Fluctuations in viral load (HCV RNA) are relatively insignificant in untreated patients with chronic HCV infection

A recently available assay to quantify serum viral load in hepatitis C virus (HCV) infection has been used to evaluate the effects of anti-viral therapies. However, variability in HCV RNA levels in untreated patients with HCV infection has not yet been established. We therefore prospectively measured the biological fluctuations of HCV RNA in sera from untreated patients with chronic HCV infection. Sera were collected from seven patients at 8 am and 4 pm on the same day to assess the effect of diurnal variation, daily for 5 days in a further 10 patients, biweekly for 6 weeks in nine patients and monthly for 3 months in 11 patients. All patients had biopsy-proven chronic liver disease with elevated alanine aminotransferase (ALT) values and had not received anti-viral treatment. HCV RNA was measured blinded, in duplicate, using the quantitative branched (bDNA) amplification assay (Quantiplex HCV RNA, Chiron Co. Emeryville, CA) 36 of the 37 patients studied had measurable HCV RNA throughout the study. There was no significant correlation between HCV RNA levels and ALT values or histological activity. HCV RNA levels did not appear to vary significantly within any of the groups studied and there did not appear to be a change associated with diurnal variation. All individual patients demonstrated less than a threefold fluctuation in HCV RNA throughout the study period. Hence HCV RNA levels remain relatively stable in untreated individuals with chronic HCV infection. Changes of a magnitude of threefold (0.5 log) or greater in HCV RNA levels were not observed in untreated patients.

Current treatment of severely burned patients

OBJECTIVE

The authors provide an update on a multidisciplinary approach to the treatment of severely burned patients. A review of studies and clinical trials from the past to the present include fluid resuscitation, sepsis, immune function, hypermetabolism, early excision, wound healing, scar formation, and inhalation injury.

SUMMARY BACKGROUND DATA

Advances in treating initial burn shock, infection control, early wound closure, and modulation of the hypermetabolic response have decreased morbidity and mortality in the last two decades. Specialized burn care centers, using a multidisciplinary approach, not only successfully treat large burns and their complications, but provide the necessary rehabilitation and psychological support required for readjustment back into society.

CONCLUSIONS

Thermal injury results in a number of physiologic alterations that can be minimized by adequate fluid resuscitation to maintain tissue perfusion, early excision of burn wounds, and rapid wound coverage. These measures, in combination with antibiotic coverage and nutritional support in the form of early enteral tube feedings, will decrease the hypermetabolic response and the incidence of sepsis that can lead to hemodynamic instability and organ failure. Ongoing clinical trials using anabolic agents (e.g., recombinant human growth hormone) and pharmacologic agents that modulate inflammatory and endocrine mediators (e.g., ibuprofen and propranolol) show promise in the treatment of severe burn injuries.

MRI distortion and stereotactic neurosurgery using the Cosman-Roberts-Wells and Leksell frames

When not corrected, geometrically distorted magnetic resonance images may be unsuitable for stereotactic intracranial neurosurgical procedures where accuracy of target localization is critical. On a GE Signa 1.5-tesla system, we implemented an imaging protocol designed to improve the accuracy of the determination of target coordinates by means of multiple scans utilizing reversal of the frequency-encoded readout gradient. Using a Cosman-Roberts-Wells (CRW) frame and a phantom, geometric shifts of important image features were found to occur. In patients undergoing functional neurosurgical procedures with the CRW system, localization of the posterior commissure by corrected MR images was compared to that obtained by intraoperative ventriculography. Unexpectedly, severe distortions in MR images were revealed by the studies, with shifts of some fiducial markers of 10 mm from their estimated true position. Most of this distortion was attributable to the magnetic properties of the stereotactic frame, and could be eliminated by appropriate design and manufacture of the frame system. Images obtained with an MRI-compatible Leksell stereotactic frame were found to be relatively free of major geometric distortion. This study points out that properties of frame systems used for stereotactic neurosurgery may greatly influence the accuracy of frame-based stereotactic neurosurgery, and that the accuracy of these frame systems is testable.

