Distribution and chromosomal polymorphism of the malaria vector Anopheles dirus species D.

Preliminary results indicate that species D of the Anopheles dirus complex is widespread west of the Thai-Burma border in Burma and Bangladesh. A chromosomal study of An. dirus species D in these areas has revealed that this malaria vector is highly polymorphic for chromosomal rearrangements in salivary gland polytene chromosomes. The data from the limited number of wild-caught samples suggest that different geographically isolated populations may occur with respect to the frequency of inversions 2La, 3Ra and 3La. The distribution of chromosomal polymorphisms may be associated with the geography and epidemiology of human malaria in this region.

Immunohistochemical study of Ia antigen in the normal and diseased human kidney.

The presence and distribution of Ia antigen in normal human kidneys and biopsy specimens from patients with renal disease were investigated by immunohistochemical techniques using two monoclonal antibodies to the nonpolymorphic determinants of human HLA-DR molecules. Ia antigen was found on the endothelium of glomerular and peritubular capillaries and of veins and vasa recta. Loss of endothelial staining was found in necrotic and sclerotic glomerular and tubulointerstitial lesions. Staining or decreased staining was also not found in the severe proliferative nephritis of systemic lupus erythematosus although endothelial cells could still be identified upon light microscopic examination of the same biopsy specimen. Resting and proliferating cells in mesangial areas did not stain with anti-Ia antibody and extracapillary proliferating cells did not express Ia antigen except for occasional cells in anti-GBM crescentic glomerulonephritis, suggesting that Ia-bearing cells are not involved in mesangial and most extracapillary proliferations in human glomerulonephritis. All clustered mononuclear cells infiltrating the renal interstitium stained with anti-Ia antibody regardless of the type of nephritis where infiltrates occurred.

Immunoelectron microscopic study of plasma protein pathways through the abnormal intestinal vasculature of HgCl2 induced immune disease in brown Norway rats.

Localization of immune deposits (ID) and the pathway of circulating serum proteins through the intestinal vasculature have been studied in 40 Brown Norway (BN) rats poisoned by mercuric chloride, using anti-peroxidase IgG as tracer. ID were found in all vessels but were initially detected along the epithelial basement membrane of villi and in pericytic venules and veins. ID were found in all the layers of the vessel walls. In pericytic or myocytic vessels, no ID were detected outside the adventitial lamina densa. ID trapped non immune IgG. Abnormal pathways were only found in venular capillaries and in pericytic venules with large gaps between endothelial junctions. ID were particularly abundant in these vessels.

Immunoelectron microscopic study of plasma protein pathways through the different segments of the rat intestinal vasculature.

Nineteen Brown-Norway (BN) rats received intravenous injections of sheep anti-peroxidase (HRP) antibodies. Four BN rats were immunized to HRP. The anti-HRP antibodies were used to trace permeability pathways of large physiological molecules across different vessels of the small intestine. This organ was chosen because of the possibility of convenient "in situ" fixation and for the diversity of vessel types it contains. It was shown that: 1) There were no obvious transendothelial pathways in arteries with an elastic lamina. 2) The antibodies readily crossed fenestrated capillaries through the fenestrae. 3) There were two possible pathways through muscle capillaries and pericytic venules, namely transcytoplasmic vesicular "cactus-like" channels and interendothelial junctions. 4) Interendothelial permeability was a possible factor in veins with an elastic lamina. 5) Lymphatics were readily permeable through intercellular junctions and cytoplasmic vesicles.

Immunoenzymatic study of the protein pathway through the glomerular barrier in rat glomerulonephritides.

Circulating anti-horseradish peroxidase (HRP) IgG antibodies were used in the rat to study the glomerular leakage of proteins in glomerulonephritis (GN) induced by aminonucleoside (AN) and in glomerulonephritis induced by mercuric chloride to produce anti-glomerular basement membrane (GBM) antibodies. In ANGN, autologous albumin and fibrinogen were also detected by immunoperoxidase techniques. In both types of GN, the proteins studied were observed in the glomerular urinary space and proximal tubular cells. No channels were visible in the lamina densa. No accumulation of proteins was seen under the epithelial slits that were not closed. In ANGN, accumulation of proteins was observed in the subepithelial space where the podocytes act as a barrier (closed slits, subepithelial blind pockets, areas covered by broad sheets of cytoplasm), but no accumulation was seen in the lamina rara externa under normal or enlarged slits and areas of large epithelial cytoplasm detachment. Statistical analysis showed that in ANGN, at the time of maximal proteinuria, the number of "micropinocytotic" vesicles in the GBM-embedded part of podocytes was not increased as compared with controls. Such vesicles were not labeled. We conclude that in both types of GN, the permeability of the GBM is diffusely increased and that the plasma proteins pass into the urinary space via an extracellular pathway.

