A highly purified suspension of rabbit proximal tubules was cultured in a hormone-supplemented serum-free medium. This primary culture yielded a homogeneous population of cells that demonstrated functional and morphological polarity in mono-layers. The characteristics of the Na-dependent glucose transporter in the luminal membrane were studied by measuring the uptake of alpha-methylglucoside (AMG). The kinetics of Na-dependent AMG uptake were consistent with a single saturable system with an apparent Km of 0.8 mM and Jmax of 0.14 nmol X mg-1 X min-1. AMG permeability was 0.10 microliter X mg-1 X min-1. Uptake was inhibited 95% by 0.1 mM phlorizin and by removal of sodium. The stoichiometry of Na/glucose interaction with the carrier was 2:1. These characteristics are typical of the characteristics described for the late proximal tubule. To examine whether the glucose that enters the cell across the luminal membrane is incorporated into the metabolic pool of the cell, we studied the oxidation of [14C]glucose to 14CO2 in the absence and presence of phlorizin. Significant decarboxylation of [1-14C]glucose and [6-14C]glucose was observed, consistent with the existence of aerobic metabolism and a hexose monophosphate shunt. In the presence of 0.1 mM phlorizin, uptake and oxidation of D-glucose were inhibited to an identical degree, suggesting that luminal uptake is a rate-limiting step in the oxidation of glucose by these proximal tubular cells. These studies indicate that proximal tubular cells in primary culture utilize glucose as an energy source and that the glucose derived from transport across the luminal membrane is incorporated into the metabolic pool of the cell.

Objectives:To report the prevalence and types of biopsied oral and maxillofacial lesions (OMLs) in South-Western (Jazan Province) region, Kingdom of Saudi Arabia (KSA).Methods:This retrospective study was based on the retrieval of clinicopathological data for a period of 6 years between January 2009 and December 2014. These data were obtained between October 2014 and June 2015 from the histopathology records of King Fahad Central Hospital, Jazan, KSA, which is the only referral center for biopsy services.Results:Out of the 32149 biopsies received, 714 (2.2%) were OMLs. The age ranged from 0 (neonatal) to 100 years, with a mean age of 46.8±23.4 and a male-to-female ratio of 1:1.3. The tongue was the most common site for OMLs and for malignant neoplasms, in particular. The most common category was malignant neoplasm (38.7%), followed by inflammatory lesions (16.5%). Oral malignancies accounted for 15.8% of all malignancies. Oral squamous cell carcinoma (OSCC) (36.1%) was the most frequent type, followed by pyogenic granuloma and mucocele (7% each). Shammah-associated OSCC and epithelial dysplasia were twice as common in females.Conclusion:The number of non-malignant OMLs was much lower than expected in comparison to oral malignancies. This difference can likely be explained by the fact that the biopsies were taken only when malignancy was suspected. The higher rate of OSCC reported from this region is attributed to shammah usage. This study emphasizes the importance of biopsy services for all OMLs and the prevention of shammah use.

The characteristics of the proximal tubular Na+-H+ antiporter were determined in isolated proximal tubular cells to ascertain whether the features of this transport system in intact cells are comparable with those previously described for isolated brush-border membrane vesicles. A method is described for the rapid isolation of a purified preparation of cells that demonstrate morphological and functional characteristics of the renal proximal tubule. The cells maintain their polarity while in suspension, and adenylate cyclase activity is enhanced by parathyroid hormone but not by arginine vasopressin. The cells display gluconeogenic function and Na+-dependent alpha-methyl-D-glucose and organic phosphate cotransport, processes that confirm their proximal tubule origin. O2 consumption rates and cytosolic adenosine triphosphate levels indicate functional integrity. Na+-H+ antiport activity was defined in these cells by measuring amiloride-sensitive Na+ uptake. At intracellular pH = 6.4 vs. extracellular pH = 7.4, KtNa was 10.1 +/- 2.8 mM, and maximal sodium flux was 0.89 +/- 0.13 nmol X 10(6) cells-1 X K0.5 for amiloride and ethyl-isopropyl amiloride, measured at an external Na+ concentration of 1 mM, was observed at 2.5 X 10(-5) M and 2.9 X 10(-6) M, respectively. The external and internal loci of the exchanger displayed asymmetric affinity for the hydrogen ion: the apparent pK for the external site was 7.20-7.26 vs. less than 6.5 for the internal site. The internal site demonstrated features of positive cooperativity. In summary, the Na+-H+ antiporter present in the luminal membrane of the renal proximal tubule has been characterized in the intact cell and displays functional and kinetic parameters closely resembling those described in isolated brush-border membrane vesicles.

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