Estrogen modulation of two subpopulations of β-endorphin neurons in ovariectomized guinea pigs distinguished by peripherally injected fluorogold

β-endorphin released by neurons in the arcuate nucleus affects the output of several neuroendocrine systems and estrogen levels modulate the production and secretion of β-endorphin. We used intraperitoneal injection of fluorogold to retrogradely label the cell bodies of neurons that project outside the blood-brain-barrier in conjunction with immunohistochemistry for β-endorphin to dual label the subpopulation of β-endorphin neurons that project to the median eminence or other sites of access to the peripheral circulation. We found that some identified β-endorphin neurons in the arcuate nucleus of ovariectomized guinea pigs sequestered fluorogold. Approximately 7% of β-endorphin-containing cells co-localized with fluorogold. The effect of estrogen on the number of identified β-endorphin cells was examined. A single estradiol benzoate injection to ovariectomized guinea pigs 24 h prior to sacrifice dramatically decreased the total number of β-endorphin cells identified in the rostral, medial and the caudal portions of the arcuate nucleus. Also, a significantly smaller percentage of fluorogold-filled cells was found to contain β-endorphin immunoreactivity in the estrogen-treated group. These data suggest that a subpopulation of β-endorphin neurons has access to the peripheral circulation and may alter the output of neurosecretory terminals at the level of the median eminence. Furthermore, estrogen affects this subpopulation and the general population of β-endorphin neurons in the arcuate nucleus in a similar manner.

Overview of lipoprotein metabolism: mechanisms involved and conveying this information to patients

The major classes of lipoprotein particles are chylomicrons, very-low-density lipoproteins, low-density lipoproteins, and high-density lipoproteins. Each of these particles has distinct characteristics, including a distinct apolipoprotein composition. The basic functions of these major apolipoproteins are briefly summarized for clinicians, and disorders of lipoprotein metabolism are discussed. For the effective management of lipid disorders, the therapy should be tailored to the specific defect. Compliance may be improved if the patient understands the nature of the particular lipid problem. To that end, we have developed an analogy in which the various classes of lipoprotein particles are equated to different trucking systems, and the liver is considered a warehouse for storage and distribution of fat. With use of this explanation, patients may understand the rationale for selection of various therapeutic strategies, and treatment of the hyper-lipoproteinemia is likely to be more successful.

Crude saponin extracted from Vietnamese ginseng and its major constituent majonoside-R2 attenuate the psychological stress- and foot-shock stress-induced antinociception in mice

Effects of Vietnamese ginseng (VG) crude saponin and majonoside-R2, a major saponin constituent, on the psychological stress- and foot shock stress-induced antinociception in the tail pinch test were examined in mice. VG crude saponin (6.2, 12.5, and 25 mg/kg, P.O.) attenuated psychological stress- but not foot shock stress-induced antinociceptive response, whereas majonoside-R2 (3, 6.2, and 12.5 mg/kg, P.O. and i.p.), as well as naloxone (2 mg/kg, i.p.), suppressed both psychological stress- and foot shock stress-induced antinociception. Pretreatment with the crude saponin (12.5 mg/kg, P.O.) or majonoside-R2 (6.2 mg/kg, P.O.) for 5 days followed by the treatment in combination with stress for next 5 days did not affect the development of adaptation to foot shock stress, but they significantly suppressed the antinociceptive action of the stress measured on the first, second, and third day during the stress exposure period. Majonoside-R2 (6.2 mg/kg, P.O.) but not the crude saponin (12.5 mg/kg, P.O.) significantly blocked the development of adaptation to psychological stress. These results suggest that VG crude saponin has the suppressing effect on psychological stress- and foot shock stress-induced antinociception and that majonoside-R2 is important for the action of the saponin.

Characterization of the MN gp120 HIV-1 vaccine: antigen binding to alum

PURPOSE

The characterization of recombinant MN gp120/alum vaccine requires the study of the gp120-alum interaction for the successful formulation of an alum-based HIV-1 vaccine.

METHODS

Several observations suggest that the gp120-alum interaction is weak, wherein buffer counterions such as phosphate, sulfate, bicarbonate may cause the desorption of gp120 from alum. Comparison of gp120 with other proteins using particle mobility measurements shows that the weak binding of gp120 to alum is not an anomaly. Serum and plasma also cause desorption of gp120 from alum with a half-life of only a few minutes, wherein this half-life may be faster than the in-vivo recruitment of antigen presenting cells to the site of immunization.

RESULTS

Immunization of guinea pigs, rabbits and baboons with gp120 formulated in alum or saline demonstrated that alum provides adjuvant activity for gp120, particularly after early immunizations, but the adjuvant effect is attenuated after several boosts.

CONCLUSIONS

These observations indicate that both the antigen and the adjuvant require optimization together.

Stimulation of muscle protein synthesis by long-term insulin infusion in severely burned patients

OBJECTIVE

To determine if long-term (7 days) infusion of insulin can ameliorate altered protein kinetics in skeletal muscle of severely burned patients and to investigate the hypothesis that changes in protein kinetics during insulin infusion are associated with an increased rate of transmembrane amino acid transport from plasma into the intracellular free amino acid pool.

SUMMARY BACKGROUND DATA

In critically ill patients, vigorous nutritional support alone may often fail to entirely curtail muscle catabolism; insulin stimulates muscle protein synthesis in normal volunteers.

