Bile acid metabolism is altered in multiple sclerosis and supplementation ameliorates neuroinflammation

Multiple sclerosis (MS) is an inflammatory demyelinating disorder of the CNS. Bile acids are cholesterol metabolites that can signal through receptors on cells throughout the body, including in the CNS and the immune system. Whether bile acid metabolism is abnormal in MS is unknown. Using global and targeted metabolomic profiling, we identified lower levels of circulating bile acid metabolites in multiple cohorts of adult and pediatric patients with MS compared with controls. In white matter lesions from MS brain tissue, we noted the presence of bile acid receptors on immune and glial cells. To mechanistically examine the implications of lower levels of bile acids in MS, we studied the in vitro effects of an endogenous bile acid, tauroursodeoxycholic acid (TUDCA), on astrocyte and microglial polarization. TUDCA prevented neurotoxic (A1) polarization of astrocytes and proinflammatory polarization of microglia in a dose-dependent manner. TUDCA supplementation in experimental autoimmune encephalomyelitis reduced the severity of disease through its effects on G protein-coupled bile acid receptor 1 (GPBAR1). We demonstrate that bile acid metabolism was altered in MS and that bile acid supplementation prevented polarization of astrocytes and microglia to neurotoxic phenotypes and ameliorated neuropathology in an animal model of MS. These findings identify dysregulated bile acid metabolism as a potential therapeutic target in MS.

One-year clinical performance of a resin-modified glass ionomer and a resin composite restorative material in unprepared Class V restorations

This study evaluated the clinical performance and appearance of a resin-modified glass ionomer and a resin composite over one year. Thirty-seven pairs of restorations of Fuji II LC and Z250/Single Bond were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline and 6 and 12 months, using modified Ryge/USPHS criteria. No significant difference (p>0.05) was observed in performance of both materials, although retention of the Z250 restorations was below the minimum specified in the ADA Acceptance Program for Dentin and Enamel Adhesives. Little difference in the restorations' appearance was observed.

Linked linear amplification: a new method for the amplification of DNA

BACKGROUND

Linked Linear Amplification (LLA) is a new nucleic acid amplification method that uses multiple cycles of primer extension reactions. The presence of nonreplicable elements in LLA primers renders primer extension products unusable as templates for further amplification, leading to linear accumulation of products. Through the use of nested primers, linear reactions can be "linked", providing total amplification yields comparable to those obtained by PCR.

METHODS

The LLA model predicts (a) that amplification yield will approach that of PCR as the number of primers increases and (b) that the unique composition of LLA products will give lower carryover amplification efficiency compared with PCR. To test these hypotheses, the human ss-globin gene was amplified by 10-, 14-, or 18-primer LLA and the yield was compared with PCR. Carryover contamination was simulated by reamplifying a dilution series of LLA or PCR products. To demonstrate the clinical utility of the method, LLA coupled with allele-specific oligonucleotide (ASO) capture was used to detect the factor V Leiden mutation in a panel of 111 DNA samples.

RESULTS

Fourteen- and 18-primer LLA gave amplification yields comparable to PCR. However, LLA carryover amplification efficiency was four orders of magnitude lower than that of PCR. The LLA-ASO assay detected the correct factor V Leiden genotype in all 111 samples.

CONCLUSIONS

LLA is a robust target amplification method that is comparable to PCR in yield. However, LLA is more resistant to false results caused by carryover amplicon contamination.

Contracting with outpatient hemodialysis patients to improve adherence to treatment

The purpose of this study was to examine the relationship between contingency contracting and adherence to prescribed therapy in outpatient chronic hemodialysis patients. A quasi-experimental, pretest/posttest design was used. The sample included 15 hemodialysis patients, 6 in the phosphorus group and 9 in the weight-gain group. The study was conducted at an outpatient hemodialysis center in a Midwestern rural state. Specific variables investigated were interdialytic weight gains and serum phosphorus levels that reflect adherence to fluid restrictions and to taking phosphate-binding medications. Weekly interviews were conducted with each patient and content analysis of interview data was completed to identify categories related to adherence and nonadherence. Pre- and postcontract weight gains and phosphorus levels were analyzed with a paired two sample t-test. The categories related to adherence and nonadherence included physiological, psychological, environmental, locus of control/self-control/self-praise, economical, medical, knowledge deficit, health benefits, family support, and social support. Adherence to taking phosphate-binding medication responded more favorably to contingency contracting than did adherence to fluid restrictions. Chronic outpatient hemodialysis patients in the sample responded to the use of contingency contracting and developed techniques to remember to take phosphate-binding medications in order to lower serum phosphorus medications.

Evaluation of the BeTha gene 1 kit for the qualitative detection of the eight most common Mediterranean beta-thalassemia mutations

We describe the evaluation of the Bio-Rad BeTha Gene 1 kit (Bio-Rad Laboratories, Hercules, CA), a DNA-probe assay designed for the qualitative determination of the eight most common Mediterranean beta-thalassemia mutations. The kit utilizes the principle of allele-specific oligonucleotide (ASO) hybridization. Following sample preparation and in vitro DNA amplification by the polymerase chain reaction (PCR), an allele-specific detection of the amplified products by a nonradioactive enzymatic assay is performed. Genomic DNA is prepared from an individual's whole blood with a DNA purification matrix. In a second step, the beta-globin gene is amplified in a multiplex PCR reaction containing four 5' biotinylated oligonucleotide primers. In a final step, an aliquot of the PCR reaction is first chemically denatured and then captured in two eight-well strips of a 96-well enzyme-linked immunosorbent assay (ELISA) plate by hybridization to an immobilized ASO probe. Each DNA sequence at each of the eight mutation sites is represented by one normal and one mutant ASO. During this capture/hybridization step, which is performed at 37 degrees C, only perfectly matched PCR products will be captured by an ASO. Subsequently, the allele-specific captured biotin-labeled PCR products are detected by a colorimetric enzymatic reaction. The system permits the detection of 16 beta-thalassemia alleles using a high-throughput format that can be automated easily. A clinical feasibility study was performed to evaluate the functionality (method comparison study, assay validity using samples previously collected and stored at various temperatures for different periods of time, interference on kit performance, and assay validity for prenatal diagnosis) and the usability (ease of use, sample throughput) of the kit. The analysis of 110 samples previously studied with reference methods showed 100% clinical sensitivity and specificity. We demonstrate here that the procedure not only increases the throughput of beta-thalassemia allele genotyping but also provides an accurate, rapid, reliable, and nonisotopic diagnostic tool.