Mechanism of glucocorticoid-induced inhibition of prostaglandin synthesis.

In order to study the mechanism of steroid-induced inhibition of prostaglandin (PG) secretion, we have used rat renomedullary interstitial cells grown in tissue culture as an in vitro model. These cells have been shown by radio-immunoassay to produce high amounts of prostaglandins, mainly PGE2 and PGF2 alpha. Using (3H) dexamethasone, we have demonstrated in our cultures the existence of glucocorticoid binding sites which exhibit all the characteristics of physiological glucocorticoid receptors. Comparison between the biological activity (i.e. the ability to inhibit PG secretion) of the various steroids tested (dexamethasone, corticosterone, aldosterone, progesterone and estradiol) and their affinities for the glucocorticoid binding sites reveals a striking correlation between these two parameters. Steroids which bind to the receptors also inhibit prostaglandin secretion whereas testosterone and estradiol, which have a very weak affinity for the glucocorticoid binding sites do not inhibit PG secretion. In addition, actinomycin D (0.1 microgram/ml) and cycloheximide (0.1 microgram/ml) are able to abolish the inhibitory effect of dexamethasone on PG secretion. Our results indicate that the action of corticosteroids on prostaglandin secretion, which is believed to be the basis of their anti-inflammatory properties, is mediated through receptor occupancy and requires RNA and protein synthesis.

Distribution of heterologous antiperoxidase antibodies and their fragments in the superficial renal cortex of normal Wistar-Munich rat: an ultrastructural study.

The distribution of serum proteins in the superficial renal cortex of normal Wistar-Munich rats was studied using a new technique. Heterologous antiperoxidase antibodies (160,000 daltons), their F(ab')2(100,000 daltons), and Fab (50,000 daltons) fragments were injected intravenously and then demonstrated by incubation with free peroxidase after in situ fixation. This technique offered several advantages including easy and uniform detection of the proteins, even in tubular cells, and a high degree of specificity and accuracy. Four findings emerged from this: (1) The glomerular filtration barrier was found to be complete for IgG and incomplete for (ab')2 and Fab fragments. (2) This barrier for IgG was localized in the lamina densa. (3) The filtered proteins were found to be reabsorbed and degraded in the proximal tubule. (4) The three proteins were diffusely detected in the interstitial tissue and in tubular intercellular spaces up to apical tight junctions.

Ultrastructural evidence, by immunoperoxidase technique, for a tubular reabsoprtion of endogenous albumin in normal rat.

The reabsorption of endogenous albumin in the proximal tubules of the normal Munich-Wistar rat has been studied using immunoperoxidase techniques. The lumina of the superficial proximal tubules were found to remain open after in situ fixation, allowing good penetration of the conjugates. Labeling typical of an endocytotic process was observed only in the proximal tubules. This fact suggests that the glomerular filtration barrier is not an absolute one for denogenous albumin.

Evaluation of the Dirofilaria immitis filarial skin test antigen in the diagnosis of filariasis.

Conflicting opinions on the value of a skin test in the diagnosis of human filariasis emphasized the need for a careful examination of this procedure. The evaluation was made by asking workers in different countries to use an antigen prepared from Dirofilaria immitis in groups of people who could be examined for parasitic infection.In one non-endemic area, repeated tests over a 1-year period did not lead to sensitization, but the reactions of individuals varied from test to test. In endemic areas of filariasis, exposure to infective bites seemed to influence the pattern of skin reactions to a greater degree than did the development of overt infection with Wuchereria bancrofti. No particular size of reaction could be considered indicative of filarial infection.THE VALUE OF THE SKIN TEST WITH THIS ANTIGEN SEEMS LIMITED TO TWO SITUATIONS: (1) a large reaction may help to confirm a clinical diagnosis of filariasis when parasites cannot be found, and (2) the frequency distribution of skin reaction sizes in local populations may help, where blood surveys are impossible, to indicate areas in which some filarial infection is being transmitted.Results of skin test surveys should be expressed as frequency distributions of reaction sizes and negative/positive classification should be avoided.

Outdoor resting of Culex pipiens fatigans in Rangoon, Burma.

The sites occupied by resting adult mosquitos are of importance, since they may be accessible to treatment with insecticide. It has usually been assumed that Culex pipiens fatigans feeds and rests indoors, thus making itself vulnerable to indoor spraying. However, work in the Kemmendine Experimental Area of Rangoon, Burma, has now shown that many C. p. fatigans rest out of doors in a variety of shelters. The lower parous rate in outside catches as compared with indoor catches tends to confirm the view that newly hatched C. p. fatigans rest out of doors for some time before setting off to feed. The percentage of infected mosquitos is remarkably constant from site to site and from month to month and does not differ significantly from that obtained in indoor resting catches or on bait out of doors. It appears that the possibility of acquiring infection out of doors will have to be seriously considered in any anti-filariasis campaign.