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Biomedical subjects

J H Bryan

Publications and source records attributed to J H Bryan.

At least 55 records · Page 3Linked to original sources
PubMed1983

The immotile cilia syndrome. Mice versus man.

When homozygous the recessive, pleiotropic, mutation hpy (hydrocephalic-polydactyl) produces post-natal hydrocephalus, complete sterility in males, and reduced reproductive performance in females. Because the fertility problems and the development of hydrocephalus could arise as consequences of defective flagella and ciliary axonemes, this mutant type might serve as a useful animal model for the immotile cilia syndrome. Ultrastructural defects seen in axonemes of flagella, and of cilia from the trachea, oviduct, and ependyma included: a deficiency of inner dynein arms (the most frequent defect); an absence of one or both central-pair tubules; extra central tubules; a displacement of one outer doublet and/or the central-pair tubules. Some axonemes showed more than one of these defects. The frequency of dynein-deficient axonemes in all three tissues was similar (about 35%) and fell within the range reported for human patients with the immotile cilia syndrome. On this basis, this mutant type might be considered as a useful animal model for such studies. There were no indications of situs inversus, nor was there a marked increase in respiratory problems. So hpy/hpy mice do not exhibit all of the clinical symptoms characteristic of the human condition.

Animals↗
PubMed1983

Abnormal cilia in a male-sterile mutant mouse.

In mice homozygous for the mutation hydrocephalic-polydactyl (hpy) ciliary axonemes from tracheal, oviducal, and ependymal lining cells showed a variety of abnormalities. Defects included: a deficiency of inner dynein arms, extra central tubules, a displacement of one outer doublet and/or the central tubules, and double axonemes. More than one kind of defect was seen in some axonemes. None of the types of defects observed in mutants were encountered in equivalent samples from non-mutant littermates. Except for the most common defect, the deficiency in dynein arms, which occurred to about the same extent (approximately 34%) in all three tissues, there were marked variations in frequency among the tissue types with respect to the other defects. In general, defects such as central tubule anomalies, displaced tubules, and double axonemes occurred with the highest frequencies in axonemes from tracheal epithelial cells and with the lowest frequencies in samples of oviducal epithelium. Fused cilia were seen only in ependymal cell samples. Some of the defects encountered were common to sperm flagella axonemes while others appeared restricted to somatic tissues, suggesting, perhaps, each tissue type may exert its own modulating influence on the expression of the mutant gene.

Animals↗
PubMed1983

Leishmaniasis in The Gambia. 2. A study of possible vectors and animal reservoirs, with the first report of a case of canine leishmaniasis in The Gambia.

Following the detection of two cases of leishmaniasis in The Gambia, the possible vectors and animal reservoirs were studied. A total of 5, 158 phlebotomine sandflies, in 20 species and subspecies were captured, including 98 males and 61 females of Phlebotomus duboscqi. This species is a vector of cutaneous leishmaniasis in Senegal and must be suspected as a vector in The Gambia; it was captured close to the dwellings of both patients and from rodent burrows, including those of Mastomys erythroleucus, a known reservoir of cutaneous leishmaniasis in Senegal. We report the first finding in The Gambia of visceral leishmaniasis in a dog captured near the house of the patient with visceral leishmaniasis. This strongly suggests that dogs could be a reservoir of this infection in this area. The vector was not determined.

Animals↗
PubMed1983

Anopheles gambiae and A. melas at Brefet, The Gambia, and their role in malaria transmission.

Anopheles melas and A. gambiae were studied at the village of Brefet, The Gambia. The population density of A. gambiae varied according to the rainfall. However, this was not so with A. melas, the highest densities of which occurred after the cessation of the rains. The sporozoite rate averaged 3.5% in A. gambiae but only 0.35% in A. melas. Possible causes of these differences are discussed.

Animals↗
PubMed1981

Spermatogenesis revisited. V. Spermiogenesis in mice homozygous for two different male-sterile mutations (ps and hpy).

In male mice homozygous for both ps and hpy, two recessive, pleiotrophic, mutations, gametogenesis is normal through meiosis but no functional spermatozoa are produced. Spermiogenesis is abnormal from the Golgi phase on. The types of abnormalities seen during the early and mid-stages of spermiogenesis are characteristic of those associated with the presence of the ps mutation whereas those associated with the hpy mutation appear during the later stages of spermatid development. While centriolar ultrastructure was normal, axonemal structures were only rarely encountered and no late spermatids with recognizable flagella were seen. Some late spermatids showed head abnormalities of the type characteristic of the ps mutation while others were recognizable as being of the hpy type. A released "gamete" usually consisted of a distorted nucleus and associated acrosome enclosed in a tightly fitting plasma membrane. No spermatids exhibiting a novel phenotype were encountered. The findings support the view that, despite their simultaneous presence in the double homozygote, each mutation acts autonomously. These studies also allow a similar inference to be made with respect to the extent of the interrelationship of the other major sub-processes of spermiogenesis.