Enteropathogenic bacteria in the La Paz River of Bolivia

Diarrheal diseases often result from ingestion of contaminated water or food. The population of La Paz, Bolivia is directly or indirectly exposed to the sewage-contaminated La Paz River. We conducted a bacteriologic survey of the La Paz River to quantify the level of bacterial contamination, with particular reference to enteropathogens. A total bacterial count exceeding 10(6) colony-forming units (CFU)/ml, including lactose fermenting and nonfermenting, gram-negative bacilli of approximately 10(5) CFU/ml, respectively, were detected in river water samples collected near two densely populated areas. A total bacterial count of 10(5) CFU/ml was also detected at the most downstream area of the river near a sparsely populated area. At four sampling locations, several enteropathogens were detected, including five enterotoxigenic Escherichia coli (ETEC) (serotype O6, O15, and O159), two enteropathogenic E. coli (EPEC) (serotype O44), two enteroinvasive E. coli (EIEC) (serotype O29), and three Salmonella O4 group isolates. The heat-labile enterotoxin gene and the invasive toxin gene were detected in all ETEC and EIEC isolates by polymerase chain reaction analysis. Nine isolates of E. coli were found by the agar dilution method to be susceptible to ampicillin, kanamycin, nalidixic acid, tetracycline, and chloramphenicol, and ampicillin resistance was found in only two isolates of EIEC 7-4 (serotype O29) and EPEC 7-5 (serotype O44). Ampicillin resistance was coded on plasmids and transferred conjugatively to E. coli chi1037 at a frequency of 10(-5) CFU/donor by the broth mating method. Strains of Aeromonas caviae, which can cause diarrheal disease in infants, were detected in vegetables grown in fields irrigated by water from the La Paz River. The survival of nine isolates of E. coli in filtered river water was compared with that of laboratory strains (E. coli chi1037, W3110, and ATCC29577). The survival time of seven isolates, excluding two ampicillin-resistant isolates, was markedly longer than that of the laboratory strains. Our results show a high bacterial contamination of the La Paz river and suggest that such levels may contribute to the high incidence of diarrheal disease in the city of La Paz.

Ligase chain reaction assay for human mutations: the Sickle Cell by LCR assay

We can detect the beta-globin gene sickle cell mutation by using an assay based on the ligase chain reaction. The simultaneous amplification of the human growth hormone gene in the same reaction serves as a control for the amount of template DNA or amplification efficiency. Ligation products, which are biotinylated at one end and tagged with an arbitrary "tail" sequence at the other, are captured by hybridization to "tail"-complementary oligonucleotides immobilized on polystyrene microwells. The captured ligation products are detected colorimetrically by use of streptavidin-alkaline phosphatase conjugate. In a study of 24 subjects, the assay unequivocally discriminated among normal, carrier, and sickle cell genotypes.

Major enteropathogenic bacteria isolated from diarrheal patients in Bolivia: A hospital-based study

A total of 1,234 fecal samples from diarrhea cases were examined for etiological bacterial agents at medical facilities in La Paz and Sucre, Bolivia. Eighty strains of Shigella spp., 39 strains of Salmonella spp., 29 strains of Vibrio cholerae, and 222 strains of enteropathogenic Escherichia coli (139 EPEC, 55 ETEC, 29 EIEC, and 1 EHEC) were isolated. With regard to the serovars of Shigella, S. flexneri 2a, 3a, and 1b were predominant. In the case of Salmonella, S. enteritidis was the most common, followed by S. typhi, S. poona, and S. paratyphi B. Out of 29 cholera strains, 25 belonged to biovar El Tor, serovar Ogawa while the remaining 4 were serovar Inaba. Among 55 strains of ETEC serotypes, 5 showed ST producers but none showed LT producers. Likewise, among 55 strains of enterohemorrhagic serotypes, only one strain (O157:H7) produced verocytotoxin (VT 2). The results of drug sensitivity tests revealed the predominance of Shigella, EPEC, and ETEC strains resistant to aminobenzil-penicillin (ABPC) and trimethoprim. Since diarrheal patients in Bolivia are treated mainly with ABPC or sulfamethoxazole/trimethoprim (SXT) and rarely with gentamicin, kanamycin, or other drugs, it is possible that ABPC- and SXT-resistant strains will increase and persist in the near future.

Stable high expression of human gamma-aminobutyric acidA receptors composed of alpha and beta subunits

Multiple classes of pharmacological agents including benzodiazepines, cage convulsants like t-butylbicyclophosphorothionate (TBPS), barbiturates and neuroactive steroids allosterically modulate the gamma-aminobutyric acidA receptor-chloride ionophore complex (GRC). The function of benzodiazepines requires a GRC comprised of alpha, beta and gamma subunits, while TBPS, barbiturates and neuroactive steroids will allosterically modulate GRCs comprised of only alpha and beta subunits. Binary alpha beta complexes are still hypothesized to be expressed in the mammalian brain particularly during development and could contribute to the pharmacological action of neuroactive steroids and barbiturates. In order to examine binary alpha beta complexes we report here the establishment of stable cell lines that express high levels of human GABAA receptors comprised of alpha 1 beta 1, alpha 2 beta 1 and alpha 3 beta 1 subunit combinations. The apparent potencies for allosteric modulation of [35S]TBPS for most naturally occurring neuroactive steroids for the binary subunit combinations was similar to that of the gamma-containing subunit combinations. Also discussed is the usefulness of these cell lines for the biophysical analysis of the GABAA receptor stoichiometry.

Recombinant human erythropoietin stimulates angiogenesis in vitro

Endothelial cell migration and proliferation are the key steps in the angiogenic process, and both are stimulated by recombinant human erythropoietin (rHuEPO). In addition rHuEPO can increase endothelin-1 (ET-1) release by the endothelial cell. We designed the present study to address the question of whether rHuEPO stimulates angiogenesis. An in vitro quantitative assay for angiogenesis was used. This consisted of rat aortic rings embedded in a reconstituted basement membrane matrix and incubated with and without rHuEPO for eight days. We found that rHuEPO increased vessel outgrowth after four days of culture and this was continued for the next four days (rHuEPO vs. control: day 4, 12 +/- 2 vs. 4 +/- 1, P < 0.002 and day 8, 124 +/- 18 vs. 56 +/- 12 P < 0.006). Supernatant endothelin-1 (ET-1) levels, at 24 hours, were significantly higher than controls in the rings incubated with rHuEPO (107 +/- 13 vs. 43 +/- 10 pg/ml, P < 0.003). To investigate the role of ET-1 in rHuEPO-induced angiogenesis, rings were exposed to ET-1 alone (10(-8) M). We observed an increase in microvessel formation compared to control (day 4, 4 +/- 2 vs. 2 +/- 1, P < 0.006, and day 8, 67 +/- 12 vs. 51 +/- 10, P < 0.03). In addition, aortic rings were co-cultured with rHuEPO and anti-ET-1 IgG antibody. Stimulation of angiogenesis by rHuEPO was blunted by the ET-1 antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of arginine in health and in renal disease

