Studies with Brugia pahangi. 18. Anthelmintic effects of stibocaptate

Stibocaptate (Asiban, Hoffman--La Roche) killed third stage larvae of Brugia pahangi in vitro at 50 p.p.m. but had no effect on microfilariae at 1 X 10(4) p.p.m No larvae developed in infected mosquitoes fed 1% stibocaptate in 10% sucrose. It was neither micro-nor macrofilaricidal in either jirds or cats but did affect embryogenesis.

Studies with Brugia pahangi 17. The anthelmintic effects of diethylcarbamazine

Diethylcarbamazine (DEC) was active in vitro against infective larvae and microfilariae of Brugia pahangi but only at high concentrations. When fed to mosquitoes which were infected with B. pahangi it had little or no activity. In jirds it was inactive against B. pahangi microfilariae and adults when administered at 300 mg/kg for 5 days either by the intraperitoneal or oral route. In cats given 25 or 50 mg DEC/kg intraperitoneally on 3 or 5 occasions it was not microfilaricidal, but most of the adult worms died within 30 days of the end of treatment. Although most microfilariae disappeared from the blood of cats immediately (i.e., within an hour) after treatment, they reappeared within a few hours in the same numbers. Microfilarial levels were reduced after treatment but there was no precipitate decline as occurs in human B. malayi patients.

Intrauterine development of the microfilariae of Dipetalonema viteae

The egg shell of Dipetalonema viteae separated from the oolemma and became highly convoluted at an early stage of development. No second oolemma or trilaminate membrane was seen. Channels containing electron dense material (thought to be nutrient material from the uterine wall) were formed between adjacent embryos. Many developing embryos died. Microvilli were formed by the uterine wall and developing embryos were closely apposed to these (again presumably to obtain nutrient). Embryos emerged from the egg in the uterus and were born as unsheathed microfilariae.

Studies with Brugia pahangi. 20. An investigation of 23 anthelmintics using different screening techniques

23 anthelmintics were tested against Brugia pahangi microfilariae and infective larvae in vitro and in Aedes aegypti infected with B. pahagi and jirds (Meriones unguiculatus) infected with a B. pahangi/patei hybrid. There was little correlation between the results obtained in vitro and in infected insects and the results obtained in these tests gave no indication of the activity in jirds. Three of the compounds were macrofilaricidal in jirds and these were tested in cats infected with B. pahangi. One of these--5-benzamido-2(4-thiazolyl)-benzimidazole--was macrofilaricidal in cats and it is suggest that it should be tested in other filarial systems. It is concluded that the insect and in vitro tests are not good primary screens for filaricidal activity.

Serum lysozyme, antinuclear factors and antibody to native DNA

This work was done in order to investigate the previously reported antinuclear property of lysozyme (LZM). Addition of human or hen egg white lysozyme (hLZM or eLZM) to normal serum and to 11 sera with different types of antinuclear factors (ANF) produced no consistent changes in ANF titre or type. Likewise, absorption of LZM from the sera with bentonite failed to influence ANF titre and, finally, hLZM and eLZM were incapable of binding native DNA (nDNA). Elevated serum lysozyme levels in rheumatic diseases are therefore unlikely to produce false-positive results in tests for antinuclear antibodies.

Effects of vagal stimulation, atropine, and propranolol on fibrillation threshold of normal and ischemic ventricles

The effects of electrical stimulation of the vagus nerves and the administration of atropine on ventricular fibrillation threshold (VFT) were studied in open-chest hearts of 15 dogs anesthetized by alpha-chloralose. These studies were made in both normal and ischemic ventricles, i.e., before and during acute coronary occlusion. The ventricles were paces at a constant rate to eliminate rate-dependent changes and the minimal current required to induce ventricular fibrillation (or VFT) was determined by delivering a train of rapid rectanglular pulses (100 per second) to the venticle actoss the vulnerable period. In normal ventricles, VFT's were significantly increased by vagal stimulation (P less than 0.01) and decreased by atropine (P less than 0.05). Coronary occlusion markedly decreased VFT's (P less than 0.01), and vagal stimulation or atropine failed to alter VFT's significantly in these ischemic ventricles (P greater than 0.8). In additional 14 dogs, the effects of vagal stimulation and atropine were studied after the administration of propranolol. Propranolol alone increased VFT's significantly in boetreatment with propranolol, vagal stimulation and atropine failed to change VFT's significantly in both normal and ischemic ventricles (P greater than 0.8). These results indicate that the vagus nerves exert their effect on VFT by modifying the sympathetic nerve activity in normal ventricles, but such an effect is not significant enough to alter VFT in ischemic ventricles.

