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J M Becker

Publications and source records attributed to J M Becker.

At least 127 records · Page 7Linked to original sources
PubMed1990

Internalization of lucifer yellow in Candida albicans by fluid phase endocytosis.

Lucifer yellow (LY), an impermeable fluorescent dye used as a marker for fluid phase endocytosis, was internalized by Candida albicans. As observed by fluorescence microscopy, incubation of C. albicans with LY in potassium phosphate buffer (pH 6.0) and glucose (2%, w/v) resulted in localization of the dye inside vacuoles. Sodium azide and carbonyl cyanide m-chlorophenylhydrazone, which are inhibitors of energy metabolism, decreased the uptake of the dye. The optimum temperature for uptake was 30 degrees C; no internalization was observed at 0 degrees C. Quantification of cell-associated LY by fluorescence spectrometry showed an uptake linear with time and not saturable over a 400-fold range of concentration. Thus, C. albicans internalized LY into vacuoles by a nonsaturable and time-, temperature- and energy-dependent process consistent with fluid phase endocytosis. Both the yeast and mould phase of this dimorphic fungus endocytosed LY. Growth in complex medium appeared to be required to enable the cells to internalize LY. However, addition of peptone or yeast extract to the phosphate buffer/glucose assay medium interfered with LY uptake by causing an apparent increase of exocytosis. These studies provide the first evidence of fluid phase endocytosis in C. albicans and may explain how some large molecules, such as toxins and cationic proteins, enter C. albicans.

Candida albicans↗
PubMed1990

Synthesis of biologically active analogs of the dodecapeptide a-factor mating pheromone of Saccharomyces cerevisiae.

A number of dodecapeptides with the sequence YIIKGVFWDPAC were synthesized using solid phase peptide synthesis. The purity of the crude cleavage product was found to be directly related to the cysteine protecting group and the conditions employed for cleavage of the peptide from the resin. When 4-methyl-benzyl cysteine was used, complete deprotection was only achieved with low-high HF conditions at temperatures of 10 degrees-25 degrees, whereas milder conditions could be used for dodecapeptides containing ethyl cysteine or acetamidomethyl cysteine. In several syntheses the biological activity of the crude cleavage product greatly exceeded the biological activity of a purified major peptide component. The high activity found in the crude cleavage peptide was probably due to minor peptide side products in which the cysteine sulfur was alkylated by hydrophobic species during HF treatment. Two dodecapeptides, YIIKGVFWDPAC and YIIKGFWDPAC(Ethyl), had significant a-factor activity against MAT alpha strains of Saccharomyces cerevisiae. These peptides represent the first synthetic analogs with a-factor activity.

Amino Acid Sequence↗
PubMed1990

Solution phase synthesis of Saccharomyces cerevisiae a-mating factor and its analogs.

The solution phase synthesis of the Saccharomyces cerevisiae a-mating factor and nonfarnesylated and nonmethylated a-factor analogs are reported. The a-factor, a lipopeptide with the sequence Tyr-Ile-Ile-Lys-Gly-Val-Phe-Trp-Asp-Pro-Ala-Cys(S-Farnesyl)OCH3 was synthesized by the condensation of the amine terminal protected decapeptide with the carboxyl terminal farnesylated dipeptide using benzotriazol-l-yloxy-tris-(dimethylamino)-phosphonium hexafluorophosphate (BOP reagent) as the coupling agent. The synthesis of the decapeptide involved 5 + 5 fragment coupling with the BOP reagent and the successful application of 9-fluorenylmethyl ester(OFm) and 9-fluorenylmethoxycarbonyl(Fmoc) groups for the protection of Asp and Lys side chains and Tyr alpha-amine and of phenacyl esters (OPa) for alpha-carboxyl protection. The OFm and Fmoc groups tolerated repeated couplings and were completely stable to zinc powder in acetic acid, a condition under which the OPa group was removed. The synthesis of the nonfarnesylated alpha-factor was accomplished by the coupling of the decapeptide with tetrapeptide (Ala-CysOCH3)2 followed by the deprotection of the OFm and Fmoc groups with piperidine and the cleavage of the disulfide bond with zinc powder in acetic acid. The nonmethylated a-factor was prepared by 10 + 2 fragment coupling using OFm protection of the dipeptide carboxyl group followed by removal of all protecting groups with piperidine. Attempts to saponify a-factor were not successful. The synthetic nonfarnesylated and nonmethylated a-mating pheromones were 100-1000 times less active than the a-factor, indicating that although the methyl ester and the farnesyl group are not essential for biological activity, they are necessary for high potency.

