Multiple mutations in a specific gene in a small population

Hereditary diseases have been reported with relatively high frequency in some small populations. Founder effect and genetic drift, associated or not with selective advantage of heterozygotes in case of recessive diseases, are the main explanations. Therefore, if we consider one population and one particular disease, only one deleterious allele should be observed. Determination of mutations has shown that in most cases the situation is more complex; more than one mutation is found among the patients. This finding can be explained by a multiple founder effect, with genetic drift and new mutations.     

Aspiration of a primary tooth in a patient with a tracheostomy

We report a clinical case of a patient affected by splenic non-Hodgkin lymphoma and virus C hepatitis. It seems that this kind of association is original because as far as we know the association between non-Hodgkin lymphoma and HCV did not include non-Hodgkin lymphoma involving the spleen. Indeed, in our patient, there was an increase of CD/57 lymphocytes. In our opinion this could be interesting in the disorders of the immune system associated with lymphoma.     

Syphilis in pregnancy: a medical audit in a rural district

A medical audit was performed in Umzingwane District, Zimbabwe, to assess the quality of antenatal care in 1991 regarding detection and management of syphilis. Two thousand one hundred and sixty one women booked for antenatal care, 1433 (66 pc) received a RPR test result, 197 (14 pc) tests were positive. In 32 (16 pc) of the 197 RPR positive women the outcome of the pregnancy could not be established. Of 165 women 111 (67 pc) received adequate treatment for syphilis. A perinatal mortality rate (PNMR) of 173/1,000 was associated with inadequately or not treated RPR positive mothers and a PNMR of 21/1,000 with RPR negative and untested mothers (odd's ratio = 9.9; 95 pc confidence interval 3.8-24.9, p < 0.001). It is estimated that only 42 pc of all pregnant women and 24 pc of the couples with syphilis in 1991 were treated adequately. Recommendations are made to improve the quality of surveillance of syphilis in pregnancy in a rural district.     

Nerve regeneration in a 'pseudo-nerve' graft created in a silicone tube

The pseudo-nerve, which contains longitudinal Schwann cell columns without axons and surrounded by perineurium-like tissue but no axons (Q. Zhao, L.B. Dahlin, M. Kanje, G. Lundborg, Brain Res. 592 (1992) 106-114), was applied as a graft to repair nerve defect in rats. Creation of the pseudo-nerve was accomplished by inserting the proximal and distal stumps of a cut sciatic nerve into a silicone tube. The proximal insert was cut far proximally to prevent axons from entering the tube. After 4 weeks, the pseudo-nerve was harvested, trimmed into a 10-mm long graft and transplanted into a corresponding defect of the contralateral sciatic nerve. Nerve regeneration through the pseudo-nerve was examined by pinch reflex test and neurofilament staining after 6 days or by morphology after 4, 6 or 8 weeks. The results showed that the pseudo-nerve could induce nerve regeneration to a similar extend as a real nerve graft. The neurobiological composition of the pseudo-nerve and the factors influencing its formation were also studied. By double staining of S-100 and laminin we found that the longitudinally organized Schwann cell columns in the pseudo-nerve were surrounded by basal laminae and ensheathed by a layer of vascularized perineurium-like tissue. Macrophages (ED1 and ED2) and their products interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) were constantly present in the pseudo-nerve. Besides, the size of tube was a crucial factor in influencing pseudo-nerve formation, e.g. a thicker pseudo-nerve was formed in tubes with larger diameters or shorter gap lengths. No pseudo-nerve was formed when the gap was 15 mm long. When both proximal and distal inserts were isolated nerve segments the pseudo-nerve was still formed but thin, probably because of compromised vascular supply. Taken together, the results suggested that the pseudo-nerve contains the essential neurobiological elements to induce successful axonal elongation.     

Consolidation of a porous material in hot pressing in a closed mold fitted with a compensator

A method has been developed for calculating the compaction of a porous material in hot pressing in a closed mold fitted with a compensation slot. Simulation is reported for various initial porosities and compensating slot heights. The results from pressing in a closed mold with compensator and in an open mold are compared. Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5–6, pp. 14–18, May–June, 1998.     

Distribution of metal particles in a slag during argon blowing of a melt in a ladle

The distribution of metal particles in a slag is studied during argon blowing of steel in a ladle. It is established that the fraction of the metallic phase in the top slag layer is 3.5–5 times smaller than that in the middle and bottom layers. A microscopic analysis of the fraction composition and the geometric shape of the metallic particles show that all portions of the slag part of samples contain significantly larger amounts (by a factor of approximately 4–5) of irregular plane particles along with fine spherical particles.