In addition to participating in protein synthesis in cells and tissues, L-arginine is essential for the synthesis of urea, creatine, creatinine, nitric oxide, and agmatine and influences hormonal release and the synthesis of pyrimidine bases. This places L-arginine, its precursors and its metabolites at the center of the interaction of different metabolic pathways and interorgan communication. Thus L-arginine participates in changing the internal environment in different but simultaneous ways, ranging from disposal of protein metabolic waste, muscle metabolism, vascular regulation, immune system function, and neurotransmission, to RNA synthesis and hormone-mediated regulation of the internal milieu. In normal rats, inhibition of the nitric oxide pathway results in systemic hypertension and decreased glomerular filtration rate and effective renal plasma flow. If the inhibition of this pathway is sustained, then glomerulosclerosis and death from uremia follow. Dietary intervention with L-arginine has resulted in amelioration of a number of experimental kidney diseases, such as those caused by subtotal nephrectomy, diabetic, nephropathy, cyclosporin A administration, salt-sensitive hypertension, ureteral obstruction, puromycin amino-nucleoside nephrosis, kidney hypertrophy due to high-protein feeding, and glomerular thrombosis due to administration of lipopolysaccharide. The present review addresses the current evidence for the beneficial effects of dietary intervention with L-arginine in a number of experimental renal diseases and describes the basis for the concept of L-arginine deficiency (absolute or relative) in certain settings in which supplementation of the diet with this amino acid may be beneficial.

Identification of the GABAA receptor subtype mRNA in human pancreatic tissue

Evidence suggests a physiological role of the GABAA receptor in the pancreas. Clinically, an autoimmune reaction involving the GABA biosynthesizing enzyme, glutamic acid decarboxylase has been implicated in the development of insulin-dependent diabetes mellitus. To determine the subtypes of GABAA receptor expressed in human pancreas, we analyzed, with the use of the reverse-transcription/polymerase chain reaction technique human pancreatic tissue for the presence of GABAA receptor subunits alpha 1-6, beta 1-3, and gamma 1-2 transcripts. Unlike brain tissue, pancreatic tissue only expresses the alpha 2, beta 3 and gamma 1 subunits. Our results provide evidence of a specific GABAA receptor subtype expressed in human pancreatic tissue.

Dietary supplementation of L-arginine ameliorates renal hypertrophy in rats fed a high-protein diet

Ingestion of a high-protein diet or intravenous administration of amino acids is associated with an increase in glomerular filtration rate (GFR). It can also lead to renal hypertrophy, and, if sustained, may cause glomerular sclerosis. L-Arginine administration ameliorates the progression of renal disease in rats with subtotal nephrectomy and prevents the increase in GFR observed in rats with experimental diabetes. The present study examines the potential effect(s) of L-arginine administration (1%) in the drinking water on the renal hypertrophy that occurs in rats fed a high-protein diet for 1 month. Four groups of female Sprague-Dawley rats, six in each group, were studied (95 +/- 1 g). Groups 1 and 2 were fed a low-protein diet (12% casein, 0.504% L-arginine); Group 1 was given tap water, whereas Group 2 was given tap water supplemented with L-arginine. Groups 3 and 4 were fed a high-protein diet (40% casein, 1.68% L-arginine); Group 3 was given tap water, whereas Group 4 was given tap water supplemented with L-arginine. The rats had free access to food and water during the study period. The kidney weight and the kidney to body weight ratio of rats of Group 3 were significantly greater than in the other groups of rats. Renal hypertrophy was prevented in the rats of Group 4. The excretion of orotic acid in the urine, an index of L-arginine deficiency, was significantly greater in rats of Group 3 than in rats of Group 4. Thus, the renal hypertrophy that occurs in rats fed a high-protein diet was decreased in rats given L-arginine supplementation in the drinking water. This effect was associated with less excretion of orotic acid in the urine in rats given L-arginine. A relative deficiency of L-arginine may occur during high-protein feeding that may shunt nitrogen metabolism from the urea cycle to the orotic acid pathway.

L-arginine decreases the infiltration of the kidney by macrophages in obstructive nephropathy and puromycin-induced nephrosis

We examined the effect of 1% L-arginine in the drinking water on the infiltration of the kidney by macrophages in rats with puromycin aminonucleoside-induced nephrosis (PAN) and in rats with bilateral ureteral obstruction (BUO) of 24 hours duration. Rats given L-arginine in the drinking water for three days before BUO or PAN was initiated had a greater glomerular filtration rate after release of BUO or induction of PAN than similar rats not given L-arginine (P < 0.0001). Administration of L-arginine decreased the renal infiltration by macrophages in rats with PAN (P < 0.0001) or BUO (P < 0.0001) compared to rats with PAN or BUO given tap water alone. Chemotaxis studies suggested that macrophages were activated during obstruction as evidenced by the greater random migration of peritoneal macrophages obtained from rats with 24-hour urethral obstruction than from sham-operated rats (SOR; P < 0.0001). In vitro, maximal chemotaxis induced by 7% zymosan-activated serum (ZAS) in peritoneal macrophages from SOR was enhanced by low (10(-6) to 10(-5) M) and decreased by high concentrations (10(-3) to 10(-2) M) of L-arginine in the incubation medium. Migration of macrophages from rats with urethral obstruction was increased by 7% ZAS but the increase diminished with high concentrations of L-arginine (10(-3) to 10(-2) M). Random migration of peritoneal macrophages obtained from rats with urethral obstruction given L-arginine prior to obstruction was significantly lower than that of peritoneal macrophages obtained from similar rats given tap water alone prior to obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Low plasma and renal tissue levels of L-arginine in rats with obstructive nephropathy

Rats with bilateral ureteral obstruction (BUO) of 24 hours duration had significantly lower plasma levels of L-arginine than at baseline (P < 0.0001), but no significant changes occurred in sham-operated rats (SOR). In contrast, rats with bilateral nephrectomy had greater plasma levels of L-arginine four hours (P < 0.03) and 24 hours (not significant) after nephrectomy than at baseline. Total body irradiation prior to obstruction prevented the decrease in plasma levels of L-arginine in rats with BUO but had no effect on these values in SOR. Renal tissue levels of L-arginine were 20% lower in rats with BUO than in SOR. Total body irradiation prior to BUO resulted in greater renal tissue levels of L-arginine than occurred in nonirradiated rats with BUO (P < 0.002). Total body irradiation did not effect renal tissue levels of L-arginine in SOR. Excretion of reactive nitrogen intermediates in urine (URNI), indicative of L-arginine metabolism through the nitric oxide pathway, was lower in rats with BUO than in SOR (P < 0.001). Proximal tubules from rats with BUO synthesized less L-arginine than those from SOR (P < 0.02). The results indicate that: (1) decreased levels of L-arginine in plasma and renal tissue of rats with BUO correlate with leukocyte infiltration of the kidney, and (2) decreased synthesis of L-arginine occurs in proximal tubules of rats with BUO when compared to tubules from SOR.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary supplementation with L-arginine ameliorates glomerular hypertension in rats with subtotal nephrectomy

