndrome retinoblastoma, coloboma, and microphthalmia may be present. In the del(13q) case we report, the findings include colobomas and apparent microphthalmia, although the retinoblastoma sometimes associated with this condition was not observed. More precise descriptions of the del(13q) syndrome relative to the region deleted using improved banding techniques may: (1) increase the likelihood of accurate diagnosis, (2) enhance clinical predictions, and (3) possibly further clarify the genetic control over the development of the ocular system.

Regulation of the microtubule steady state in vitro by ATP

ATP increases microtubule steady state assembly and disassembly rates in vitro in a concentration-dependent manner. Bovine brain microtubules, composed of 75% tubulin and 25% high molecular weight microtubule-associated proteins (MAPs), were purified by three cycles of assembly and disassembly in the absence of ATP. When assembled to steady state, these microtubules add dimers at one end and lose them at the other in a unidirectional assembly-disassembly process. In the presence of 1.0 mM ATP the unidirectional flow of tubulin from one end of the microtubules to the other increases as much as 20 fold, as revealed by loss of 3H-GTP from uniformly labeled microtubules under GTP chase conditions and by the rate of disassembly following addition of 50 microM podophyllotoxin. UTP, CTP and 5' adenylylimidodiphosphate (AMP-PNP) cannot substitute for ATP in producing this effect. Furthermore, the increase in steady state flow rate persists afer ATP is removed. Thus microtubules assembled in ATP and centrifuged through sucrose cushions to separate them from nucleotides continue to exhibit increased rates in the next assembly cycle in the absence of ATP. It is possible that an ATP-dependent microtubule protein kinase is responsible for the observed increase in tubulin flow rate. A kinase activity associated with brain MAPs has been reported to be cAMP-dependent (Sloboda et al., 1975). We have found an adenylate cyclase activity associated with these microtubules. Whether the adenylate cyclase is a contaminant or due to a specific microtubules-associated protein, and whether its activity is functionally linked to the increased rate of assembly and disassembly in the presence of ATP, remain to be determined.

Image feature extraction using diameter-limited gradient direction histograms

Features extracted by operators which examine diameter-limited gradient direction histograms are important because they describe images of industrial workpieces efficiently and have the potential for rapid computation via special purpose hardware. When such operators are passed over an image in raster fashion, features such as the following are detected: a strong peak in the direction histogram indicating the presence of a relatively straight edge, a second strong direction indicating a corner, a wide direction group indicating a curved edge, and a uniform distribution of directions over the histogram indicating small holes. Diameter-limited optimization can be used to substantially reduce the number of pixels which have been given feature labels by such operators without losing descriptive power. Feature labels for direction histograms having a second strong direction, a wide direction group, or a uniform distribution might be retained only if all other pixels within a circular aperture have a lower bin value. Pixels with a strong direction label might be retained only if all other pixels within a circular aperture and along the gradient direction have a smaller bin value. Tracking can then be applied to the remaining strong direction pixels in the direction perpendicular to the gradient to achieve representation of edges by endpoints. Experimental results indicate that descriptions which are compatible with human interpretation can be achieved.

The role of dietary fat and hepatic triglyceride secretion in cancer-induced hypertriglyceridemia

Growth of Ehrlich ascites carcinoma induces hyperlipemia in mice. In the present study using male Swiss-Webster mice, we examined whether the usual elevations of plasma triglyceride levels in cancerous mice would occur in the absence of dietary fat. Hypertiglyceridemia developed at a similar rate and to a comparable degree in tumerous mice eating a fat-free (58% glucose) diet and in those fed Purina chow. Maximal hyperlipidemia was observed on day 6 or day 8 in tumorous mice fed either diet. To determine whether the endogenous cancer-induced hyperlipidemia was due to hypersecretion of triglycerides by the liver, triglyceride secretion rates were studied 0, 2, 4, 6, 8, 10, and 12 days after tumor inoculation using Triton WR-1339. The secretory rates did not increase prior to or during the development of hypertriglyceridemia in tumorous mice and were not significantly different from those of control mice. On days 10 and 12, triglyceride secretion actually decreased in tumorous mice. Other possible causes for hypertriglyceridemia are discussed in light of the present findings of undetectable differences in triglyceride secretion rates accompanying growth of Ehrlich ascites carcinoma in mice.

