Evaluation of maxillary sinus dimensions in gender determination using helical CT scanning.

Gender determination is an important step in identification in forensic medicine. CT measurements of maxillary sinuses may be useful to support gender identification. This study was undertaken to study the accuracy and reliability of maxillary sinus dimensions measurement in gender classification through the use of reconstructed helical CT images. Eighty-eight patients (43 men and 45 women) with age range from 20 to 49 years were selected in this study. The width, length, and height of the maxillary sinuses in addition to the total distance across both sinuses were measured. Data were subjected to discriminant analysis for gender using multiple regression analysis. Maxillary sinus height was the best discriminant parameter that could be used to study sexual dimorphism with an overall accuracy of 71.6%. Using multivariate analysis, 74.4% of male sinuses and 73.3% of female sinuses were sexed correctly. The overall percentage for sexing maxillary sinuses correctly was 73.9%. It can be concluded that reconstructed CT image can provide valuable measurements for maxillary sinuses and could be used for sexing when other methods of sexing are not conclusive.

Functional studies of a chimeric protein containing portions of the Na(+)/glucose and Na(+)/myo-inositol cotransporters.

We obtained cDNA chimeras between Na/glucose cotransporter (SGLT1) and the homologous Na(+)/myo-inositol cotransporter (SMIT) by creating random chimeras in plasmids. Of 12 chimeras, two were functional when expressed in Xenopus laevis oocytes but, upon sequencing, only one of them (C1) produced an actual chimeric protein. In C1, the first 69 amino acids of SGLT1 were replaced by the corresponding 50 amino acids of SMIT. C1 transports the same sugars as does SGLT1. C1's affinity for all sugar substrates was systematically increased by a factor of 3.3+/-0.4 but the V(max) was diminished by a factor of 15-40. In contrast, the cotransport affinity for Na(+) was unchanged. The surface expression of C1 was one seventh that of SGLT1, which explains part of the reduced V(max) and implies a significant reduction in turnover rate. N-terminal truncated constructs of SGLT1 cDNA showed that deleting amino acids 2-14 does not affect cotransporter activity, but that the pentapeptide T(14)RPVET(19) is important for normal levels of SGLT1 current. The main result of a kinetic analysis of the systematic increase in apparent affinity for sugars, together with the intact Na apparent affinity, suggests enhanced access to the sugar binding site in C1.

Serum retinol concentrations in children are affected by food sources of beta-carotene, fat intake, and anthelmintic drug treatment.

The provision of vitamin A in food sources of beta-carotene is an alternative to the distribution of high-dose capsules. To examine factors that may influence the success of food-based programs, a study was carried out in Sumatra, Indonesia, of the effect of food sources of beta-carotene, extra dietary fat, and Ascaris lumbricoides infection on serum retinol concentrations in children. Meals and snacks with various amounts of beta-carotene and fat were fed at midday to children 3-6 y of age for 3 wk. Some groups of children were dewormed with the anthelmintic levamisole before the feeding period, whereas others remained infected. Results showed that the incorporation of beta-carotene sources (mainly in the form of red sweet potatoes) into the meal significantly increased serum retinol concentrations. The greatest rise in serum retinol occurred when meals contained added beta-carotene sources and added fat and the children were dewormed. Adding more fat to the meal and deworming the children caused a rise in serum retinol similar to that seen when feeding additional beta-carotene sources. Moreover, the effects of fat and deworming together were additive to the effects of additional beta-carotene sources. When the meal contained additional beta-carotene sources, added fat caused a further improvement in serum retinol concentrations but only if A. lumbricoides infection was low. These studies indicated that food-based interventions in vitamin A-deficient areas might be successful and that other interventions such as increasing dietary fat concentrations and anthelmintic treatment should be considered along with increasing consumption of beta-carotene-rich food.

Sodium leak pathway and substrate binding order in the Na+-glucose cotransporter.

The Na+-glucose cotransporter (SGLT1) expressed in Xenopus laevis oocytes was shown to generate a phlorizin-sensitive sodium leak in the absence of sugars. Using the current model for SGLT1, where the sodium leak was presumed to occur after two sodium ions are bound to the free carrier before glucose binding, a characteristic concentration constant (Kc) was introduced to describe the relative importance of the sodium leak versus Na+-glucose cotransport currents. Kc represents the glucose concentration at which the Na+-glucose cotransport current is equal to the sodium leak. As both the sodium leak and the Na+-glucose cotransport current are predicted to occur after the binding of two sodium ions, the model predicted that Kc should be sodium-independent. However, by using a two-microelectrode voltage-clamp technique, the observed Kc was shown to depend strongly on the external sodium concentration ([Na+]o): it was four times higher at 5 mM [Na+]o than at 20 mM [Na+]o. In addition, the magnitude of the sodium leak varied as a function of [Na+]o in a Michaelian fashion, and the sodium affinity constant for the sodium leak was 2-4 times lower than that for cotransport in the presence of low external glucose concentrations (50 or 100 microM), whereas the current model predicted a sigmoidal sodium dependence of the sodium leak and identical sodium affinities for the sodium leak and the Na+-glucose cotransport. These observations indicate that the sodium leak occurs after one sodium ion is associated with the carrier and agree with predictions from a model with the binding order sodium-glucose-sodium. This conclusion was also supported by experiments performed where protons replaced Na+ as a "driving cation."