Amino Acid Sequence↗
PubMed1990

Ileal J pouch: radiologic evaluation in patients with and without postoperative infectious complications.

The authors studied the ileograms and computed tomographic (CT) examinations of 18 patients who had undergone surgical construction of an ileal J pouch and ileoanal anastomosis; 10 had developed postoperative infectious complications and eight had not. The initial ileograms obtained 4 weeks postoperatively proved to be unhelpful in predicting future infectious complications, showing abnormalities in only two of 10 patients. Ileography and CT performed at the time of the complications showed abnormalities in eight of nine and nine of 10 patients, respectively. Ileographic abnormalities in patients with abscesses included extravasation of contrast material, extraluminal gas collections, thickening of ileal pouch folds, and extrinsic mass effect on the pouch. CT findings included thickening of the pouch and/or rectal walls, streaky areas of soft-tissue attenuation within the ileal pouch mesentery and perirectal fat, and areas of soft-tissue attenuation or fluid attenuation in the peripouch region. CT was more valuable in depicting the site and extent of abscess formation before surgical or percutaneous drainage.

Adenomatous Polyposis Coli↗
PubMed1990

Time-series analysis of myoelectric cycling of sphincter of Oddi: evidence of cycling during fed state.

The sphincter of Oddi (SO) in the fasted opossum exhibits spontaneous cyclic spikeburst activity that is temporally related to the interdigestive migrating myoelectric complex (MMC) of the small intestine. After feeding, the cyclic activity is apparently disrupted. Our aim was to use time-series analysis to mathematically describe the periodic behavior of the fasted state and to determine whether this periodicity is present after feeding. Five opossums were chronically prepared with bipolar electrodes secured to the SO. With the animals fasted and conscious, myoelectric activity was recorded for at least two MMC cycles after which they were fed 170 kcal of cream. Spikeburst frequency data were analyzed by fast Fourier transform (FFT) and by digital band-pass filtering. Results from FFT analysis showed an intense low-frequency peak during the fasted state which persisted but was markedly depressed during the fed state. Analysis of the data after filtering also showed persistent sinusoidal activity at the MMC frequency after feeding, although the waveform was significantly depressed by both peak-to-peak amplitude and root mean square amplitude analysis. Recovery to normal fasting cyclic behavior with recovery of both FFT and filtered data was observed. We conclude that in the opossum the cyclic nature of the SO myoelectric activity observed during the fasted state persists after feeding, but is inhibited and masked by an increase in overall spikeburst activity.

Ampulla of Vater↗
PubMed1990

[The treatment of imported Plasmodium falciparum malaria with halofantrine. Apropos of 59 case reports (corrected and republished article orginally printed in Med Trop (Mars) 1990 Jan-Mar;50(1):113-7)].

59 cases of Plasmodium falciparum malaria fever occurring in non-immune Caucasian subjects having got a correct chemoprophylaxis by chloroquine were treated by halofantrine (HALFAN). They were given 1500 mg divided in 3 doses of 500 mg every 6 hours from D1 to D8. All them were back from a malarial highly endemic zone with chloroquine resistance. Analysis of the main biological and clinical efficiency parameters displayed very satisfactory results: disappearances of fever (mean 22 H) and parasitemia (mean 36 H) are short. After two months of monitoring, no malaria recrudescence was noted. With an efficacy of 10 p.c. associated to a noticeable clinical and biological tolerance Halofantrine is a first-class treatment of chloroquine resistant malaria fever.

Adolescent↗
PubMed1989

A covalently constrained congener of the Saccharomyces cerevisiae tridecapeptide mating pheromone is an agonist.