HLA phenotype frequencies in individuals with cleft lip and/or cleft palate

The HLA types of 133 patients with cleft lip and/or cleft palate were determined. Caucasian patients with isolated cleft palate showed a possible association with HLA. Ten of 11 male patients had HLA--A2 as compared to one out of eight female patients (P less than 0.005). Caucasian males with cleft lip and cleft palate had a slight increased frequency of HLA--Aw24 (P = 0.07) and Mexican-American males with cleft lip and/or cleft palate showed an increase of antigen HLA-A28 (P = 0.07), though neither were statistically significant. Females with cleft lip and/or cleft palate from either racial group had no differences from the controls. The serum from 90 mothers of patients with cleft lip and/or cleft palate were reacted against their child's lymphocytes. Of these crossmatch tests, 12% were found to be positive. These preliminary results suggest that male patients with isolated cleft palate are worthy of further studies with respect of HLA associations.

Evidence for involvement of microtubules in the action of vasopressin in toad urinary bladder. II. Colchicine binding properties of toad bladder epithelial cell tubulin

Colchicine, podophyllotoxin and vinblastine have been found to inhibit the action of vasopressin on water movement in the toad urinary bladder. Tubulin is the major colchicine binding component of toad bladder epithelial cells, accounting for approximately 3.3% of the total cell protein. More than 99% of the tubulin is found in the soluble fraction after sonication, the remainder is in the particulate fraction. Similar to the characteristics of the binding of colchicine to tubulins from other sources, the binding of colchicine to toad bladder tubulin is temperature- and time-dependent, is inhibited competitively by podophyllotoxin (Ki= 5.5 x 10(-7)m), and has a binding constant of 1 X 10(6) liters/mole at 37 degrees. Binding activity decays according to first-order kinetics and is stabilized by vinblastine. The characteristics of the interactions of colchicine and podophyllotoxin with epithelial cell tubulin in vitro closely parallel the ability of these drugs to inhibit the response to vasopressin in vivo. These results, coupled with those of functional and morphological studies, support the view that the ability of these drugs to affect vasopressin-induced water movement across toad bladder epithelial cells is related to the depolymerization of cytoplasmic microtubules.

Psoriasis treated with clobetasol propionate and photochemotherapy

Comparable lesions in 16 patients with chronic plaque psoriasis were treated with clobetasol propionate or placebo ointments for 1 week before beginning photochemotherapy. The greater improvement of the steroid treated lesions was maintained after the ointment was withdrawn and there was a mean period of 31 days before those treated with placebo showed a comparable response to photochemotherapy. By the end of the study 8 patients were completely free of psoriasis, healing being achieved after a mean of 7.2 photochemotherapy treatments on the steroid treated lesions compared with 13.5 where a placebo ointment was used. No patient had any adverse reaction to treatment.

Opposite end assembly and disassembly of microtubules at steady state in vitro

Measurements of tubulin exchange into and from bovine brain microtubules at steady state in vitro were made with 3H-GTP as a marker for tubulin addition to or loss from microtubules. Tubulin has an exchangeable GTP binding site that becomes nonexchangeable in the microtubule. We found that tubulin addition to and loss from microtubules under steady state conditions occurred at equivalent rates, that loss and gain were linear, and that exchange rates (percentage of total tubulin in microtubules lost or gained per hour) were dependent upon microtubule length. Furthermore, we found that podophyllotoxin blocked steady state assembly, but did not alter the rate of steady state tubulin loss. When the assembling microtubule end was pulsed with 3H-GTP at steady state, the label was almost completely retained during a subsequent chase. We conclude that the microtubule assembly-disassembly "equilibrium" is a steady state summation of two different reactions which occur at opposite ends of the microtubule, and that assembly and disassembly occur predominantly and perhaps exclusively at the opposite ends under steady state conditions in vitro.

Structure of the tubulin dimer

Microtubules are formed from a 110,000-dalton dimeric subunit called tubulin. Two forms of 55,000-dalton monomer, alpha and beta, are found in all microtubule preparations. The dimers could thus theoretically be either heterodimers (alphabeta) or homodimers (alphaalpha and betabeta). This problem was investigated by stigated by chemical cross-linking using several bifunctional reagents, of which one, dimethyl-3,3-(tetrame thylenedioxy) dipropionimidate dihydrochloride (DTDI), was able to make intradimer bonds in tubulin. When soluble chick brain tubulin was cross-linked with DTDI and analyzed by electrophoresis in an acrylamide gel system capable of resolving alphaalpha, alphabeta, and betabeta, 60 to 90% of the cross-linked dimer was alphabeta. If tubulin was incubated at 24 degrees prior to cross-linking with DTDI the total yield of cross-linked dimer increased with time, indicating that tubulin was forming loose aggregates. The relative amounts of cross-linked dimer alphaalpha and betabeta also increase with time, indicating that soluble tubulin is largely alphabeta, and suggesting that cross-linked alphaalpha and betabeta arise from nonspecific aggregation during tubulin purification. The aggregation observed by cross-linking with DTDI was strongly influenced by colchicine and Vinca alkaloids in a pattern similar to the effects of these drugs on tubulin polymerization.