Screening for toxoplasmosis in pregnancy.

The prevalence of antibody against Toxoplasma gondi in a population of 715 pregnant women has been evaluated by two methods: indirect haemagglutination antibody (IHA) and indirect fluorescent antibody (IFA) test and all positive sera were checked by the dye test. Five hundred of the study population were questioned on diet and on animal contact to elucidate a possible relation to the prevalence of antibody. Results are expressed in international units (IU) of antibody against T gondi. Of the 715 sera, 171 were positive by IHA and 173 by IFA. One hundred and sixty-seven sera were positive by both tests, ninety-eight (58%) correlating exactly, as to the concentration of antibody. The ten sera which were not positive by both tests all had detectable antibody at the minimum concentration only (12 IU). The dye test confirmed all sera positive by both tests with the exception of three. It also confirmed one of four sera positive by IHA antibody alone and two of six positive by IFA alone. All sera that proved dye test-negative had low antibody concentrations (12 IU) by IHA or IFA. The IHA test, which is commercially available in kit form, would be suitable for use as a screening test during pregnancy. The estimated annual rate of antibody acquisition over the age range 16-40 years is 1.2% per annum with the highest rate in the 36-40 age group (2.5% per annum) and the lowest in the 26-30 age group (0.4% per annum). The clinical history was not significantly different between those with and those without antibody against T gondi but significantly more women in the 36-40 age group had a history of animal contact than those in the 26-30 age group. No conclusive evidence of recent or current infection was found.     

Screening for asthma in children.

The primary health care team is at the forefront of asthma management and there is evidence of improved delivery of care via nurse run, audited, general practice clinics. However, hospital admissions for asthma continue to rise. Screening for childhood asthma would appear to have advantages for patient care. This review looks critically at the literature that addresses important issues in screening for childhood asthma, including the problem of defining asthma, its prevalence rate and the importance of dealing with asthma as part of a spectrum of illnesses of the upper respiratory tract. The fundamental principles of screening in relation to asthma are addressed, and five screening procedures are described and debated. Questionnaire studies are concluded to be relatively cheap and reliable, and a compilation of validated questions is described. Such questions could be tailored to individual practice needs and used in the early detection of asthma, giving the potential for early intervention and improved quality of life.     

Evidence for phosphoproteins in reovirus.

Reovirus type 3 was radioactively labeled by infecting L cells in the presence of ³²P₁. Approximately 0.1% of the total radioactivity in the purified virions could be assigned to phosphoprotein. Polyacrylamide gel electrophoresis of the phenol-extracted proteins showed that the majority of the ³²P label co-electrophoresed with the μ₂ polypeptide (molecular weight 72,000). The gel pattern was unaffected by treatment with DNase or RNase but, after trypsin digestion, the label was completely removed from the μ region. Chemical analyses were performed with a purified preparation of μ proteins and the results were consistent with ³²P-labeled phosphoserine residues in peptide linkage. Polypeptides from empty viral particles (top component) had a ³²P labeling pattern similar to that of infectious virions. Cyanogen bromide cleavage of the μ polypeptides indicated some selectivity in the phosphorylation of serine residues.     

Prospects for cure in leukaemia.

Patients with acute leukaemia have normal or near normal numbers of haemopoietic stem cells in their marrow at diagnosis. Remission is achieved when the administration of cytotoxic drugs eradicates the bulk of the leukaemic population while sparing normal haemopoiesis. The mechanism by which chemotherapy seems to act in this selective manner is essentially unknown. Nevertheless, remission rates of 80-95% can be achieved in children and in 50-80% of adults with acute leukaemia. Attempts to cure patients in remission may entail either "continuing curative chemotherapy" or "supralethal" doses of chemoradiotherapy followed by autologous or allogeneic bone marrow transplantation. The relative merits of these different methods remain highly controversial but chemotherapy is usually the preferred method of continuing treatment for children with acute lymphoblastic leukaemia in first remission; and allogeneic transplantation is recommended for younger adults with acute myeloid leukaemia who have suitable HLA-identical sibling donors. The role of autografting is still experimental. Patients with chronic myeloid leukaemia can achieve long term remission and probably cure following allogeneic bone marrow transplantation but the resultant risks of mortality are still appreciable. Chronic lymphocytic leukaemia currently remains incurable.     