An analog of alpha-factor, the Saccharomyces cerevisiae tridecapeptide mating pheromone (Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr), in which the side chains of Lys7 and Gln10 were covalently linked, was synthesized using solid phase methodologies. The yield of the purified cyclic analog cyclo7,10[Nle12]alpha-factor was 30%, and its structure was verified by amino acid analysis, peptide sequencing, fast atom bombardment-mass spectrometry, and proton nuclear magnetic resonance spectroscopy. Cyclo7,10[Nle12]alpha-factor caused growth arrest and morphological alterations in S. cerevisiae MATa cells qualitatively identical to those induced by linear pheromone and was one-fourth to one-twentieth as active as the linear alpha-factor depending upon the S. cerevisiae strain tested. Consistent with the relative activities of the linear and cyclic peptides, binding competition studies indicated that cyclo7,10[Nle12]alpha-factor had approximately 20-40-fold less affinity for the alpha-factor receptor. Hydrolysis of the cyclic peptide by the target cells did not lead to opening of the ring and was less rapid than that of linear alpha-factor. The alpha-factor antagonist des-Trp1-[Ala3,Nle12]alpha-factor reversed the activity of the cyclic analog, and cyclo7,10[Nle12]alpha-factor was not active at the restrictive temperature in a temperature-sensitive receptor mutant. These results support the conclusion that the cyclic alpha-factor occupies the same binding site within the receptor as is occupied by the natural pheromone. The cyclic alpha-factor represents a rare example of an agonist among covalently constrained congeners of small linear peptide messengers.

Amino Acid Sequence↗
PubMed1989

Total synthesis of the lipopeptide a-mating factor of Saccharomyces cerevisiae.

The a-mating factor of Saccharomyces cerevisiae was synthesized using both solution phase and solid phase strategies. Structure of the final peptide was confirmed using amino acid analysis, fast atom bombardment mass spectroscopy and 400 MHz proton NMR. The synthetic farnesylated dodecapeptide, YIIKGVFWDPAC (S-farnesyl) OCH3, exhibited chromatographic and spectroscopic properties identical to the natural pheromone and had significant biological activity at nanomolar concentrations.

Acetates↗
PubMed1989

Interaction of the Saccharomyces cerevisiae alpha-factor with phospholipid vesicles as revealed by proton and phosphorus NMR.

Proton and phosphorus-31 nuclear magnetic resonance (1H and 31P NMR) studies of the interaction between a tridecapeptide pheromone, the alpha-factor of Saccharomyces cerevisiae, and sonicated lipid vesicles are reported. 31P NMR studies demonstrate that there is interaction of the peptide with the phosphorus headgroups, and quasielastic light scattering (QLS) studies indicate that lipid vesicles increase in size upon addition of peptide. Previous solution (aqueous and DMSO) studies from this laboratory indicate that alpha-factor is highly flexible with only one long-lived identifiable structural feature, a type II beta-turn spanning the central portion of the peptide. Two-dimensional (2D) 1H nuclear Overhauser effect spectroscopy (NOESY) studies demonstrate a marked ordering of the peptide upon interaction with lipid, suggesting a compact N-terminus, in addition to a stabilized beta-turn. In contrast to our results in both solution and lipid environment, Wakamatsu et al. [Wakamatsu, K., Okada, A., Suzuki, M., Higashijima, T., Masui, Y., Sakakibara, S., & Miyazawa, T. (1986) Eur. J. Biochem. 154, 607-615] proposed a lipid environment conformation, on the basis of one-dimensional transferred NOE studies in D2O, which does not include the beta-turn.

Binding Sites↗
PubMed1989

Regulation of hemopoiesis in myelosuppressed mice by human recombinant IL-1 alpha.

Human rIL-1 alpha was shown to be a potent stimulus of granulopoiesis in mice that have been myelosuppressed with cyclophosphamide. Stimulation of granulopoiesis was demonstrated in IL-1-treated mice by an accelerated recovery of granulocyte-macrophage colony-forming cells, bone marrow and splenic granulocytic hyperplasia, and a profound granulocytosis. Granulopoiesis was stimulated by IL-1 in a dose-dependent manner at doses ranging from 0.5 to 50 micrograms/kg. Maximal increases in granulocytes were observed after 4 days of IL-1 treatment. Mice treated with IL-1 also exhibited increased splenic megakaryopoiesis with a resultant increase in the number of peripheral blood platelets. In contrast to these positive effects on hemopoiesis, bone marrow, but not splenic, erythropoiesis was depressed in IL-1-treated mice. IL-1 effects were observed in mice treated with a wide dose range (50 to 300 mg/kg) of cyclophosphamide, with optimal effects occurring at a dose of 200 mg/kg. The doses of IL-1 leading to enhanced granulopoiesis caused only minor and transient changes in selected clinical chemistry parameters and caused no toxicities that were evident by histologic examination of tissues. The stimulation of granulopoiesis in the absence of overt toxicity suggests that IL-1 may be useful clinically to enhance the recovery of granulocytes in myelosuppressed patients.