Studies on Brugia pahangi. 13. The anthelmintic effect of compounds F151 (Friedheim), HOE 33258 (Hoechst) and their reaction product

F151 was a potent filaricide against adult Brugia pahangi in cats and jirds. HOE 33258 did not kill adult worms in cats but had a marginal effect on adult worms in the peritoneal cavity of jirds. It was not immediately microfilaricidal in cats but the microfilarial counts of treated cats fell within a few weeks of treatment. The reaction product, or mixture, of these two compounds (V5851 = E) was strongly macrofilaricidal in cats and jirds.

Studies with Brugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species

The intrauterine development of Brugia pahangi embryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of the B. pahangi embryo is distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine lumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

Fat body: a site of hemoglobin synthesis in Chironomus thummi (diptera)

Fourth instar larvae of Chironomus thummi were permitted to incorporate labeled amino acids and/or sigma-aminolevulinic acid (sigma-ALA) in vivo and in organ culture. The products secreted into the hemolymph or into the culture medium were examined by acrylamide gel electrophoresis. Nine electrophoretic bands can be resolved as hemoglobins without staining. When gels are sliced for scintillation counting, incorporated amino acids and sigma-ALA are shown to be associated primarily with the same nine hemoglobin bands, suggesting that hemoglobins are assembled and secreted. Staining of gels with Coomassie brilliant blue reveals that there are several bands in addition to the visible hemoglobins. These bands incorporate amino acids, but not sigma-ALA, suggesting that they are non-heme proteins. The results of culturing isolated salivary glands, gut, and fat body demonstrate that the fat body is the major site of hemoglobin synthesis and secretion. Labeled products of the gut represent about 5% of the total hemoglobins produced by the tissues, while no hemoglobins are produced by the salivary glands. Although nine hemoglobins are visibly resolved on gels, labeling techniques reveal as many as 14 hemoglobins. This is the first demonstration of hemoglobin synthesis by specific tissues in culture in an invertebrate.

Studies with Brugia pahangi 12. The activity of levamisole

The effects of levamisole on adults, third stage infective larvae, and microfilariae of Brugia pahangi were studied in in vitro culture and in vivo against developing stages in the vector mosquito and in infected cats. In vitro the drug was effective only at dose levels much higher than can be tolerated by mammals. It was active against the developmental stages of the worm in the vector Aedes aegypti. The drug was strongly microfilaricidal in cats but less effective against adult worms.

Surface strain distribution in isolated single lumbar vertebrae

The surface strains of isolated single lumbar vertebrae under compressive load were examined by the techniques of brittlecoat and photoelastic analysis. Directions of principal strain components have been determined. Areas of stress concentration were found around the vertebral rims, near the pedicles, and around the foramina of the basivertebral veins.

Xeroradiographic visualization of trichinae in polar bear muscle

Gould (1970) stated that “asyet,roentgenographic technics cannot demonstrate trichinae in skeletal muscle”. We have found no report of X-ray film demonstration of Trichinella cysts in muscle in the literature to date. Rogers et al. (1975) used the technique of xeroradiography to show living and calcified filarial worms (Brugia pahangi) in the infected lymphatics of cats and we have had an opportunity to use this method to examine calcified Trichinella cysts in infected muscle.