Acrosome↗
PubMed1981

Congenital transfer of antibodies against malarial sporozoites detected in Gambian infants.

A survey of the antibody response to sporozoites of Plasmodium falciparum was carried out on plasma samples obtained from 20 mothers and their newborn infants living in The Gambia, West Africa. Serological assays detected antisporozoite antibodies in 90% (18/20) of the mothers, and similar titers were detected in 17/18 of their infants. The antisporozoite antibodies were gradually lost from the circulation of the babies until by approximately 6 months of age positive reactions against P. falciparum sporozoites were no longer detected. A similar pattern of acquisition and persistence of maternally-derived antisporozoite antibodies was noted in a neonatal rhesus monkey born to a female immunized with sporozoites of Plasmodium knowlesi.

Animals↗
PubMed1979

Antibodies to sporozoites: their frequent occurrence in individuals living in an area of hyperendemic malaria.

Serum samples from 158 West Africans were tested for antibodies against sporozoites, the vector stage of the malaria parasite. Antibodies specific for Plasmodium falciparum sporozoites were detected by means of the circumsporozoite precipitation assay and indirect immunofluorescence. More than 90 percent of the serum samples from adults gave positive immunofluorescent reactions against falciparum sporozoites, whereas most of the samples from children gave low or negative reactions.

Adolescent↗
PubMed1978

Acute promyelocytic leukemia presenting as a pelvic mass.

The case history of a child with acute promyelocytic leukemia (APL) is reported to illustrate both an unusual presentation of APL as a pelvic mass and to review the pathophysiology and treatment of the disease. Therapy of APL consists of chemotherapy, namely adriamycin/daunomycin for remission induction, and of control of disseminated intravascular coagulation. A chloroma, if present, may require local irradiation in addition to chemotherapy. With aggressive management, the number of prolonged remissions may be greater for APL than for any other form of acute myelogenous leukemia (AML), with significant numbers of patients achieving five-year survival.

Antineoplastic Agents↗
PubMed1978

The use of ABO blood groups as markers for mosquito biting studies.

Discrepancies between malaria inoculation rates measured entomologically and parasitologically may be explained, at least in part, if infants and children receive less mosquito bites per night than do adults. We found that this problem could be studied by choosing women and children of different ABO blood groups. In preliminary laboratory studies it was found that the blood group of a mosquito's blood meal could be determined in parous and nulliparous mosquitoes for at least 24 hours, and, nullipares up to 34 hours, after feeding. An antiserum against the O group was necessary to distinguish non A or B red cells from those of animal origin. Cross reactions did occur, presumably as a result of the digestion by mosquitoes of the red cell surfaces, but in every case the strongest and earliest developing agglutination was that of the host. Field studies were made using women and children sleeping under mosquito nets, the holes in which made the nets a trapping device. The women, on average, received over seven times more bites per night than did the children. The migration of blood-fed mosquitoes from one net to another was negligible.

ABO Blood-Group System↗
PubMed1978

The lethal effects of the cibarial and pharyngeal armatures of mosquitoes on microfilariae.

Microfilariae of Wuchereria bancrofti and Brugia pahangi were killed by the chewing action of the cibarial and pharyngeal armatures and other papillae and spines in the fore-gut of mosquitoes. The proportion of ingested microfilariae that were killed was largely dependent on the presence and shape of the cibarial armature. Anopheles farauti No. 1 and Anopheles gambiae species A and B have well developed cibarial armatures and killed 36 to 96% of the ingested microfilariae. Culex pipiens fatigans has a poorly developed cibarial armature and killed only 6% of the microfilariae. Aedes aegypti and Aedes togoi lack cibarial armatures but have the remaining fore-gut structures. They killed only 2 to 22% of the microfilariae. The significance of these observations in relation to the control of filariasis with diethylcarbamazine is discussed.

Animals↗
PubMed1977

Brain development in hydrocephalic-polydactyl, a recessive pleiotropic mutant in the mouse.

Animals homozygous for the recessive, pleiotropic, mutation hpy (hydrocephalic-polydactyl) progressively lag behind their wild-type litter-mates in increase in body weight and brain dry weight over the period from 1-40 days post-partum; many homozygotes die within the first 14 days after birth. Light microscope observations of serial sections of brains revealed a mild to severe dilation of the entire ventricular system and damaged ependyma. Ciliated ependymal cells appeared reduced in number and destruction of ependymal cells over wide areas of the ventricular surfaces was observed. Preliminary scanning electron microscope studies confirmed the light microscope observations and revealed large numbers of erythrocytes and phagocytes associated with the ependymal surface. Neither the histological studies nor experiments involving intracerebral injections of tracer dyes demonstrated obstruction or stenosis of the aqueduct of Sylvius. Individual neurons appeared to be present in normal numbers and to be developing normally and at the same rate as in wild-type animals.

Animals↗