Electrogenic amino acid exchange via the rBAT transporter.

A cDNA clone was isolated from rabbit renal cortex using DNA-mediated expression cloning, which caused alanine-dependent outward currents when expressed in Xenopus oocytes. The cDNA encodes rBAT, a Na-independent amino acid transporter previously cloned elsewhere. Exposure of cDNA-injected oocytes to neutral amino acids led to voltage-dependent outward currents, but inward currents were seen upon exposure to basic amino acids. Assuming one charge/alanine, the outward current represented 38% of the rate of uptake of radiolabelled alanine, and was significantly reduced by prolonged preincubation of oocytes in 5 mM alanine. The currents were shown to be due to countertransport of basic amino acids for external amino acids using the cut-open oocyte system. This transport represents a major mode of action of this protein, and may help in defining a physiological role for rBAT in the apical membrane of renal and intestinal cells.

Biosynthesis and polarized distribution of neutral endopeptidase in primary cultures of kidney proximal tubule cells.

When cultured in defined medium, kidney proximal convoluted tubule (PCT) cells form a homogeneous population and retain a number of differentiated functions. To characterize this cell system further as a functional model of epithelial polarity, we investigated the biogenic pathway of neutral endopeptidase (NEP), one of the most abundant microvillar membrane proteins in intestinal and kidney cells. We showed that, in contrast with some tumoral cell lines, RNA extracted from PCT cells shows the presence of a single mRNA species encoding NEP. Pulse-chase studies followed by selective immunoprecipitation of NEP molecules present either at the cell surface or in intracellular cell compartments showed that newly synthesized NEP molecules reached the cell surface as early as 30 min after the beginning of the chase with maximum cell surface expression at 60 min. When grown on semipermeable supports, PCT cells were found to target NEP exclusively to the apical plasma membrane. Similar results have been described using MDCK cells to study targeting of recombinant NEP. Thus primary cultures of PCT cells represent a new model with which to investigate the biogenic pathway of endogenous proteins in native epithelial cells.

HIV and AIDS in Indonesia.

PIP: Indonesia is the fourth most populous nation in the world, with a population of 184 million in 1993. By the end of December 1993, the Ministry of Health had reported 193 confirmed HIV infections. There have been 34 deaths from AIDS and HIV infections have been reported from 11 of the 27 provinces in the country. Where nationality is known, native Indonesians comprise 51% of HIV infections and non-Indonesians the remaining 49%. Sexual transmission accounts for 96% of cases where the route of transmission is known; route is unknown in 54 cases. Male:female sex ratio is 23:1 for reported AIDS cases and 4:1 for HIV infections for which sex is known. There have been no pediatric cases reported and 96% of those infected for whom age is known are 15-49 years. The present reporting system definitely underestimates the actual number of HIV infections. The window of prevention in the linear growth phase of the epidemic closed in 1992, when Indonesia began to experience exponential epidemic growth. Although the epidemiologic situation is worsening rapidly, a chance remains that HIV can be kept from becoming a major development problem. The government is now addressing the epidemic as a developmental issue, calling for action across sectors and in partnership with nongovernmental organizations and the private sector much earlier than elsewhere. The successful family planning program instituted in response to the population crisis will serve as a model for HIV prevention strategies and programs in Indonesia.^ieng

Polarized distribution of neutral endopeptidase 24.11 at the cell surface of cultured human intestinal epithelial Caco-2 cells.

The human colon cancer cell line Caco-2 undergoes spontaneous enterocytic differentiation during growth, and expresses a number of brush-border-membrane-associated hydrolases typical of a differentiated phenotype. Among these are alkaline phosphatase, dipeptidyl peptidase IV and sucrase-isomaltase (sucrase, EC 3.2.1.48). Neutral endopeptidase 24.11 [EC 3.4.24.11, neprilysin (NEP)] is another abundant protease of normal enterocytes but its presence in Caco-2 cells has not been fully documented yet. In this paper, we show that Caco-2 cell extracts hydrolyse tritiated [D-Ala2Leu5]enkephalin with a Km of 180 microM, very close to the value obtained for the NEP present in the rabbit kidney (118 microM). Western-blot analysis of brush-border membranes purified from post-confluent cells revealed a protein with an apparent molecular mass of 94000 Da similar to that of the rabbit kidney NEP. The amount of enzyme in cell extracts increased as a function of the age of the culture, indicating that NEP expression is correlated with the degree of cell differentiation as is also the case for sucrase and dipeptidylpeptidase IV (DPP-IV). Binding of a radiolabelled antibody to Caco-2 cell monolayers grown on semi-permeable filters indicated that 95% of NEP molecules present at the cell surface are on the apical side. Immunocytochemical and flow cytometric analysis of intact and permeabilized cells were also used to investigate the presence of NEP and DPP-IV at the surface of Caco-2 cells. Whereas DPP-IV staining appeared to be homogeneous throughout the entire cell population, NEP-related fluorescence exhibited a bimodal distribution which indicates an uneven expression of the protein at the cell surface. Permeabilization of monolayers with saponin before staining restored a labelling pattern for NEP similar to the one obtained for DPP-IV. This suggests that although DPP-IV and NEP follow similar patterns of expression when enzymic activities are measured on whole-cell extracts, targeting of these brush-border proteins to the cell surface appears to be regulated in different ways.