This study was designed to examine the potential effect(s) of dietary supplementation with L-arginine on the renal microcirculation of female Munich-Wistar rats with ablation of 60 to 70% of total renal mass. All rats were fed a standard rat chow containing 22.8% protein (1.42% L-arginine). Groups 1 (N = 6) and 3 (N = 7) drank tap water and had micropuncture studies after 5 to 6 or 15 to 16 wk, respectively, of subtotal renal ablation. Groups 2 (N = 5) and 4 (N = 7) drank tap water supplemented with L-arginine (1%) and had micropuncture studies after 5 to 6 or 15 to 16 wk, respectively, of subtotal renal ablation. Glomerular micropuncture studies revealed no differences in any of the parameters of glomerular hemodynamics measured 5 to 6 wk after renal ablation (Groups 1 versus 2). However, by 15 to 16 wk postnephrectomy, values of glomerular capillary pressure and efferent arteriolar resistance were significantly greater and the glomerular capillary ultrafiltration coefficient was significantly lower in rats drinking tap water than in rats drinking tap water supplemented with L-arginine. Single-nephron GFR, single-nephron plasma flow rate, and afferent arteriolar resistance were not different between these two groups. The data suggest that the long-term administration of L-arginine prevents the progression of glomerular sclerosis in rats with subtotal nephrectomy, at least in part, by ameliorating glomerular capillary hypertension.

L-arginine administration prevents glomerular hyperfiltration and decreases proteinuria in diabetic rats

The effect(s) of L-arginine administration on the renal function of rats with untreated diabetes mellitus was examined. Rats received streptozotocin (N = 11) or vehicle (N = 12): Group 1 (normal rats, N = 6) drank tap water; Group 2 (normal rats, N = 6) drank tap water containing 1% L-arginine; Group 3 (diabetic rats, N = 5) drank tap water; and Group 4 (diabetic rats, N = 6) drank tap water with 1% L-arginine. Rats were fed a standard rat chow diet (22.8% protein, 142% L-arginine) with free access to food and water for 14 wk. Diabetic rats gained less weight, had significantly lower plasma levels of albumin and L-arginine, and had greater values for 24-h urine volumes and urine excretion of glucose, protein, urea, creatinine, nitrate, and nitrite than control rats. Diabetic rats given L-arginine (Group 4) had significantly lower protein and cGMP excretion in the urine than did rats of Group 3. The administration of L-arginine did not affect the plasma levels of glucose or L-arginine in Groups 2 or 4 compared with those of their respective controls. Group 3 had significantly higher values for GFR than did the other three groups of rats, but values for effective RPF, mean arterial pressure, hematocrit, and renal vascular resistance were not significantly different between Groups 3 and 4. There was no significant difference in glomerular morphology among the four groups of rats as determined by light microscopy, and both groups of diabetic rats exhibited the Armanni-Ebstein lesion in their tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Distinct NCAM splicing events are differentially regulated during rat brain development

Primary transcripts for the neural cell adhesion molecule NCAM are highly alternatively spliced potentially giving rise to over 100 different mRNA forms. These mRNAs encode three major polypeptide isoforms of 120, 140, and 180 kDa each of which is thought to be composed of a mixture of polypeptides that differ by the variable presence of small exons at two locations. These NCAM 'microsplicing' patterns were examined within mRNA populations encoding each of the major isoforms to identify exactly which NCAM forms are present during brain development. The proportion of NCAM mRNAs containing at the exon 7/8 junction the alternatively microspliced 30 bp VASE exon increased similarly during brain development in mRNAs encoding all three major size classes. Perinatal brain, cultures of neurons from embryonic rats, and of glia from newborn rats all had low VASE levels while about 50% of the mRNAs in adult brain expressed VASE. In contrast, microsplicing at the exon 12/exon 13 junction was differentially regulated among NCAM major size classes. mRNAs containing microspliced exons totaling 3.15, or 18 base pairs (bp) represented greater than 50% of the total mRNAs encoding the 120 kDa forms at all ages. However, these exons were present in less than 15% of the 140 and 180 kDa encoding mRNAs in rats older than embryonic day 15. Similar results at the exon 12/13 junction were observed with mRNAs from neuronal cultures while glial cultures had greater levels of a 3 bp pair exon at this junction.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytochrome P-450 pathway in renal function of normal rats and rats with bilateral ureteral obstruction

Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) are decreased and mean arterial pressure (MAP) and renal vascular resistance (RVR) are increased after unilateral release of bilateral ureteral obstruction (BUO) of 24 hr duration. An imbalance between vasoconstrictor and vasodilator substances may explain these hemodynamic changes. We examined the role of the cytochrome P-450 pathway in this setting. After unilateral release of BUO, GFR and ERPF (ml/min/kg body wt) were significantly lower in these rats than in sham-operated rats (SOR) 1.14 +/- 0.09 vs 6.7 +/- 0.5 and 3.09 +/- 0.2 vs 23.5 +/- 3.4, respectively). BUO rats had significantly higher MAP (mm Hg) and RVR (mm Hg/ml/min/kg body wt) than SOR (155 +/- 5 vs 120 +/- 1 and 29.1 +/- 1.7 vs 3.2 +/- 0.4, respectively). SOR given 3-methylcholanthrene and beta-naphthoflavone to induce the cytochrome P-450 system had no significant changes in renal function, RVR, or MAP. SOR given ketoconazole to inhibit the cytochrome P-450 system had significantly lower GFR (4.8 +/- 0.5) than temporal control rats without significant changes in ERPF (21.2 +/- 4.6), MAP (127 +/- 6), or RVR (4.2 +/- 0.9). Rats with BUO given ketoconazole had lower but not significantly different GFR (0.84 +/- .1) and ERPF (2.61 +/- .4) than BUO controls. Values for MAP did not differ in BUO rats given ketoconazole versus BUO temporal controls. BUO rats given 3-methylcholanthrene and beta-naphthoflavone had significantly higher GFR and ERPF (2.01 +/- 0.24 and 6.66 +/- 1.36, respectively) and significantly lower RVR (14.7 +/- 3.9) than control rats with BUO; MAP was unchanged. Microsomal preparations from indomethacin-treated isolated kidneys obtained from BUO rats when compared with preparations obtained from SOR had significantly less activity of the P-450 cytochrome-dependent omega/omega-1 hydroxylase (103 +/- 6 vs 130 +/- 7 pmol hydroxyeicosatetraenoic acids produced per mg of protein/min, P < 0.02) and the P-450 cytochrome-dependent epoxygenase (11 +/- 0.3 vs 30 +/- 4 pmol lipoxyeicosatrienoic acids produced per mg of protein/min, P < 0.04). Indomethacin-treated microsomes prepared from kidneys of BUO rats converted significantly less 14C-arachidonic acid through the P-450-dependent hydroxylases (13.5 +/- 0.8 vs 17.0 +/- 0.1% of 14C-arachidonic acid converted to 19- and 20-hydroxyeicosatetraenoic acids, P < 0.02), and significantly less through the epoxygenases (1.4 +/- 0.4 vs. 3.8 +/- 0.5% of 14C-arachidonic acid converted to epoxyeicosatrienoic acids).(ABSTRACT TRUNCATED AT 400 WORDS)

