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Biomedical subjects

D M Sherman

Publications and source records attributed to D M Sherman.

At least 19 recordsLinked to original sources
PubMed2003

Expression of cellular antigens of Listeria monocytogenes that react with monoclonal antibodies C11E9 and EM-7G1 under acid-, salt- or temperature-induced stress environments.

AIMS: To study the expression of cellular antigens of Listeria monocytogenes that react with monoclonal antibodies (MAbs) C11E9 and EM-7G1 under acid-, salt- or temperature-induced stress environments. METHODS AND RESULTS: The reaction patterns of antibodies to L. monocytogenes held in stressful environments for a short duration (3 h) or grown for extended periods (16-72 h) were investigated. During both short or prolonged exposure to stress environments of high temperature (45 degrees C) and NaCl (>1.5%, w/v), reactions of whole cells of L. monocytogenes to antibodies were severely affected as determined by ELISA and by the reduced expression of the antibody-reactive 66 kDa antigen in the Western blot assay. Conversely, cold (4-15 degrees C) or acid (pH 2-3) stress environments had very little effect on antigen expression or antibody reaction. Additionally, heat-killed cells showed reduced reactions to these antibodies when compared with unheated cells. Artificially created stress environments in hotdog slurry also affected the antigen expression in L. monocytogenes. Immunoelectron microscopy revealed that the antibody-reactive antigens were uniformly present on the surface of the cells. Morphological characteristics following growth in stressed environments revealed that heat stress at 45 degrees C caused L. monocytogenes cells to be elongated and to form clumps; whereas, osmotic stress (5.5% NaCl, w/v) caused filamentous appearance with multiple septa along the length of the cell. CONCLUSIONS: These results indicated that MAb C11E9 or EM-7G1 could detect L. monocytogenes from cold or acid-stress environments; however, they may show weaker reactions with heat or osmotically stressed cells or cells grown at 4 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacteria in food are routinely subjected to various stresses, induced by cold, heat, salt or acid during processing and storage. Whether stresses would modify the expression of cellular antigens of L. monocytogenes is of a great concern for immunodetections in food products.

Antibodies, Monoclonal↗
PubMed2001

Pattern of cyanophycin accumulation in nitrogen-fixing and non-nitrogen-fixing cyanobacteria.

The temporal and spatial accumulation of cyanophycin was studied in two unicellular strains of cyanobacteria, the diazotrophic Cyanothece sp. strain ATCC 51142 and the non-diazotrophic Synechocystis sp. strain PCC 6803. Biochemistry and electron microscopy were used to monitor the dynamics of cyanophycin accumulation under nitrogen-sufficient and nitrogen-deficient conditions. In Cyanothece sp. ATCC 51142 grown under 12 h light/12 h dark nitrogen-fixing conditions, cyanophycin was temporally regulated relative to nitrogenase activity and accumulated in granules after nitrogenase activity commenced. Cyanophycin granules reached a maximum after the peak of nitrogenase activity and eventually were utilized completely. Knock-out mutants were constructed in Synechocystis sp. PCC 6803 cphA and cphB genes to analyze the function of these genes and cyanophycin accumulation under nitrogen-deficient growth conditions. The mutants grew under such conditions, but needed to degrade phycobilisomes as a nitrogen reserve. Granules could be seen in some wild-type cells after treatment with chloramphenicol, but were never found in Delta cphA and Delta cphB mutants. These results led to the conclusion that cyanophycin is temporally and spatially regulated in nitrogen-fixing strains such as Cyanothece sp. ATCC 51142 and represents a key nitrogen reserve in these organisms. However, cyanophycin appeared to play a less important role in the non-diazotrophic unicellular strains and phycobilisomes appeared to be the main nitrogen reserve.

Bacterial Proteins↗
PubMed2001

The efficacy and safety of once-daily Kytril (granisetron hydrochloride) tablets in the prophylaxis of nausea and emesis following fractionated upper abdominal radiotherapy.