Host defense in cryptococcosis. I. An in vivo model for evaluating immune response.

An inbred mouse model was used to evaluate in vivo host immune response to Cryptococcus neoformans. Within 1 week of immunization, mice developed delayed type hypersensitivity reactions (DTH) to cryptococcal extracts derived from either culture filtrates or disrupted cells. There was no significant cross reactivity with extracts of other fungi. Previous immunization provided considerable protection against subsequent challenge with multiple strains of cryptococci. DTH also developed after nonimmunized mice were challenged with C. neoformans; however, in this situation DTH was not associated with prolonged survival. These studies indicate that mice can be immunized and protected against cryptococcosis and that this protection is associated with acquisition of DTH to cryptococcal antigens.     

Inking in Aplysia californica. III. Two different synaptic conductance mechanisms for triggering central program for inking.

1. In the previous two papers we described the motor elements which mediate all-or-none inking behavior in Aplysia (4) and the contribution of specific membrane properties of the ink-gland motor cells to the central program for inking (5). In the present paper we show that the central program for inking (a characteristic accelerating burst of action potentials in the motor cells) can be triggered in two different ways: 1) by means of a suprathreshold stimulus delivered to a single site on the animal; and 2) by means of two subthreshold stimuli closely spaced in time, delivered either to the same or to different sites on the animal. 2. The single suprathreshold stimulus triggers the central program primarily by means of a complex increased-conductance EPSP. The two subthreshold stimuli trigger the program by means of a complex decreased-conductance EPSP which is capable of augmenting subsequent afferent synaptic input. 3. The synaptic augmentation produced by the decreased-conductance EPSP is attributable to two properties of the EPSP: 1) it increases the input resistance of the ink-gland motor cells so that the synaptic current from afferent input onto the cells produces larger, more effective EPSP's; and 2) it increases the electrotonic coupling among the motor cells, thereby producing increased positive feedback among them. Thus, the decreased-conductance EPSP provides a novel mechanism for spatial and temporal summation.     

Arginine vasopressin metabolism in dogs. I. Evidence for a receptor-mediated mechanism.

The plasma clearance rates (PCR) of arginine vasopressin (AVP), and iodinated AVP (125I-AVP) were determined after pulse injection in conscious water-loaded dogs. Both the PCR and the apparent initial volume of distribution were significantly greater for AVP than for the biologically inactive iodinated AVP 37.4 +/- 4.8 ml/kg per min vs. 6.7 +/- 0.8 ml/kg per min (P less than 0.001) and 12.7 +/- 0.9% body wt vs. 7.1 +/- 0.4% body wt (P less than 0.001). AVP clearance was then determined by the constant-infusion technique at doses that produced equilibrium AVP concentrations within and above the physiological range. AVP-PCR was 37.4 +/- 7.1 ml/kg per min at 34 microU/kg per min, which was comparable to that after pulse injection (P less than 0.9). AVP clearance fell progressively, and urine osmolality progressively increased with increasing AVP infusion rates to plateau values at 136 microU/kg per min; a strong negative correlation was observed between mean AVP-PCR and urine osmolality (r = -0.993). The data suggest a relationship between the biological activity of AVP and its clearance. It is proposed that plasma membrane receptors may mediate a portion of the metabolic clearance of AVP.     

Pressure drops in cannulas for hemodialysis.

Pressure drops in cannulas for hemodialysis have been measured in vitro in both flow directions for five different viscosities and up to 600 mL/min flow Cannula dimensions were 15, 16 and 17 gauge and 15, 20 and 25 mm nominal length. The measurements were taken at room temperature with glycerin solutions as test fluid. RESULTS: The pressure drops can be described by a second order function but not by the Hagen-Poiseuille law even when corrected for inlet and outlet effects as described by Bernoulli's law. Pressure drops depend on flow direction. Back-eyes and cannula tips have no influence on the pressure drop. Pressure drops and especially flow direction asymmetry are influenced by the hydraulic design of the connection piece between cannula and tubing. The results can be used for prediction of pressure drops in cannulas allowing better use of pressures already measured in the extracorporeal circuit of hemodialysis machines.