Renal function after release of ureteral obstruction: role of endothelin and the renal artery endothelium

Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) are decreased and mean arterial pressure (MAP) is increased after unilateral release of bilateral ureteral obstruction (BUO). An imbalance between vasoconstrictor and vasodilator substances may explain the hemodynamic alterations seen in this setting. The present study examines the role of endothelin-1 in such alterations. Rats with BUO (N = 10) had significantly lower GFR and ERPF (ml/min/kg body wt) than sham-operated rats (SOR, N = 9) (1.40 +/- 0.14 vs. 6.20 +/- 0.38 and 5.12 +/- 0.68 vs. 20.2 +/- 2.20, respectively) and significantly higher MAP (mm Hg) than SOR (154.9 +/- 3.2 vs. 120.6 +/- 1.7). Rats with BUO given a specific antiendothelin antibody (N = 8) had significantly higher GFR (2.10 +/- 0.12) and ERPF (7.46 +/- 0.95) than BUO control rats, but there were no significant changes in MAP (159.5 +/- 5.8). In SOR (N = 6), mechanical denudation of the main renal artery endothelium did not significantly affect renal function when compared to renal function in control SOR. However, the same maneuver significantly lowered GFR (0.64 +/- 0.17) and ERPF (1.67 +/- 0.36) in BUO rats (N = 5) when compared to BUO control rats. We conclude that: (1) endothelin-1 has a significant vasoconstrictor role in rats with BUO of 24 hours duration and accounts for a portion of the decrease in glomerular filtration rate seen in rats after unilateral release of bilateral ureteral obstruction, and (2) in the BUO setting, the net role of the renal artery endothelium is vasodilatory.

Dietary supplementation with L-arginine ameliorates the progression of renal disease in rats with subtotal nephrectomy

We studied the effect of dietary supplementation with L-arginine for 6 weeks on the progression of renal disease in female Sprague-Dawley rats subjected to sham-operation (groups 1 and 2) or surgical ablation of 85% to 90% of the total renal mass (groups 3 and 4). All rats were fed a standard rat chow containing 22.8% protein. Rats in groups 1 (n = 5) and 3 (n = 9) served as controls and drank tap water ad libitum. Rats in groups 2 (n = 6) and 4 (n = 6) drank tap water supplemented with 1% L-arginine. Rats in groups 1 and 2 had similar values for glomerular and tubular function and serum chemistries 6 weeks after sham-operation. Sham-operated rats given L-arginine had significantly greater urine urea excretion than similar rats drinking tap water. Rats with subtotal nephrectomy (groups 3 and 4) had a significantly higher blood pressure, greater proteinuria, and a significantly lower plasma albumin than sham-operated rats (groups 1 and 2). Rats with remnant kidneys given 1% L-arginine (group 4) had significantly greater values for glomerular filtration rate (GFR) and P-amino hippurate (PAH) clearance than similar rats given tap water (group 3), despite comparable levels of systemic blood pressure, hematocrit, body weight, plasma chemistries, including L-arginine, and urine chemistries, except urea excretion. The remnant kidney of rats given L-arginine (group 4) had a greater number of normal or minimally abnormal glomeruli and fewer interstitial changes than that of rats given tap water (group 3).(ABSTRACT TRUNCATED AT 250 WORDS)

EDRF role in renal function and blood pressure of normal rats and rats with obstructive uropathy

There is a decrease in glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) and an increase in mean arterial pressure (MAP) and renal vascular resistance (RVR) after release of bilateral ureteral obstruction (BUO) of 24 hours duration. The present studies examine the role of endothelium-derived relaxing factor (EDRF) in the renal hemodynamics of sham-operated rats (SOR) and rats in which BUO of 24 hours duration was unilaterally released. In both groups of rats, renal function and blood pressure were measured in the awake state under basal conditions and after administration of L-arginine (L-arg), the substrate for EDRF synthesis, followed by NwNAME, an L-arg antagonist, or after administration of NwNAME followed by L-arg. Administration of L-arg alone to SOR did not affect renal function, MAP or RVR. In SOR given L-arg and then NwNAME, there was significantly decreased GFR and ERPF and increased MAP and RVR. When NwNAME was given initially, similar changes were obtained, and these were reversed by the administration of L-arg. Rats given L-arginine immediately after unilateral release of BUO of 24 hours duration had significantly greater GFR and ERPF values and lower MAP and RVR than temporal controls. NwNAME given to BUO rats decreased renal function further and increased MAP and RVR. We found a dose-dependent increase in GFR and ERPF and a dose-dependent decrease in MAP and RVR in both SOR and rats with BUO given increasing amounts of L-arg. There was also a dose-dependent decrease in GFR and ERPF and an increase in MAP and RVR in SOR and rats with BUO given increasing amounts of NwNAME or NGNMA, the two different antagonists of L-arg. In another set of experiments, SOR and rats with BUO were given L-arg preoperatively (that is, 24 hr prior to study). Both groups of rats had significantly higher GFR and ERPF values and lower MAP and RVR than control rats. Sham-operated rats given NwNAME 24 hours prior to study had significantly lower GFR and ERPF and higher MAP and RVR than untreated rats. Rats with BUO given NwNAME prior to obstruction had no measurable renal function and had significantly higher values for MAP after release of obstruction. These studies confirm the role of L-arg administration, and presumably EDRF, in the regulation of MAP and renal function in sham-operated rats. The results of this study also suggest decreased availability of arginine for EDRF synthesis in rats with BUO.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of the 5-lipooxygenase pathway in obstructive nephropathy