This multicenter, randomized, double-blind study compared the efficacy and safety of once-daily oral granisetron 2 mg (n = 134) and placebo (n = 126) as prophylaxis for nausea and emesis in patients receiving upper abdominal fractionated radiotherapy. Patients were scheduled to receive 10-30 fractions of radiotherapy; granisetron (two 1-mg tablets) or placebo was administered 1 hr before radiotherapy on each scheduled treatment day. Treatment comparisons were made at 24 hr and at 10 and 20 fractions. Patients treated with granisetron experienced greater emetic control than those treated with placebo as evidenced by median times to first emesis (35 vs. 9 days, p < 0.001) and first nausea (11 vs. 1 day, p < 0.001). Overall endpoint analysis showed that proportionally more granisetron than placebo patients were emesis free (57.5% vs. 42.1%, p = 0.0047) and nausea free (30.6% vs. 16.7%, p = 0.0042). Furthermore, 25% more granisetron-treated than placebo-treated patients were emesis free and 20% more were nausea free on at least 80% of study treatment days. The most commonly reported adverse experiences in granisetron-treated patients were diarrhea, asthenia, and constipation. These findings demonstrate that a once-daily, 2-mg dose of oral granisetron is well tolerated and significantly more effective than placebo in preventing nausea and emesis induced by fractionated radiotherapy to the upper abdomen.

Abdomen↗
PubMed1998

Structure determination of the phiX174 closed procapsid.

The structure of a procapsid of the single-stranded DNA bacteriophage ++phiX174 was determined to 3.5 A resolution. The crystal space group was I213 with a unit-cell length of 774 A. The unit cell contained 16 icosahedral virus particles, each situated on a crystallographic threefold axis. Thus, there are two independent one-thirds of a particle per asymmetric unit, and a total of 40-fold non-crystallographic redundancy. To aid in the interpretation of the packing arrangement, crystals were prepared for thin sectioning and analyzed by electron microscopy. Oscillation X-ray diffraction data was collected on image plates using synchrotron radiation and oscillation angles of either 0.25 or 0.30 degrees. A low-resolution 6.5 A data set collected from a single frozen crystal was particularly helpful in the structure determination, because of its completeness and internal consistency. The initial particle orientations were determined using self-rotation functions, while the initial position of one particle was determined from a Patterson map. The structure was solved by molecular replacement real-space averaging using a model based on a cryo-electron microscopy reconstruction as a starting point for the phase determination. The initial structure determination used the data between 20 and 13 A resolution, which was then extended one reciprocal lattice point at a time to 6.5 A resolution. At this point, a 3.5 A resolution data set compiled from a number of crystals collected at 277 K was introduced. Phase extension and averaging continued to 3.5 A resolution after re-determining the particle positions and orientations. The amino-acid sequences of most of the D, F and G proteins and part of the B protein could be unambiguously built into the 3.5 A electron-density map. Partial crystallographic refinement yielded an R factor of 31.6%, consistent with the relatively low resolution and lack of completeness of the data.

Bacteriophage phi X 174↗
PubMed1997

Transcriptional and translational regulation of nitrogenase in light-dark- and continuous-light-grown cultures of the unicellular cyanobacterium Cyanothece sp. strain ATCC 51142.

Cyanothece sp. strain ATCC 51142 is a unicellular, diazotrophic cyanobacterium which demonstrated extensive metabolic periodicities of photosynthesis, respiration, and nitrogen fixation when grown under N2-fixing conditions. N2 fixation and respiration peaked at 24-h intervals early in the dark or subjective-dark period, whereas photosynthesis was approximately 12 h out of phase and peaked toward the end of the light or subjective-light phase. Gene regulation studies demonstrated that nitrogenase is carefully controlled at the transcriptional and posttranslational levels. Indeed, Cyanothece sp. strain ATCC 51142 has developed an expensive mode of regulation, such that nitrogenase was synthesized and degraded each day. These patterns were seen when cells were grown under either light-dark or continuous-light conditions. Nitrogenase mRNA was synthesized from the nifHDK operon during the first 4 h of the dark period under light-dark conditions or during the first 6 h of the subjective-dark period when grown in continuous light. The nitrogenase NifH and NifDK subunits reached a maximum level at 4 to 10 h in the dark or subjective-dark periods and were shown by Western blotting and electron microscopy immunocytochemistry to be thoroughly degraded toward the end of the dark periods. An exception is the NifDK protein (MoFe-protein), which appeared not to be completely degraded under continuous-light conditions. We hypothesize that cellular O2 levels were kept low by decreasing photosynthesis and by increasing respiration in the early dark or subjective-dark periods to permit nitrogenase activity. The subsequent increase in O2 levels resulted in nitrogenase damage and eventual degradation.

Cyanobacteria↗
PubMed1995

Mucinous adenocarcinoma of the ovary as a cause of ascites in a goat.