Animals↗
PubMed1989

Successful surgical treatment of idiopathic colonic dysmotility. The role of preoperative evaluation of coloanal motor function.

Identification of patients with severe idiopathic colonic dysmotility who would benefit from surgery can be difficult. Colonic transit studies and anorectal manometry were applied to 12 women with severe constipation before subtotal colectomy. Delayed transit was noted in all patients with most exhibiting left-sided colonic arrest. Mean anal resting pressure and rectal capacity were similar to that in healthy controls. Pathologic examination results revealed decreased argyrophilic neurons in the colonic myenteric plexus. At 24 months postoperatively, all patients were satisfied with their results and mean (+/- SEM) weekly bowel movement frequency was 17 +/- 3 (compared with 0.8 +/- 0.2 preoperatively). Preoperative coloanal function studies therefore aid in the selection of patients who will be successfully treated by surgery. Subtotal colectomy with ileorectal anastomosis is the preferred operation because dysmotility can originate from either side of the colon.

Adult↗
PubMed1989

Biologically significant conformation of the Saccharomyces cerevisiae alpha-factor.

The conformation of the tridecapeptide alpha-factor of the yeast Saccharomyces cerevisiae was examined in both solution and in the presence of lipid vesicles. CD, differential scanning calorimetry, and phosphorus nmr all indicate that this mating pheromone interacts with lipid vesicles. In both aqueous and organic solution the alpha-factor is a flexible molecule that exhibits features of a type II beta-turn spanning the center of the peptide. Two-dimensional Nuclear Overhauser enhancement spectroscopy gives evidence that the beta-turn is stabilized on interaction of the peptide with lipid vesicles. Our current belief is that the beta-turn may play an important role in the biologically active conformation of the alpha-factor.

Mating Factor↗
PubMed1989

Anterior lesser curvature laser seromyotomy with posterior truncal vagotomy: a potential treatment of peptic ulcer disease.

Anterior lesser curvature seromyotomy combined with posterior truncal vagotomy has been suggested as an alternative to proximal gastric vagotomy in the treatment of peptic ulcer. The argon laser may be an ideal instrument for performing seromyotomy. This study compares anterior lesser curvature argon laser seromyotomy/posterior or truncal vagotomy with anterior proximal gastric vagotomy/posterior truncal vagotomy in a canine preparation. Six dogs underwent anterior lesser curvature argon laser seromyotomy/posterior truncal vagotomy and six others underwent anterior proximal gastric vagotomy/posterior truncal vagotomy. Gastric emptying and acid secretion studies were performed preoperatively and at 1 and 6 months postoperatively. Operating time and blood loss were determined. Anterior lesser curvature argon laser seromyotomy was performed with the argon laser at 10 W, continuous, delivered through a 600 micron unsheathed quartz fibre. Anterior proximal gastric vagotomy and posterior truncal vagotomy were performed in the standard fashion. Solid phase gastric emptying was slowed with both operations (P less than 0.05) but this was not manifest clinically. Blood loss (millilitres) was less following anterior lesser curvature argon laser seromyotomy/posterior truncal vagotomy than following anterior proximal gastric vagotomy/posterior truncal vagotomy (21(6.8) versus 95(28.1), mean (s.e.m.), P less than 0.05) but operating time was not significantly different between the groups. Mean basal acid secretion was reduced by 64 per cent 6 months after anterior lesser, curvature argon laser seromyotomy/posterior truncal vagotomy (P less than 0.05) and by 53 per cent after anterior proximal gastric vagotomy/posterior truncal vagotomy (not significant). Mean stimulated acid secretion was reduced by 41 per cent 6 months after anterior lesser curvature argon laser seromyotomy/posterior truncal vagotomy (P less than 0.05) and by 24 per cent after anterior proximal gastric vagotomy/posterior truncal vagotomy (not significant). We conclude that anterior lesser curvature argon laser seromyotomy/posterior truncal vagotomy is an acceptable alternative to anterior proximal gastric vagotomy/posterior truncal vagotomy and may provide superior parietal cell denervation with less operative blood loss.