Leukotrienes are products of the 5-lipooxygenase pathway of arachidonic acid metabolism that possess potent inflammatory properties. We examined the potential role of this pathway in the decrease in glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) observed in rats after unilateral release of bilateral ureteral obstruction (BUO) of 24 hours duration. Isolated glomeruli from rats with BUO produced significantly greater amounts of leukotriene B4 (LTB4) than glomeruli from sham-operated rats (SOR; P less than 0.0001). Glomeruli from rats with BUO given MK886, an inhibitor of the 5-lipooxygenase enzyme, or from rats with BUO subjected to both total body irradiation to prevent the leukocyte infiltration of the kidney and also given MK886 prior to obstruction, produced amounts of LTB4 not significantly different from those in glomeruli of SOR. Glomeruli from rats with BUO that had only total body irradiation prior to obstruction produced significantly less LTB4 than glomeruli from untreated BUO rats, but LTB4 production was still significantly greater than in glomeruli from SOR. There were no significant differences in GFR among SOR, SOR given MK886, and SOR subjected to total body irradiation. However, SOR given MK886 had significantly higher ERPF and lower renal vascular resistance (RVR) than SOR not pretreated with the lipooxygenase inhibitor. Rats with BUO given MK886, or subjected to total body irradiation, or both, prior to obstruction had significantly greater GFR and ERPF values and lower RVR than untreated BUO rats. Glomeruli from rats with BUO which were not pretreated had three times the leukocytes of glomeruli from SOR. This leukocyte infiltrate was composed of macrophages (about 55%) and neutrophils (about 45%).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of platelet-activating factor in renal function in normal rats and rats with bilateral ureteral obstruction

Platelet-activating factor (PAF) is a powerful vasodilator with important effects on kidney function. It has been suggested that the renal effects of PAF are mediated by thromboxane A2 (TxA2). We examined the effect of PAF on renal function in sham-operated rats and rats that had undergone unilateral release of bilateral ureteral obstruction (BUO) of 24-hr duration, a condition in which the synthesis of TxA2 is increased. To eliminate systemic hemodynamic changes, PAF was infused directly into the left renal artery using the lowest dose that affected renal function (2.3 x 10(-13) moles/min). Infusion of PAF significantly decreased the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in normal rats and rats with BUO. Normal (sham-operated) rats pretreated with an inhibitor of TxA2 synthesis also had a significant decrease in GFR after administration of PAF (ERPF also decreased, but not significantly). Rats with BUO pretreated with an inhibitor of TxA2 synthesis had significantly greater basal GFR and ERPF (increases of 72 and 171%, respectively) than untreated BUO rats. Administration of PAF to the former group further increased GFR and ERPF (by 37 and 39%, respectively; P less than 0.001). The role of endogenous PAF was evaluated by administering a specific PAF receptor antagonist. Sham-operated rats pretreated with high doses of the PAF receptor antagonist had significantly higher mean arterial pressure values than normal untreated rats, and had no decrease in GFR and ERPF during PAF infusion. Rats with BUO pretreated with the PAF antagonist had a significant, dose-dependent decrease in basal GFR and ERPF. These data suggest that endogenous PAF has a vasodilatory role in obstructive nephropathy. No significant differences in eicosanoid excretion in the urine corrected per GFR were observed during infusion of PAF in any of the groups examined. In BUO rats with intact TxA2 synthesis, exogenous administration of PAF decreased renal function, presumably through further increases in the production of TxA2. However, when TxA2 production was inhibited, PAF administration increased GFR and ERPF, presumably due to its unopposed vasodilatory properties. The data suggest an important role of PAF in the hemodynamic changes seen in obstructive nephropathy.

Role of vasopressin in rats with bilateral ureteral obstruction

After unilateral release of bilateral ureteral obstruction (BUO), there is a significant increase in renal vasoconstriction that accounts for the marked decrease in glomerular filtration rate and effective renal plasma flow seen in this setting. We examined the potential role of antidiuretic hormone (ADH), a vasoconstrictor of the renal circulation, on renal hemodynamics in female Sprague-Dawley rats with BUO of 24-hr duration. Rats with BUO had significantly higher plasma values of ADH 65.1 +/- 12.2 vs. 12.1 +/- 4.1 pg/ml), sodium (145.4 +/- 0.91 vs 138.6 +/- 1.06 mEq/liter), and osmolality (375.6 +/- 2.0 vs 310.1 +/- 3.6 mOsm/kg) than sham-operated rats. Rats with BUO pretreated with enalapril, an angiotensin-converting enzyme inhibitor, before obstruction had somewhat higher, but not significantly different, plasma values for ADH (84.6 +/- 20.8 pg/ml) than rats with BUO not given enalapril. Rats with unilateral ureteral obstruction of 24-hr duration had plasma levels of ADH (8.2 +/- 1.3) not different from those in sham-operated rats. Rats with BUO pretreated with a specific antagonist of the V1-type receptor for ADH had significantly greater values for the glomerular filtration rate (2.31 +/- 0.24 vs 1.44 +/- 0.08 ml/min/kg body wt) and the effective renal plasma flow (8.95 +/- 0.71 vs 3.81 +/- 0.44 ml/min/kg body wt) and significantly lower values for mean arterial pressure (140.3 +/- 2.0 vs 159.1 +/- 5.5 mm Hg) than did BUO rats not given the antagonist. The results indicate that high levels of ADH play an important role in the decrease in the glomerular filtration rate and effective renal plasma flow observed in rats with BUO of 24 hr. The significant increase in ADH levels after BUO of 24-hr duration may be due to an increase in osmotic stimulation as a consequence of hypernatremia. Activation of the renin-angiotensin axis, known to occur after BUO or unilateral ureteral obstruction of 24-hr duration, does not appear to have a role in the increased circulating levels of ADH.

Structure of the human gastric H,K-ATPase gene and comparison of the 5'-flanking sequences of the human and rat genes

We have isolated and analyzed the genes encoding the human and rat gastric H,K-ATPase catalytic subunits. The complete sequence of the human gene, including 2.2 kb of 5'-flanking sequence, and the 5' end of the rat gene, including exons 1-4 and 2.5 kb of 5'-flanking sequence, have been determined. The human gene contains 22 exons. Its intron-exon organization is identical to that of the Na,K-ATPase gene, except that exon 6 corresponds to a fusion of exons 6 and 7 of the Na,K-ATPase gene. The transcription initiation sites of both the human and rat genes were determined by primer extension and S1 nuclease protection analyses. Comparison of the 5'-flanking regions of the human and rat genes revealed three extended regions of high sequence similarity, one of which includes a potential TATA box and other basic promoter elements beginning about 30 nucleotides upstream of the transcription start site. Other conserved sequences, including possible response elements for Ca2+ and cAMP, which are known intracellular mediators of acid secretion, are located up to 2 kb 5' to the transcription initiation site.

Bladder contributes to eicosanoids excreted in urine

The excretion of eicosanoids was examined in urine collected from the bladder or the ureter in normal rats. We found that the excretion of thromboxane B2 (the stable metabolite of thromboxane A2), prostaglandin E2, and 6-ketoprostaglandin F1 alpha was significantly greater in urine collected from the bladder than in urine collected from the ureter. This suggests that the bladder contributes significantly to the amount of eicosanoids present in the urine.