A 6-year-old Nubian doe was evaluated because of slowly progressive abdominal enlargement of 1 month's duration. Five days prior to examination at our hospital, the doe was examined by a local veterinarian. False pregnancy was suspected, and 10 mg of prostaglandin F2 alpha was injected IM. Abdominal distention did not decrease, and the doe did not develop a vaginal discharge. An additional 10 mg of prostaglandin and 24 mg of dexamethasone were injected IM, about 80 hours after the first injection, again without any apparent effect. On arrival at our hospital, the doe was in sternal recumbency and was too weak to stand unassisted. Its abdomen was distended. The body of the uterus and part of 1 uterine horn could be examined by means of transrectal ultrasonography, both appeared normal. The doe was admitted to the hospital, but its condition worsened, and it died during the night. Postmortem examination revealed approximately 30 L of clear, pale, straw-colored fluid in the peritoneal cavity. The caudal pole of the left ovary contained an indistinct, firm, slightly raised, gray-tan mass. The final diagnosis was mucinous adenocarcinoma of the ovary metastatic to the partietal peritoneum, pericardium, and lungs. In adult female goats with bilateral abdominal distention, hydrometra associated with false pregnancy should always be considered; however, if there is no response to prostaglandin administration, distention is more likely to be a result of ascites.

Adenocarcinoma, Mucinous↗
PubMed1994

Osteomyelitis and disseminated infection caused by Corynebacterium renale in a goat.

A 1.5-year-old female goat was examined for recurrence of lameness involving the right forelimb. Radiography of the thorax and right scapulohumeral joint revealed a pathologic fracture of the supraglenoid tubercle, and circumscribed radiolucent lesions in the right third and fourth ribs, and the base of the spinous process of T3. Bone scintigraphy demonstrated additional lesions in the lumbar spine and the wings of the ilium. At necropsy, disseminated infection and hematogenous osteomyelitis were diagnosed. Corynebacterium renale was cultured from the rib lesions. In food animals, osteomyelitis usually develops secondary to traumatic wounds, and members of the genus Actinomyces are frequently incriminated as the causative organism. This case is unusual because the osteomyelitis was unrelated to a traumatic wound, and the gross and microscopic lesions were reminiscent of caseous lymphadenitis, an infection caused by C pseudotuberculosis.

Animals↗
PubMed1994

Oscillating behavior of carbohydrate granule formation and dinitrogen fixation in the cyanobacterium Cyanothece sp. strain ATCC 51142.

It has been shown that some aerobic, unicellular, diazotrophic cyanobacteria temporally separate photosynthetic O2 evolution and oxygen-sensitive N2 fixation. Cyanothece sp. ATCC strain 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that fixes N2 during discrete periods of its cell cycle. When the bacteria are maintained under diurnal light-dark cycles, N2 fixation occurs in the dark. Similar cycling is observed in continuous light, implicating a circadian rhythm. Under N2-fixing conditions, large inclusion granules form between the thylakoid membranes. Maximum granulation, as observed by electron microscopy, occurs before the onset of N2 fixation, and the granules decrease in number during the period of N2 fixation. The granules can be purified from cell homogenates by differential centrifugation. Biochemical analyses of the granules indicate that these structures are primarily carbohydrate, with some protein. Further analyses of the carbohydrate have shown that it is a glucose polymer with some characteristics of glycogen. It is proposed that N2 fixation is driven by energy and reducing power stored in these inclusion granules. Cyanothece sp. strain ATCC 51142 represents an excellent experimental organism for the study of the protective mechanisms of nitrogenase, metabolic events in cyanobacteria under normal and stress conditions, the partitioning of resources between growth and storage, and biological rhythms.

Carbohydrate Metabolism↗
PubMed1994

[The reinfusion of blood and the administration of dalargin in experimental hemorrhagic shock].

In acute experiment on 95 adult rabbits it was determined that during the subdivided blood exfusion from femoral artery in the volume of (16 + 1) ml/kg the reversible hemorrhagic shock occurs and the animals survive without the hemorrhage compensation. The increase of hemorrhage volume up to (23 + 3) ml/kg leads to lethal hemorrhagic shock. The heparinized blood reinfusion in the early period promotes the survival of the whole of animals, in the late period it promotes trustworthy their life span increase. Under the influence of dalargin intravenous infusion in the dose of 0.1 mg/kg after the blood reinfusion in the late period of shock all the animals survived. Intravenous infusion of dalargin is expedient for the increase of the transfusion therapy effectiveness in the late period of hemorrhagic shock.

Animals↗
PubMed1993

Unicellular, aerobic nitrogen-fixing cyanobacteria of the genus Cyanothece.