Studies with Brugia pahangi. 11. Measurement of lymph flow in infected cats

Rates of lymph flow in cats were measured by calculating the disappearance of radioactive colloidal gold (198Au) from the feet of (1) uninfected cats, (2) cats infected for various periods after primary infection with Brugia pahangi, and (3) cats repeatedly challenged with B. pahangi infective larvae over long periods. The results of the study showed that (1) there is great variation in gold disappearance rates in different cats in all 3 groups above, (2) the cat lymphatic system is functionally highly efficient, and (3) in a cat with lymphoedema and early elephantiasis, there was a significant impairment of gold removal from the affected foot. The study proved useful in finding lymph drainage rates in the various animals but did not, as hoped, show any pattern of lymph flow decrease which might have enabled the use of the technique as a diagnostic tool for lymphatic pathology prior to the occurrence of external clinical manifestations of filariasis.

Studies on Brugia pahangi 9. The longevity of microfilariae transfused from cat to cat

Microfilariae in whole uncentrifuged cat blood were transfused from infected to normal cats. The recipient cats were bled frequently and the life-span of the microfilariae in the peripheral circulation was determined; The life-span on microfilariae in different cats was ver variable. Microfilariae were detected fro 2-136 days after inoculation. In immunized cats microfilariae could not be detected 18 hours after inoculation. Any attempt to concentrate or clean the microfilariae caused them to disappear from the circulation more quickly.

Effects of aminophylline on the threshold for initiating ventricular fibrillation during respiratory failure

Cardiac arrhythmias have frequently been reported in association with respiratory failure. The possible additive role of pharmacologic agents in precipitating cardiac disturbances in patients with respiratory failure has only recently been emphasized. The effects of aminophylline on the ventricular fibrillation threshold during normal acid-base conditions and during respiratory failure were studied in anesthetized open chest dogs. The ventricular fibrillation threshold was measured by passing a gated train of 12 constant current pulses through the ventricular myocardium during the vulnerable period of the cardiac cycle. During the infusion of aminophylline, the ventricular fibrillation threshold was reduced by 30 to 40 percent of the control when pH and partial pressures of oxygen (PO2) and carbon dioxide (CO2) were kept within normal limits. When respiratory failure was produced by hypoventilation (pH 7.05 to 7.25; PC02 70 to 100 mm Hg: P02 20 to 40 mm Hg), infusion of aminophylline resulted in an even greater decrease in ventricular fibrillation threshold to 60 percent of the control level. These experiments suggest that although many factors may contribute to the increased incidence of ventricular arrhythmias in respiratory failure, pharmacologic agents, particularly aminophylline, may play a significant role.

Studies with Brugia pahangi. III: Histological changes in the affected lymph nodes of infected cats

Cats infected with Brugia pahangi by single or repeated inoculation of infective larvae for different periods of time, were autopsied and the affected lymph nodes examined histologically, stained with methyl green and pyronin Y, haematoxylin and eosin, Lendrum's eosinophil stain, Mallory's trichrome stain or the May-Grunwald Giemsa technique. In single infections, there was initially a cell-mediated type immunological response which was characterized by proliferation of mononuclear thymus-dependent cells in the paracortical region of the lymph node. The antibody-type response became more evident as the infections progressed. This response was characterized by proliferation of lymphocytes in rapidly enlarging germinal centres and the production of large numbers of plasma cells in the cortico-medullary junction and medullary cords of the nodes. In long term infections, the affected afferent lymphatic vessel and popliteal node were almost obliterated by fibrous tissue, but an inguinal lymph node complex usually developed to replace lymphatic filtration in the limb. Repeated infections produced more complicated changes. Both types of response occurred to varying degrees throughout the infection. No significant increase in mast cells or eosinophil cells was seen. Fibrous tissue increased in the lymph nodes only after long periods of infection; such nodes often became non-functional, and by-passed by new lymphatic vessels.

Tricyclic antidepressants: effects on extinction and fear learning

Rats trained to run an alley for a food reward were extinguished following injections of different antidepressants. When retested several days later, the animals extinguished following pretreatment with the NE reuptake blocker protriptyline showed faster running speeds than did the other groups. Other rats given electrical shocks following pretreatment with protriptyline avoided the compartment in which they had been shocked less than did animals shocked following pretreatment with other antidepressants. This implies an interferance with some aspect of the learning or consolidation process which is correlated with the degree of NE reuptake blockage. It is hypothesized that NE terminals are deactivated following frustrative nonreward or punishment by the conversion and reuptake of the released NE to an altered extinction molecule.