Structural requirements for neural cell adhesion molecule-heparin interaction

Two biological domains have been identified in the amino terminal region of the neural cell adhesion molecule (NCAM): a homophilic-binding domain, responsible for NCAM-NCAM interactions, and a heparin-binding domain (HBD). It is not known whether these two domains exist as distinct structural entities in the NCAM molecule. To approach this question, we have further defined the relationship between NCAM-heparin binding and cell adhesion. A putative HBD consisting of two clusters of basic amino acid residues located close to each other in the linear amino acid sequence of NCAM has previously been identified. Synthetic peptides corresponding to this domain were shown to bind both heparin and retinal cells. Here we report the construction of NCAM cDNAs with targeted mutations in the HBD. Mouse fibroblast cells transfected with the mutant cDNAs express NCAM polypeptides with altered HBD (NCAM-102 and NCAM-104) or deleted HBD (HBD-) at levels similar to those of wild-type NCAM. Mutant NCAM polypeptides purified from transfected cell lines have substantially reduced binding to heparin and fail to promote chick retinal cell attachment. Furthermore, whereas a synthetic peptide that contains both basic amino acid clusters inhibits retinal-cell adhesion to NCAM-coated dishes, synthetic peptides in which either one of the two basic regions is altered to contain only neutral amino acids do not inhibit this adhesion. These results confirm that this region of the NCAM polypeptide does indeed mediate not only the large majority of NCAM's affinity for heparin but also a significant portion of the cell-adhesion-mediating capability of NCAM.

A high cholesterol diet ameliorates renal tubular lesions in diabetic rats

These studies examine the effect of cholesterol feeding in normal rats and in rats with streptozotocin-induced diabetes mellitus. Four groups were studied: normal rats fed either a standard rat chow or a standard rat chow supplemented with cholesterol and diabetic rats fed standard chow or standard chow plus cholesterol. Diabetic rats fed a standard diet excreted more creatinine and urea in the urine, had higher levels of blood urea nitrogen, and lower serum albumin levels than rats fed standard diet plus cholesterol. Blood glucose levels were similar in the two groups; however, diabetic rats given cholesterol had a greater body weight at the end of the study than diabetic rats eating standard chow. Urine volumes and sodium and potassium excretion in the urine were greater in diabetic rats fed a standard diet than in those fed a high cholesterol diet. Diabetic rats fed a standard diet had distinctive renal lesions characterized by swelling of tubular epithelial cells with clearing of cytoplasm. The nephron segments involved by this striking vacuolar change were the distal convoluted tubule and the thick limbs of Henle's loop. These lesions were identical to those described by Armanni-Ebstein in severely glycosuric patients. These lesions were not observed in any of the animals of the other three groups (including diabetic rats fed a high cholesterol diet). Glomeruli were normal in animals of all groups. Thus, cholesterol administration prevents the development of the Armanni-Ebstein lesions in diabetic rats despite persistent hyperglycemia. The mechanism by which cholesterol administration prevents the accumulation of glycogen in distal tubule cells has not been elucidated. It is suggested that glycogen accumulation in distal tubular segments may explain the greater urine volumes, natriuresis, kaliuresis, and proteinuria observed in diabetic animals fed a standard diet when compared with rats fed the same diet plus cholesterol.

Generation of multiple independent substitution mutants by M13 in vitro mutagenesis using a single mutagenic oligonucleotide

A 56-nucleotide mutagenic oligomer containing six mismatches with the wild-type template was used to construct multiple transversion mutations in the putative heparin binding region of the rat neural cell adhesion molecule (NCAM) cDNA sequence. Mutants were screened by hybridization to the 56-mer. The relative stability of a mutant DNA:56-mer duplex correlated with the number of base substitutions present in the mutant sequence. Five independent categories of mutants carrying from two to five of the expected nucleotide substitutions were isolated. No mutations other than those directed by the 56-mer were observed. These results suggest a method for generating sets of related predefined substitution mutants.

Cardiovascular effects and safety of dental anesthesia and dental interventions in patients with recent uncomplicated myocardial infarction

To determine the cardiovascular effects and safety of dental anesthesia and dental interventions in patients within three weeks of uncomplicated acute myocardial infarction, 40 patients were studied. Twenty patients, group 1, underwent injectable local dental anesthesia with 2% lidocaine and 1:100 000 epinephrine. Group 2, 20 patients, underwent vigorous dental prophylaxis (13 patients) or dental extraction (seven patients) after local anesthesia. Heart rate, blood pressure, electrocardiograms, and symptoms were monitored before, during, and after the dental intervention. There were no significant hemodynamic changes or complications related to dental anesthesia or the dental procedures. One patient experienced an asymptomatic, uncomplicated, self-limited, eight-beat run of ventricular tachycardia two hours after dental extraction. Limited dental anesthesia and dental interventions were well tolerated by these patients with recent myocardial infarction.

Evidence that polymorphism in the murine major histocompatibility complex may be generated by the assortment of subgene sequences

The high degree of polymorphism found among the class I genes of the murine major histocompatibility complex (H-2) has led to the postulation that specific genetic mechanisms are responsible for their diversity. These same genetic mechanisms are probably responsible for the high spontaneous mutation frequency seen in H-2 alleles. The bml mutation of the H-2Kb gene has been shown to be 7 base pair changes over a 13 base pair region that result in three amino acid substitutions in the C1 domain of the protein product. The clustering of base-pair changes has suggested that the bm1 mutation resulted from a recombinational event analogous to gene conversion between the H-2Kb gene and a "donor" gene sequence. A 23-base oligonucleotide complementary to the bm1 mutant sequences was synthesized and used to probe genomic DNA restriction digests of the parental H-2b haplotype as well as other H-2 haplotypes. Our results indicate that a potential donor gene sequence is present in the genomes of all of the five mouse strains studied. Of eight tissues that were tested by blot-hybridization analysis, the potential donor gene sequences are transcribed only in the liver. Models for the generation of polymorphism among the H-2 class I genes via subgene rearrangements are proposed.

Oligonucleotide-directed mutagenesis using plasmid DNA templates and two primers

Oligonucleotide-directed mutagenesis using plasmid vectors has been simplified by introducing two changes to the previous method. First, template preparation has been simplified by using the covalently closed circular plasmid DNA directly for mutagenesis, eliminating the need for a wholly or partially single-stranded circular DNA template. Second, two primers are used, eliminating the need for producing the covalently closed molecule during in vitro replication. The advantages of the approach are discussed.