Animals↗
PubMed1989

Gastrocolic fistula as a complication of benign gastric ulcer: report of four cases and update of the literature.

Four cases of gastrocolic fistula complicating benign gastric ulcer are described, bringing the total number of individually reviewed cases in the English language literature to 108. A review of 30 cases reported in the past 10 years reveals a surprisingly high percentage of young, female patients. Three-quarters of these patients used steroidal or nonsteroidal anti-inflammatory agents. The presence of such fistulae is suspected in patients complaining of weight loss, diarrhoea and faecal vomiting. Small fistulae may not be suspected when overshadowed by other complications of ulcer disease such as bleeding or perforated viscus. Medical management of benign gastrocolic fistulae may be indicated in some circumstances. Surgical treatment involves en bloc resection, including the fistula, and surrounding colon and gastric segments.

Adult↗
PubMed1989

High prevalence of adenomatous polyps of the duodenal papilla in familial adenomatous polyposis.

Eighteen consecutive asymptomatic patients with familial adenomatous polyposis (both familial polyposis coli and Gardener's syndrome) were studied over a 12-month period; side-viewing upper endoscopy and biopsy were used to assess the frequency of adenomatous polyps of the duodenal papilla. Nine of the 18 patients demonstrated adenomatous polyps of the papilla, varying in size and appearance from microadenomas in normal-appearing duodenal papillae (two) to a sessile polyp 3 cm in diameter. Two were tubulovillous adenomas (0.5 cm and 2 cm in diameter) and the remainder were tubular adenomas. Severe atypia and malignancy were not encountered. These findings reveal that adenomas of the duodenal papilla are common in individuals with familial adenomatous polyposis. Because of these findings and because of the known risk of periampullary adenocarcinomas and nonmalignant complications of polyps of the duodenal papilla in patients with familial adenomatous polyposis, upper gastrointestinal screening of such patients should include examination of the duodenal papilla with a side-viewing endoscope.

Adenomatous Polyposis Coli↗
PubMed1989

Characterization of substance P effects on sphincter of Oddi myoelectric activity.

We examined the effects of substance P (SP) on the myoelectric activity of the opossum sphincter of Oddi (SO). Myoelectric data from the SO in five adult opossums were recorded using thin stainless steel electrodes and computer-assisted analog-to-digital conversion. In fully awake and conscious animals, baseline spikeburst activity during phase I of the MMC occurred at a frequency of 28.6 +/- 3.1 spikebursts (SB) per 20-min period. Intravenous infusion of graded doses of substance P (from 0.5 to 8.0 micrograms/kg) stimulated SO myoelectric activity in a dose-related manner (from 80 +/- 8 to 235 +/- 11 SB/20 min, respectively, P less than 0.05 when compared to baseline). The effect of substance P on SO myoelectric activity was antagonized by administration of the H2-blocker, cimetidine (92.0 +/- 6.1 vs 48.2 +/- 7.0, n = 5, P less than 0.05). Administration of the antimuscarinic drug atropine only slightly affected the SO spikeburst frequency when infused prior to SP (73.0 +/- 10.4 vs 70.8 +/- 8.2, P greater than 0.05). We conclude that SP stimulated the SO spikeburst frequency in a dose-dependent fashion. Cimetidine markedly inhibited the response of the SO to SP but atropine did not. The excitatory effect of substance P on the opossum SO is mediated at least in part by a histaminergic, noncholinergic pathway.

Ampulla of Vater↗
PubMed1989

Cytomorphometry of osteoclasts.

Tartrate resistant acid phosphatase (TRAP) is considered as an enzyme marker for osteoclasts and their precursors. A cytomorphometric study of the osteoclastic population was made after TRAP staining on transiliac bone biopsies from 10 human volunteers, and the diameter of each TRAP positive profile was determined with an automatic image analyser. The frequency distribution of the cell diameter followed a lognormal law. TRAP positive cells along bone trabeculae belong to a homogeneous osteoclastic population.

Acid Phosphatase↗