Increased functional differentiation of rabbit proximal tubule cells cultured in glucose-free media.

We have determined the influence of glucose (Glc)-free medium on the growth and differentiation of rabbit kidney proximal tubule cells (PTC) in primary cultures. The specific growth rates and the protein-to-volume ratios are shown to be independent of the culture conditions. In contrast, the functional expression of four brush-border membrane enzyme markers was found to decline steadily and in the same way from day 3 in culture up to late confluence in Glc-containing medium, and different evolution patterns and high expression levels were observed up to confluence in a Glc-free glutamine (Gln)-supplemented medium. Electron microscopy clearly showed, however, that the functional and morphological differentiation of the brush-border membrane is not correlated. Finally, by use of an indirect immunofluorescent technique in combination with flow cytometry, it is demonstrated that confluent cells grown in Glc and Gln media form homogeneous cell populations of PTC. It is thus concluded that the functional differentiation of rabbit kidney PTC in primary cultures is strongly dependent upon the energy source present in the culture medium.

Neutral endopeptidase, a major brush border protein of the kidney proximal nephron, is directly targeted to the apical domain when expressed in Madin-Darby canine kidney cells.

We have used a retroviral vector containing both the cDNA for rabbit neutral endopeptidase (EC 3.4.24.11; NEP) and the neomycin resistance gene to promote the expression of NEP in a polarized Madin-Darby canine kidney (MDCK) cell line. Cells resistant to G418 (a neomycin synthetic analog) were analyzed with a fluorescence-activated cell sorter to isolate a homogeneous population of cells which stably expressed NEP at their surface. When cells grown in Petri dishes were labeled with an antibody to NEP coupled to colloidal gold and examined under the electron microscope, a strong labeling of microvilli was observed, whereas very few particles were present on the basolateral domain, suggesting that the polarized distribution of this enzyme typical of proximal tubule cells is maintained in this MDCK cell population. To study more accurately the mechanism by which MDCK cells target NEP to the apical surface, cultures were grown to confluence on Costar Transwell chambers and used for pulse-chase experiments with [35S]methionine. Immunoprecipitation of recombinant NEP was then performed by adding an anti-NEP polyclonal antibody to the apical or basolateral surface of intact monolayers and by analyzing immunoprecipitates by gel electrophoresis and fluorography. Our results suggest that NEP is delivered directly to the apical domain and does not transit through the basolateral domain of the plasma membrane. This NEP-expressing MDCK cell line therefore constitutes a new model for investigating the molecular basis of apical membrane targeting in polarized epithelial cells.

Interactions between vitamin A deficiency and Plasmodium berghei infection in the rat.

It has been claimed that vitamin A deficiency increases the severity of malarial infection in rats. We measured parasitemia, mortality, serum retinol, liver retinol, spleen weight, and degree of xerophthalmia in vitamin A-deficient rats (A-), pair-fed control rats (A+PF), and ad libitum-fed control rats (A+AL) infected with Plasmodium berghei, a rodent malarial parasite. In experiments 1 and 2 vitamin A deprivation began at weaning. Parasitemia and mortality among mildly deficient (expt. 1, mean serum retinol 19 micrograms/dl) or acutely deficient rats (expt. 2, mean serum retinol less than 5 micrograms/dl) infected with P. berghei were not significantly different from those of infected A+AL or A+PF rats. Furthermore, when the mildly deficient rats were given a second, larger dose of P. berghei, all demonstrated complete immunity to the parasite. However, when vitamin A was withdrawn midway through pregnancy (expt. 3), the A- rats experienced significantly higher parasitemia and mortality during infection with P. berghei. Malaria caused a significant decrease in the serum retinol but not liver retinol of the A+PF and A+AL rats. Among the acutely deficient rats, xerophthalmia was significantly more prevalent and more severe among those infected with malaria than among those not infected with malaria. Malaria and vitamin A deficiency acted synergistically to increase spleen weight, and this interaction was highly significant. In these experiments, vitamin A deficiency decreased the rats' ability to recover from malaria, but only when the deficiency began early in life, was very severe, and the rats were young when infected.(ABSTRACT TRUNCATED AT 250 WORDS)