Recent studies on the reproductive biology of the schistosomes and their relevance to speciation in the Digenea

The members of the family Schistosomatidae, dioecious Digenea, are discussed with regard to their distribution, intermediate and definitive host-parasite relationships. The biological species concept is considered together with the difficulties of its application to Schistosoma spp. and the Digenea. The correlation between pairing of adult schistosomes, physical and sexual development and the maintenance of reproductive potential is emphasised. Development of the female reproductive system does not depend upon species-specific pairing. In some combinations, e.g., Schistosoma haematobium/Schistosoma intercalatum and Schistosoma bovis/Schistosoma curassoni, a specific mate choice system apparently does not exist, whereas it does in other combinations, e.g., Schistosoma mansoni/Schistosoma intercalatum. In mixed infections change of mate may occur and when the opportunity arises heterospecific pairs of worms will change partners to conspecific pairs. Interspecific pairing in adult schistosomes will lead to either hybridisation or parthenogenesis. Yet the majority of schistosomes that inhabit the same definitive host maintain their genetic identity: specific mate recognition, site selection within the host and heterologous immunity have been suggested as isolating mechanisms. Experimental intraspecific crosses have enabled evaluation of the degree to which some populations separated and became reproductively isolated through pre-mating isolating mechanisms, indicative of incipient speciation, e.g., the Lower Guinea and Zaire strains of S. intercalatum. The occurrence and significance of parthenogenesis in schistosomes and other species of Digenea are discussed. The consequences of interspecific mating interactions in schistosomes with regard to parasite epidemiology, interspecific competition and genetic heterogeneity are debated. Geographical isolation and host specificity represent important pre-zygotic isolating mechanisms. It is suggested that site selection within the host and heterologous immunity may both reduce interspecific genetic interchange when digenean parasites utilise the same definitive host.     

A survey of 4478 biopsy specimens of oral lesions

A surgery of 4478 biopsy specimens in dental institute in India was carried out to compare and correlate results obtained from such studies carried out elsewhere. The study revealed that there are more than 150 common and rare oral diseases which are diagnosed and treated by dentists. 13 common diseases comprised majority (60.37%) of the biopsy specimens studied. Of these, tumors (25.53%) and Cysts (14.38%) constituted the majority of the bulk. The study also shows that most of the benign tumors were mesenchymal in origin (almost 5.5:1) while malignant tumors were epithelial (almost 20:1) in origin. Cystic lesions included the most common radicular cyst (7.12%) and the rare hydatid cyst (one case reported). Gingival hyperplasia mainly due to local aetiology, constituted the 3rd largest group. The purpose of this report is to provide some information about the type and frequency of oral lesions usually diagnosed, with the help of histopathological examination in India.     

Clinical picture of gonadal dysgenesis in the children's and adolescents' consulting hours

Report on 34 patients with gonodal dysgenesis and chromosomal aberrations ranging in age from 4 to 28 years. The observation time amount to five years on the average. 23 urological examinations revealed 12 kidney malformations (=52,2 percent). Special pathological x-ray findings on hands and writs were significantly more frequent in Turner's disease than in normal population. In T.S. the average value of conspicicous dactyloscopic findings was about 3,0 patient, (in family members it was 0,9 test person). In the most of all cases the psychological examination resulted in dependence and less of contact. Sexuell inclinations are denied. The hormonal substitution was carried out with "Mestranol" or with "Sequenz-Ovosiston".     

GALVANOMAGNETIC PROPERTIES OF METALS AT BOILING OF LIQUID HELIUM

1.IntroductionTheproblemofheatgenerationduet0J0uleenergydissipationexistsatlowtemper-aturegalvan0magneticmeasuremeflts.Especiallythispr0blemisactualathighcurrentdensityandlargeresistivity.Thephenomena0ftemperaturechargeandheattransferinmetaJsareknownt0bedeterminedmainlybyanelectr0nsysteminacc0rdancewithitsdispersionlawandscatteringmechanisms-Usuallyaheateliminationregime0fasampleisnotsimpleandis0tr0picbecausespecimensareplacedinliquid'heliumcavitywithhelpoflowtemperatureinsetwhereasampleism0u…     

Oral teratoma (epignathus) with intracranial extension: a report of two cases

Epignathi are unusual congenital tumours presenting as oropharyngeal masses, often resulting in rapid asphyxia following birth. Occasionally, intracranial extension of the tumour is present, and two such cases are described. The presence of this complication, diagnosable by ultrasound examination, indicates that aggressive surgical treatment is inappropriate.     

Twenty-four-hour L-[1-(13)C]tyrosine and L-[3,3-(2)H2]phenylalanine oral tracer studies at generous, intermediate, and low phenylalanine intakes to estimate aromatic amino acid requirements in adults

Daily pattern and rates of whole-body tyrosine oxidation and phenylalanine hydroxylation were determined in young adults (15 men, 1 woman) receiving [13C]tyrosine and [(2)H2]phenylalanine via primed, constant oral infusion and [(2)H4]tyrosine by vein (five subjects also received [(2)H3]leucine simultaneously by vein) continuously for 24 h (12 h fast then 12 h fed). Subjects were given a diet supplying 96.6 (n = 5), 35.6 (the proposed requirement; n = 5), and 18.5 mg phenylalanine x kg(-1) x d(-1) (n = 6) based on an otherwise adequate L-amino acid mixture for 6 d before the 24-h tracer study began. [Each diet was low in tyrosine: 6.79 mg x kg(-1) x d(-1).] Our hypothesis was that subjects would be in tyrosine equilibrium, positive balance, or both, at the 96.6- and 35.6-mg intakes and in distinctly negative balance at the 18.5-mg intake. The diurnal pattern in phenylalanine and tyrosine kinetics was dependent on the intake and, presumably, on the adequacy of dietary phenylalanine. Wholebody tyrosine balances, determined from rates of phenylalanine hydroxylation and tyrosine input and oxidation were negative (0.05 < P < 0.1 from zero balance) with the low (18.5 mg) phenylalanine intake [total aromatic amino acid (AAA) intake: 25.3 mg x kg(-1) x d(-1)] but at equilibrium (P > 0.05 from zero balance) with the two higher phenylalanine intakes. Whole-body AAA balance (AAA intake - tyrosine oxidation) was negative (P < 0.05 from zero balance) with the low intake, at equilibrium with the intermediate intake, and apparently distinctly positive (P < 0.05) with the generous intake. Despite model limitations, as discussed, these findings lend further support for a proposed, tentative value for a total mean requirement of 39 mg AAA x kg(-1) x d(-1).     

Focal areas of increased renal tracer uptake on bone scans can mimic metastases in the lower ribs

Focal renal concentration of radioactivity can simulate metastatic deposits in the lower ribs on bone scintigrams. 400 consecutive bone scintigrams were reviewed for focal areas of increased tracer activity in the kidneys. 62 patients (15.5%) had at least one renal hot spot. In 42 of these 62 patients (67.7%) there was an increased focal uptake in the left kidney (18 upper pole, 18 middle pole and six lower pole). 50 out of 62 bone scans (80.7%) showed increased activity in the right kidney (14 upper pole, 32 middle pole and four lower pole). With the incidence of focal areas of activity in the upper poles of the kidneys being 8%, the interpretation of a single focal abnormality projected over the lower ribs should be made with particular care, especially in cancer patients.