Comparison of the cloned H-2Kbm1 variant gene with the H-2Kb gene shows a cluster of seven nucleotide differences

The gene for the H-2K class I antigen of the bm1 variant was cloned and analyzed at the DNA level and compared with the previously cloned parent B6/Kh gene. Sequence determination and comparative restriction endonuclease studies indicate that Kbm1 is derived from the Kb gene. Seven nucleotide changes within a 13-nucleotide stretch distinguish the mutant from the parent gene and result in amino acid differences at positions 152, 155, and 156 in the antigen. The data confirm previously reported changes at amino acid positions 155 and 156 (arginine to tyrosine and leucine to tyrosine, respectively) and extend the altered region to include two nucleotides encoding a glutamate to alanine substitution at amino acid 152, a change not detected by the protein studies because of limitations of the methods used. The DNA sequence encoding this region of the Kbm1 glycoprotein is identical to the DNA sequence of at least one other known class I gene in the mouse, a finding consistent with the hypothesis that the mutation was not a random event but may be the result of a block transfer of information by a copy mechanism analogous to gene conversion. As the sequence analysis of the coding region for the first 273 amino acid residues shows identity between parent and mutant except for the seven nucleotide changes, all variant-parent functional differences must depend only on the cluster of three amino acid differences in the second domain of the Kb glycoprotein.

Identification of the cloned gene for the murine transplantation antigen H-2Kb by hybridization with synthetic oligonucleotides

The H-2K(b) gene is a member of the large major histocompatibility complex class I gene family. Since many members of this family cross-hybridize with class I cDNA probes, the cloned H-2K(b) gene was identified by hybridization with specific oligonucleotide probes. This clone was definitively shown to encode the H-2K(b) polypeptide by partial DNA sequencing and by serological and tryptic peptide analyses of the expressed product.

Detection of sickle cell beta S-globin allele by hybridization with synthetic oligonucleotides

Two 19-base-long oligonucleotides were synthesized, one complementary to the normal human beta-globin gene (beta A) and one complementary to the sickle cell beta-globin gene (beta S). The nonadecanucleotides were radioactively labeled and used as probes in DNA hybridization. Under appropriate hybridization conditions, these probes can be used to distinguish the beta A gene from the beta S allele. The DNA from individuals homozygous for the normal beta-globin gene (beta A beta A) only hybridized with the beta A specific probe; the DNA from those homozygous for the sickle cell beta-globin gene (beta S beta S) only hybridized with the beta S specific probe. The DNA from heterozygous individuals (beta A beta S) hybridized with both probes. This allele-specific hybridization behavior of oligonucleotides provides a general method for diagnosis of any genetic disease which involves a point mutation in the DNA sequence of a single-copy gene.

Isolation of a cDNA clone for the murine transplantation antigen H-2Kb

A library of cloned cDNAs constructed from the poly(A)+RNA of the murine thymoma cell line EL4 (b haplotype) was screened with a probe encoding a short region of the H-2Kb transplantation antigen. One of the clones isolated, pH202, contains a region that can code for a transplantation antigen with an amino acid sequence 98% homologous to that previously published for H-2Kb. Based on this high degree of homology, pH202 appears to encode the H-2Kb antigen from amino acid 66 through the carboxy terminus, including 386 nucleotides of 3'-untranslated sequence. The amino acid sequence deduced from pH202 suggests that the H-2Kb antigen is actually 2 amino acids longer than previously reported (a total of 348 residues). Four other differences in amino acid assignments are seen. Analysis of the DNA sequences of pH202 and other H-2 clones previously described in the literature suggests that alternative routes of splicing at the 3' end of the coding region are involved in the production of different transplantation antigen mRNAs.

The complete amino acid sequence of the murine transplantation antigen H-2Db as deduced by molecular cloning

A mouse cDNA library derived from the EL4 cell line (b-haplotype) was screened with a probe containing a small part of the H-2Kb coding region. One of the clones isolated, pH203, encodes a protein whose deduced amino acid sequence is identical with the known sequence of H-2Db in 141 of 141 positions available for comparison. The clone, therefore, is believed to code for the H-2Db transplantation antigen. The cDNA insert of pH203 contains the coding region for residues 82 through the carboxy-terminus of H-2Db, and includes 476 nucleotides of the 3'-untranslated sequence. Comparison between the H-2Db cDNA clone and a previously isolated H-2Kb cDNA clone shows homologies of 83% and 91% at the amino acid and nucleotide levels, respectively. Analysis of DNA sequences at the 3'-coding and untranslated regions suggests that the mRNAs of H-2Kb and H-2Db are spliced differently at their 3'-coding ends.

Identification of an H-2Kb-related molecule by molecular cloning

Based on the published amino-acid sequence of H-2Kb, we synthesized a mixture of eight 16-base long oligodeoxyribonucleotides representing all possible coding sequences for residues 51-56 (Trp-Met-Glu-Gln-Glu-Gly). The hexadecanucleotide mixture was used as a probe to screen recombinant DNA clones constructed from cytoplasmic PolyA+ RNA isolated from the murine thymoma cell line EL4(b haplotype). Of the 30 000 independent clones screened, one clone was found to hybridize with the probe. DNA sequence analysis showed that the cDNA clone was derived from a portion of an H-2Kb -related mRNA. The clone encodes a protein sequence identical with a region of H-2Kb in 42 consecutive residues (50 through 91). The sequence than diverges from the H-2Kb sequence and, after a single Glu codon, a termination codon is encountered. It is possible that this mRNA codes for a small 92 amino-acid protein with a sequence identical (except for a carboxy-terminal Glu residue) with the amino terminus of H-2Kb. It is further speculated that this mRNA is coded for by the H-2Kb gene and differs from the H-2Kb mRNA in the pattern of posttranscriptional splicing.

The rat serum albumin gene: analysis of cloned sequences

The rat serum albumin gene has been isolated from a recombinant library containing the entire rat genome cloned in the lambda phage Charon 4A. Preliminary R-loop and restriction analysis has revealed that this gene is split into at least 14 fragments (exons) by 13 intervening sequences (introns), and that it occupies a minimum of 14.5 kilobases of genomic DNA.

Populations of the spinach wilt pathogen, Fusarium oxysporum f. sp. spinaciae, in the root tissues, rhizosphere, and soil in the field

Populations of Fusarium oxysporum f. sp. spinaciae in root tissues and rhizosphere soil of diseased spinach plants were higher than in the root tissues and rhizosphere soil of healthy plants. Populations in soil rhizosphere were higher than in nonrhizosphere soil. The fungus populations were very low in the root tissues of the nonsusceptible strawberry, broccoli, chinese cabbage, and mustard grown in the infested field. The populations were low at the beginning of the season, increased, and remained high during the summer, then dropped in the fall. The fungus populations ranged from 1600 to 2600 propagules/g in the top 10 cm of soil, declined sharply between 11 and 20 cm, and were nondetectable between 41 and 60 cm.