Studies with Brugia pahagi. 7. Changes in lymphatics of injected cats

Histological and gross changes in the lymphatics of cats singly or repeatedly infected with Brugia pahangi were studied chronologically over a period of 5 years. Lymphatic dilatation occurred within 2 weeks of injection and an initial acute inflammatory reaction in the lymphatic wall and lumen was followed by chronic inflammation within 4 months. In some long-term repeatedly infected cats, the lymphatics became non-functional fibrous cords and conditions of oedema and early elephantiasis, similar to those seen in early human filariasis, were produced. The main points of contention in the study of filariasis which were cluciaated in this system were: (1) that living worms cause lymphatic damage, not exacerbated by their death; (2) that lymphatic damage is not progressive after a certain peak of reaction is reached, except in repeatedly challenged animals; (3) that microfilariae do not appear to cause lymphatic damage.

Studies with Brugia pahangi. 4. Antibodies against adult and microfilarial stages

Using the indirect fluorescent antibody technique, the antibody response of cats to Brugia pahangi infections was studied using whole microfilariae and sectioned adult worms of B. pahangi as antigens. Microfilarial antigen was ineffective in detecting antibody response in cats during the microfilaraemic phase of the infection, although it was possible to detect circulating antibody in cats which became microfilaria negative after repeated and prolonged reinfection and in one cat which after infection failed to show microfilariae in its blood

Studies with Brugia pahangi. 5. Structure of the cuticle

The structure of the cuticle of third and fourth stage larvae and of adultBrugia pahangi(Nematoda: Filarioidea) was studied by light microscopy and by transmission and scanning electron microscopy. The cuticle of these worms was basically typical of the class Nematoda and consisted of cortical, matrix, and basal layers. Finely spaced annulation grooves were present and their function is discussed.

Descriptions of the cuticular ultrastructure of filarial nematodes are meagre. Studies on the cuticle of adult worms are limited to those of Kagei (1960, 1963) onSetaria cerviandLitomosoides cariniiand of McLaren and Hockley (personal communication) who examinedL. carinii and Dipetalonema vitea

The effect of metrifonate on Brugia pahangi infections in domestic cats

Metrifonate, an organophosphorus compound, caused a decline in the number of microfilariae in domestic cats experimentally infected with Brugia pahangi. It was found that the drug was active against both microfilariae and macrofilariae, but probably its greatest effect was on the macrofilarial stages. It is suggested that the drug should be used in filarial infections of man on a trial basis.

Aerobic and facultative microflora of fresh and spoiled refrigerated dough products

The microbial flora of fresh, unsterile, dough products held at refrigeration temperatures was compared with the microbial flora of the same products that had spoiled spontaneously. Various methods based on selective media were used to determine molds, yeasts, and bacteria present. Except for two special cases in which a yeast and Penicillium roqueforti induced spoilage, all of the samples deteriorated because of bacterial growth. A total of 1,132 bacterial isolates was subjected to further classification. In the spoiled products, 92% of the isolates belonged to the Lactobacillaceae. More than one-half of these (53%) belonged to the genus Lactobacillus, and an additional 36% were in the genus Leuconostoc. In the genus Leuconostoc almost all of the strains (94%) were L. mesenteroides. The third most common genus present was Streptococcus, represented by 3% of the total isolates. A preliminary taxonomic study of the microflora of refrigerated dough products revealed none of the isolates to be indicators of fecal contamination and none to be forms known to produce toxins. The highest counts encountered in the moist, fresh products were up to 200 million lactic acid bacteria per g in buttermilk biscuits, with a psychrophilic count as high as 4.8 million. In the spoiled samples, the highest total counts were 820 million in buttermilk biscuits. Mold counts were no higher than 1,800, except in the sample ruined by P. roqueforti where the count was 130,000 mold colonies.