Ionic conductivity, transference numbers, composition and mobility of ions in cross-linked lysozyme crystals

Basic fibroblast growth factor (bFGF) gene expression as well as its immunoreactivity were studied after partial unilateral hemitransection of the rat brain during a time course of 24 h, 72 h, 7 and 14 days. The mechanical injury resulted in a global increase of bFGF gene expression at the 24-h time interval. This global increase was seen at the ipsilateral site at the level of the lesion as well as rostral to the lesion in the ipsilateral hemisphere. The upregulation in bFGF gene expression was in most of the areas investigated due to an upregulation in glial cells as seen by means of nonradioactive in situ hybridization compared with immunocytochemistry for glial fibrillary acidic protein (GFAP). Basic FGF immunoreactivity (IR) was increased around the lesion in glial cell nuclei 7 days after the injury. This increase was also detected in GFAP positive glial cells surrounding small vessels in the lesioned area. Moreover, in the present paper we demonstrate increased tenascin immunoreactivity in the lesioned area 7 days after injury. The tenascin IR was increased at the edges of the lesion as well as in vessel like structures. The tenascin IR was partially codistributed with GFAP IR in the lesioned area. The lesion was also characterized by an increase in vimentin IR as well as in laminin IR. It is suggested that the observed changes in the expression of bFGF, matrix proteins (laminin, tenascin) and intermediate filaments (vimentin) are involved in (a) tissue repair, (b) protection of neuronal cells from excitotoxic influences and (c) formation of new vessels in the lesioned area.     

Absorption and intestinal metabolism of purine dideoxynucleosides and an adenosine deaminase-activated prodrug of 2',3'-dideoxyinosine in the mesenteric vein cannulated rat ileum

This study investigates the mechanisms of absorption and the role of intestinally localized purine salvage pathway enzymes on the ileal availabilities of 2',3'-dideoxyinosine (ddI), a substrate for purine nucleoside phosphorylase (PNP); 2'-fluoro-2',3'-dideoxyinosine (F-ddI), a non-PNP substrate; and 6-chloro-2',3'-dideoxypurine (6-Cl-ddP), an adenosine deaminase (ADA) activated prodrug of ddI. The potential for increasing the intestinal availability of 6-Cl-ddP through the use of ADA inhibitors, namely, 2'-deoxycoformycin (DCF) and erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), is also explored. Drug permeability coefficients across the intestinal epithelium were determined in in situ perfusions in the mesenteric vein cannulated rat ileum based on both drug appearance in blood (Pblood) and disappearance from the lumen (Plumen) and their paracellular and transcellular components were estimated by comparison to the permeabilities of two paracellular markers, mannitol and urea. Values of Pblood for ddI were determined to be (1.1 +/- 0.3) x 10(-6) cm/s, in close agreement with the value of (1.0 +/- 0.3) x 10(-6) cm/s obtained for F-ddI, a PNP resistant analogue of ddI having virtually the same molecular size and lipophilicity as ddI. This indicates that PNP may not play an important role in the low intestinal absorption of ddI. The Pblood for 6-Cl-ddP, (19 +/- 2) x 10(-6) cm/s, was 4.5-fold lower than Plumen, (84 +/- 12) x 10(-6) cm/s, which means that 77 +/- 6% of 6-Cl-ddP was metabolized during its intestinal transport, thus qualitatively accounting for the low oral bioavailability (7%) of 6-Cl-ddP observed in vivo in rats. Extensive intracellular metabolism of 6-Cl-ddP by ADA was confirmed by the high concentrations of ddI found both in the intestinal lumen and blood during 6-Cl-ddP perfusions and by a rate of ddI appearance in blood which was approximately 10-fold higher than ddI controls. Co-perfusion of the potent, hydrophilic ADA inhibitor DCF (Ki = 0. 001-0.05 nM) with 6-Cl-ddP led to only partial inhibition of intestinal ADA, while complete inhibition was obtained using the less potent but more lipophilic inhibitor EHNA (Ki = 1-20 nM). Hence, EHNA may be used to improve intestinal absorption of 6-Cl-ddP in vivo.     

Prostate specific origin of dipeptidylpeptidase IV (CD-26) in human seminal plasma

PURPOSE: A number of peptidases which can metabolize certain bioactive peptides and growth factors have been identified in seminal plasma. Our goal in this study was to determine molecular properties and the tissue source(s) for one of these peptidases, dipeptidylpeptidase IV (DPP IV), in human seminal plasma. MATERIALS AND METHODS: We measured the activities of DPP IV with the dipeptide glycylprolyl-p-nitroanalide and its molecular forms using immunoblotting of seminal plasmas of men who were vasectomized or with different sperm concentrations, and in prostatic and seminal vesicle secretions of men undergoing prostatic surgery. RESULTS: DPP IV in seminal plasma of vasectomized men was a membrane associated dimer comprised of subunits of approximately 110 kDa. Its activity did not differ in seminal plasmas of vasectomized, azoospermic, oligozoospermic and normozoospermic men indicating no correlation with the concentration of sperm originally present in the semen. The DPP IV antigen (CD -26) and enzymic activity were present in prostatic secretion, but absent from that of the seminal vesicles. These data indicate that the prostate gland is the primary source of DPP IV activity in seminal plasma. There was little variation in its activities in repeat seminal plasma samples from the same individual, and there was no change in its activity with age to 50 years. CONCLUSIONS: DPP IV in seminal plasma was derived from the prostate gland and it may be useful as a bioindicator of prostate function and/or disease with age in men.     

