Infection of the gonads of Glaucosoma hebvaicum by the nematode Philometva lateolabracis: occurrence and host response

The prevalence of infection of the West Australian dhufish Glaucosoma hebraicum off the lower west coast of Australia by Philometra lateolabracis was greater among females than males, which contrasts with the situation with Pagrus auratus in waters off New Zealand. Live P. lateolabracis were represented solely by females and were found only in the gonads of fish of mature size ( L ₅₀ at first maturity = c . 300 mm) caught between December and April and thus during the spawning period of dhufish. Since the gonads were largest during that period, they, and particularly ovaries, would provide an abundant food source in the form of blood. The prevalence of the parasite (live + dead individuals) increased with host body size to reach a maximum of c . 80% in the 700–799 mm length class of females and c . 50% in the largest length class of males. During the spawning period of G hebraicum, P. lateolabracis developed from small, non-gravid females to large gravid females, representing an increase in mass of more than 200 times. The maximum length of P. lateolabracis (470 mm) in G hebraicum is the greatest yet recorded for this species. Gonadosomatic indices provided no evidence that infection by P. lateolabracis leads to a conspicuous atrophy of the ovaries, which contrasts with the situation with the gonads of some of the teleosts infected by Philometra species, and presumably reflects, in part, the small volume of the ovary occupied by P. lateolabracis (c . 3%) and the low intensity of infection (mean = 2.0, maximum = 7). Although the presence of live P. lateolabracis did not stimulate an obvious tissue response by the ovaries during the spawning period of G. hebraicum , both the dead and any live parasites that remain after spawning become encapsulated in fibrous tissue.     

Treatment of Niemann-Pick disease type B by allogeneic bone marrow transplantation.

Allogenic bone marrow transplantation was carried out on a 3 year old girl with Niemann-Pick disease type B. Successful engraftment was achieved, and nine months after the procedure there was definite clearing of the sphingomyelin from the liver and pronounced clearing from the bone marrow. Any patient with Niemann-Pick disease type B complicated by early or severe hepatic impairment should be considered for bone marrow transplantation.     

Staphylococcal opsonization and anti-Staphylococcus aureus IgG subclass antibodies in patients with severe or recurrent S. aureus infections

Opsonization of Staphylococcus aureus (Oxford strain) and specific IgG subclass antibodies against formalised staphylococci were measured in plasmas from 27 patients with significant S. aureus infections and 35 healthy adults and 15 children. There were no statistically significant differences in the IgG2 and IgG4 levels between two groups and IgG3 was not detected, but the median plasma IgG1 level was significantly higher in patients with staphylococcal infections (P less than 0.00003). The concentration of IgG2 anti-S. aureus antibodies was 25-47 times greater than that of IgG1. If plasmas were decomplemented, the raised IgG1 levels were associated with increased opsonophagocytosis by normal neutrophils (P less than 0.0002).     

Induction of IL-1 secretion from human monocytes by Fc region subfragments of human IgG1

Peripheral blood-derived human monocytes and the murine P388D1-monocytes-like cell line are induced to secrete IL-1 when stimulated with Fc region but not F(ab) region subfragments obtained from the cleavage of human IgG1 with papain or pepsin. The portion of the Fc region of IgG1 responsible for stimulation of IL-1 secretion appears to be located within the C gamma 3 domain of the molecule. This hypothesis is supported by the observation that the biologically active pepsin-derived pFc' subfragment is located within the C gamma 3 domain and the long-term papain digests containing predominately Fc' are also active. In contrast, short term papain digests containing mostly intact Fc fragments were found to be unable to induce IL-1 secretion.     