Two marine, unicellular aerobic nitrogen-fixing cyanobacteria, Cyanothece strain BH63 and Cyanothece strain BH68, were isolated from the intertidal sands of the Texas Gulf coast in enrichment conditions designed to favor rapid growth. By cell morphology, ultrastructure, a GC content of 40%, and aerobic nitrogen fixation ability, these strains were assigned to the genus Cyanothece. These strains can use molecular nitrogen as the sole nitrogen source and are capable of photoheterotrophic growth in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and glycerol. The strains demonstrated a doubling time of 10 to 14 h in the presence of nitrate and 16 to 20 h under nitrogen-fixing conditions. Rapid growth of nitrogen-fixing cultures can be obtained in continuous light even when the cultures are continuously shaken or bubbled with air. Under 12-h alternating light and dark cycles, the aerobic nitrogenase activity was confined to the dark phase. The typical rates of aerobic nitrogenase activity in Cyanothece strains BH63 and BH68 were 1,140 and 1,097 nmol of C2H2 reduced per mg (dry weight) per h, respectively, and nitrogenase activity was stimulated twofold by light. Ultrastructural observations revealed that numerous inclusion granules formed between the photosynthetic membranes in cells grown under nitrogen-fixing conditions. These Cyanothece strains posses many characteristics that make them particularly attractive for a detailed analysis of the interaction of nitrogen fixation and photosynthesis in an aerobic diazotroph.

Bacteria, Aerobic↗
PubMed1992

Immunohistochemical evidence for the presence of oxytocin in the opossum corpus luteum.

Corpora lutea from opossums late in pregnancy were examined by immunohistochemistry for the presence of oxytocin. Oxytocin-immunoreactivity was observed in all corpora lutea examined but not elsewhere in ovarian tissue. The immunoreactive staining observed was confined primarily to the perinuclear cytoplasm of reactive luteal cells. Not all luteal cells showed oxytocin-immunoreactivity. The immunohistochemical localization of oxytocin in the pregnant opossum corpus luteum demonstrates for the first time this peptide in a metatherian ovary. Its presence in this primitive species suggests that oxytocin has a fundamental role in the physiology of the mammalian ovary.

Animals↗
PubMed1992

Immunohistochemical localization of relaxin in the reproductive system of the female opossum (Didelphis virginiana).

Relaxin-immunoreactivity was demonstrated in the cytoplasm in the luteal cells from pregnant and lactating opossums. Immunoreactivity for relaxin was not demonstrated elsewhere in the ovary, in the reproductive tract or in the placenta. The corpus luteum is thought to be the primary source of relaxin in Didelphis and in this regard is similar to several eutherian mammals including man.

Animals↗
PubMed1990

Probable paratuberculosis in a Sicilian ass.

A presumptive diagnosis of paratuberculosis was made in a Sicilian ass on the basis of a history of chronic diarrhea and weight loss, pasture exposure to a heifer with paratuberculosis confirmed by bacterial culture of feces, postmortem identification of granulomatous inflammation of the intestine containing acid-fast organisms, the absence of acid-fast organisms in extraenteric tissues, and the absence of exposure to tuberculosis. The literature on paratuberculosis in equids is reviewed. The potential for cross-species transmission is emphasized. Justification for consideration of Mycobacterium paratuberculosis infection in the differential diagnoses of equine granulomatous enteritis is discussed.

Animals↗
PubMed1990

Immunological characterization of the Prochlorothrix hollandica and Prochloron sp. chlorophyll a/b antenna proteins.

Polyclonal antibodies were prepared against the major antenna chlorophyll (Chl) a/b-binding protein from the prokaryote Prochlorothrix hollandica (Burger-Wiersma et al. (1986) Nature (Lond.) 320, 262-264). Immunoblotting experiments on Triton X-114 phase-partitioned P. hollandica thylakoids revealed that the antibody recognizes intrinsic membrane polypeptides of 33 and 30 kDa, and immunocytochemistry of P. hollandica thin sections showed that the antibody preferentially decorates the thylakoid. The antibody was immunopurified against a LacZ fusion protein produced in Escherichia coli by an immunopositive phage clone retrieved from a lambda ZAP expression library. This purified antibody crossreacted to both the 33 and 30 kDa polypeptides, indicating that these proteins are either structurally related products of different genes, or modified forms of the same gene product. Whereas immunological crossreactivity of Prochlorothrix antibody to the major LHC-II Chl a/b antenna of maize could not be detected, the immunopurified antibody reacted strongly to the major 34 kDa Chl a/b antenna protein from the prokaryote Prochloron sp. (Lewin (1975) Phycologia 14, 153-160). These data confirm the structural similarity of the prochlorophyte photosynthetic antenna systems.

Antibodies↗