Nitric oxide-related vasoconstriction in lungs perfused with red cell lysate

The present study in isolated rat lungs demonstrates that nitric oxide gas (.NO, 70 nM) added to the perfusate containing a small amount of hemolysate [175 microliters of lysed red blood cells (RBC) per 50 ml of Earle's balanced salt solution (EBSS)] triggered profound and sustained vasoconstriction. Vasoconstriction was not observed when .NO was added to lungs perfused with washed intact rat or human RBC or with oxyhemoglobin (Hgb 20 microM). The presence of hemolysate in the perfusate also caused vasoconstriction in response to n-acetylcysteine (50 microM), glutathione (10(-4) M), or ascorbic acid (10(-4) M) and potentiated greatly the vasoconstrictor response to 5 mM KCl. Not only .NO, but also nitroprusside (SNP) or L-arginine and paradoxically three .NO synthesis inhibitors, including N-monomethyl L-arginine, L-NAME, and nitroblue tetrazolium, which have different mechanisms of action, each caused in the presence of hemolysate large vasoconstrictive responses. Hemolysate itself enhanced O2 consumption by slices of lung; no effects of this dose of .NO on lung slice respiration were seen in the absence of hemolysate. Both Hgb and hemolysate lowered perfusate cGMP levels to the same degree suggesting that the vasoconstrictive response was not due to unique effects of hemolysate on guanylyl cyclase. Addition of superoxide dismutase (SOD) and catalase (CAT) to the hemolysate containing perfusate, or addition of a cyclooxygenase or 5-lipoxygenase inhibitor, virtually abolished the .NO induced vasoconstriction. The latter data are consistent with the concept that exposure of the vasculature to hemolysate may result in the formation of peroxynitrite. However, SOD and CAT did not abolish the pulmonary vasoconstriction induced by L-arginine or by NAC. Our data indicate that hemolysate has profound effects on lung vessel tone regulation and on lung tissue mitochondrial function, yet the precise molecular mechanisms responsible for the action of hemolysate are likely to be very complex.     

The pharmacokinetics and metabolism of heptapeptide--a prospective synthetic analog of tuftsin with psychostimulating action in rats

The lymphocyte blast transformation test (LBTT) with three tuberculin dilutions was used to examine 190 patients with varying pulmonary tuberculosis activity, of them 63 patients received chemotherapy. According to the blast formation in the patients' cultured peripheral blood cells by three tuberculin dilutions, a correlation was found between the clinical manifestations of the process and the functional activity of T lymphocytes. Thus, the greatest percentage (500 TU) of blasts in LBTT per mean PPD dose was detectable in patients with low LBTT results by three tuberculin dilutions with positive dynamics during chemotherapy. With further positive dynamics, the proportion of blasts in the cultured peripheral blood cells was highest per high PPD doses (5000 TU). On the contrary, patients with progressive tuberculosis displayed a oppositely directed phasic pattern.     

Triangle-programmed coulometric nanotitrations completed by continuous flow with potentiometric detection

Coulometric nanotitrations were realized in a microchannel system using a continuous-flow titration technique with a triangle current-time profile. Redox and acid-base titrations were carried out on Fe(II) and nitric acid samples, respectively, with the same nanotitrator device. A linear relation between the concentration and the coulometric current transferred to the solution was found. The advantages of this universally applicable nanotitrator are fast response, low sample volume, high sensitivity, and high reproducibility as well as the convenience of handling an automated analyzer of the flow-through type.     

Characterization and growth regulation of a rat intrahepatic bile duct epithelial cell line under hormonally defined, serum-free conditions

Bile duct epithelial cells, or cholangiocytes, proliferate in vivo under a number of pathologic (i.e., partial hepatectomy) and pathophysiologic (i.e., bile duct ligation, malignant transformation) conditions. However, little is known about the possible growth factors that modulate these proliferative responses, in part because an in vitro model to study proliferation of nontransformed, normal cholangiocytes is not available. We report here the development of a rat cholangiocyte cell line (MMRC, minimal media-requiring rat cholangiocytes) that grows under hormonally defined, serum-free conditions on plastic and maintains a cholangiocyte phenotype. Morphologic as well as functional studies indicate that the cell line is polarized and actively transports fluid and electrolytes in an apical to basolateral direction. MMRC, when cultured for 24 mo. and passaged 80 times, have not undergone malignant transformation, because the cell line failed to grow under anchorage-independent conditions or in nude mice. Cellular proliferation is accelerated 2-8-fold by insulin, insulin-like growth factor 1, epidermal growth factor, and hepatocyte growth factor, growth factors known to stimulate tyrosine kinase receptors, and inhibited 2-10-fold by TGFbeta and IL-2. Glyco-conjugates of primary (i.e., cholic and chenodeoxycholic acid) and secondary bile acids (i.e., deoxycholic and lithocholic acid) do not alter proliferation at low concentration (1 microM), but are toxic at higher concentration (10 microM). In summary, we have developed and characterized a cholangiocyte cell line derived from normal rat liver, which grows under hormonally defined, serum-free conditions, maintains a nonmalignant, cholangiocyte phenotype, displays morphologic and functional features of polarity, and alters its proliferation rate in response to a variety of growth factors.     

Predicting performance during clinical years from the new Medical College Admission Test

The results of a predictive validity study of the new Medical College Admission Test (MCAT) using criteria from the clinical years of undergraduate medical education are presented and discussed. The criteria included course grades and faculty ratings of clerks in internal medicine, surgery, obstetrics and gynecology, pediatrics, and psychiatry; scores on a comprehensive test of clinical knowledge (including patient management type examinations); and scores on Part II of the examinations of the National Board of Medical Examiners (NBME). While the validity coefficients of the MCAT with the Part II examinations ranged from .03 to .47, they were higher than those of undergraduate grade-point averages with the same criteria. The implications of the small-to-medium size validity coefficients for admissions are discussed.