Functional testing of hepatocytes following their recovery from cryopreservation

Various tests of function have been suggested for assessing hepatocytes recovered from cryopreservation. In this study we have investigated hepatocyte attachment during tissue culture and cellular density in order to assess function and compared them with two classical dye exposure tests. The ability of hepatocytes to exclude trypan blue dye (TB) and metabolize fluorescein diacetate (FDA) was demonstrated. In populations of freshly prepared hepatocytes 88.07% were able to exclude TB and 87.31% were able to metabolize FDA. However in populations of hepatocytes recovered after cryopreservation using 1.5 M dimethyl sulfoxide as cryoprotectant only 33.44% were able to exclude TB and 31.59% able to metabolize FDA. Both of these tests gave the same estimate of functional ability. Density gradient centrifugation of hepatocytes on Percoll 400 (Pharmacia, Uppsala, Sweden) separated two populations of hepatocytes; one (density ca.1.07 g/ml Percoll) in which most of the cells were able to exclude TB and the second (density ca. 1.02 g/ml Percoll) in which they were stained blue. The dense population was highly enriched in dye-excluding hepatocytes: freshly prepared hepatocytes, 92.4%, and cryopreserved hepatocytes, 88.66%. When samples of these cells (2 x 10(6) dye-excluding cells per dish) were tested for their ability to attach to tissue culture dishes only 17.28% of the cryopreserved hepatocytes were able to attach compared to 55.28% of the freshly prepared cells. We conclude that cryopreservation of hepatocytes produces a population of cells which are not metabolically identical to a population of freshly prepared hepatocytes even though they appear to have the same buoyant density and dye-excluding capabilities.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ecology of food microorganisms

The behavior of microorganisms in foods is governed by the constraints applied to the microflora by a variety of environmental and ecological factors. These include water activity, pH, E_h, chemical composition, the presence of natural or added antimicrobial compounds, and storage temperature, as well as processing factors such as the application of heat and physical manipulation. Control of these factors will govern whether the food spoils or not, whether any microbial health hazard arises, and whether desired microbial processes are successful or not. While much is known about the effects of individual environmental factors, the effects due to their interactions are less understood. The two main problems now facing the food microbiologist are optimization of environmental parameters and the selection of strains with specific properties. A better understanding of the mechanisms of action and interactions between the various environmental factors, coupled with the application of modern techniques to produce strains with particular properties, will lead to optimum use of food supplies and improvements in quality. There is also potential for the development of new and novel foods.     

Effects of oligomycin on the partial reactions of the sodium plus potassium-stimulated adenosine triphosphatase

The effects on phosphoenzyme (E-P) formation of ligands which activate Electrophorus (Na,K)-ATPase were investigated in the presence of oligomycin. When the enzyme was allowed to bind oligomycin in the presence of NaCl and MgCl2, subsequent addition of ATP plus KCl produced a monoexponential time course of E-P formation with a rate of 56 s-1, similar to the rate obtained in the uninhibited enzyme phosphorylated by ATP in the absence of KCl. Pi liberation under these conditions was slow and showed no initial burst phase, consistent with the inhibitory effect oligomycin has on the E1-P to E2-P conformational transition. Addition to KCl to a preincubation medium containing oligomycin, NaCl, and MgCl2 had no further effect on E-P formation. However, equilibration with oligomycin, KCl, and MgCl2 prior to the addition of NaCl plus ATP gave a much slower rate of E-P formation (5 s-1) and resulted in an initial rapid release of Pi similar to that found in the uninhibited enzyme. The slow increase in E-P level observed after incubation with oligomycin, KCl, and MgCl2 may be due to secondary formation of an inhibition complex following rapid binding of oligomycin. In contrast to the monophasic behavior which resulted from pre-exposure to NaCl or KCl, preincubation with oligomycin in the presence of MgCl2 plus Tris or Tris alone gave a biphasic pattern of E-P formation in which about 50% of the intermediate accumulated at a rate of 56 s-1 and the remainder at a rate of 5 s-1. In addition, the Pi burst amplitude was reduced, indicating partial inhibition of the enzyme. These results suggest that in the absence of Na+ and K+ only half of the enzyme is inhibited by oligomycin while the remainder undergoes inhibition subsequent to initiation of phosphorylation. Since the oligomycin concentration was saturating, the partial inhibition reflected in the biphasic pattern of E-P formation may be due to half-of-the-sites reactivity in which only half of the subunits bind oligomycin in the absence of monovalent cations.