METHODS

Nine patients with severe burns were studied once during enteral feeding alone (control period), and once after 7 days of high-dose insulin. The order of treatment with insulin was randomized. Data were derived from a model based on a primed-continuous infusion of L-[15N]phenylalanine, sampling of blood from the femoral artery and vein, and biopsies of the vastus lateralis muscle.

RESULTS

Net leg muscle protein balance was significantly (p < 0.05) negative during the control period. Exogenous insulin eliminated this negative balance by stimulating protein synthesis approximately 350% (p < 0.01). This was made possible in part by a sixfold increase in the inward transport of amino acids from blood (p < 0.01). There was also a significant increase in leg muscle protein breakdown. The new rates of synthesis, breakdown, and inward transport during insulin were in balance, such that there was no difference in the intracellular phenylalanine concentration from the control period. The fractional synthetic rate of protein in the wound was also stimulated by insulin by approximately 50%, but the response was variable and did not reach significance.

CONCLUSIONS

Exogenous insulin may be useful in promoting muscle protein synthesis in severely catabolic patients.

In vitro antimicrobial susceptibilities of strains of Yersinia pestis

The in vitro activities of 14 antimicrobial agents were determined for 78 strains of Yersinia pestis. The most active antibiotics were ceftriaxone and ciprofloxacin, followed by ofloxacin and ampicillin. The agents traditionally used for the treatment of plague (streptomycin, tetracycline, and chloramphenicol) were considerably less active. Azithromycin showed poor activity against all strains.

Gut mucosal ischemia during normothermic cardiopulmonary bypass results from blood flow redistribution and increased oxygen demand

Impaired gut mucosal perfusion has been reported during cardiopulmonary bypass. To better define the adequacy of gut blood flow and oxygenation during cardiopulmonary bypass, we measured overall gut blood flow and ileal mucosal flow and their relationship to mucosal pH, mesenteric oxygen delivery and oxygen consumption in immature pigs (n = 8). Normothermic, noncross-clamped, right atrium-to-aorta cardiopulmonary bypass was maintained at 100 ml/kg per minute for 120 minutes. Animals were instrumented with an ultrasonic Doppler flow probe on the superior mesenteric artery, a mucosal laser Doppler flow probe in the ileum, and pH tonometers in the stomach, ileum, and rectum. Radioactive microspheres were injected before and at 5, 60, and 120 minutes of cardiopulmonary bypass for tissue blood flow measurements. Overall gut blood flow significantly increased during cardiopulmonary bypass as evidenced by increases in superior mesenteric arterial flow to 134.1% +/- 8.0%, 137.1% +/- 7.5%, 130.3% +/- 11.2%, and 130.2% +/- 12.7% of baseline values at 30, 60, 90, and 120 minutes of bypass, respectively. Conversely, ileal mucosal blood flow significantly decreased to 53.6% +/- 6.4%, 49.5% +/- 6.8%, 58.9% +/- 11.6%, and 47.8% +/- 10.0% of baseline values, respectively. Blood flow measured with microspheres was significantly increased to proximal portions of the gut, duodenum and jejunum, during cardiopulmonary bypass, whereas blood flow to distal portions, ileum and colon, was unchanged. Gut mucosal pH decreased progressively during cardiopulmonary bypass and paralleled the decrease in ileal mucosal blood flow. Mesenteric oxygen delivery decreased significantly from 67.0 +/- 10.0 ml/min per square meter at baseline to 42.4 +/- 4.6, 44.9 +/- 3.5, 46.0 +/- 3.6, and 42.9 +/- 3.9 ml/min per square meter at 30, 60, 90, and 120 minutes of bypass. Despite the decrease in mesenteric oxygen delivery, mesenteric oxygen consumption increased progressively from 10.8 +/- 1.4 ml/min per square meter at baseline to 13.4 +/- 1.2, 15.9 +/- 1.2, 16.7 +/- 1.4, and 16.6 +/- 1.54 ml/min per square meter, respectively. We conclude that gut mucosal ischemia during normothermic cardiopulmonary bypass results from a combination of redistribution of blood flow away from mucosa and an increased oxygen demand.

Synergy between signal transduction pathways is obligatory for expression of c-fos in B and T cell lines: implication for c-fos control via surface immunoglobulin and T cell antigen receptors

Expression of the protooncogene c-fos is controlled by three main regulatory pathways involving kinase C, cAMP, and calcium. Kinase C mediates its effects via phosphorylation of serum response factor (SRF) which interacts with the serum response element (SRE); cAMP and calcium mediate their effects via phosphorylation of CREB (cAMP regulatory element binding protein) presumably by activation of a protein kinase A or calmodulin-regulated kinase. We have examined the function of these elements in Burkitt's lymphoma cells (Ramos and Daudi) as well as a T lymphocytic cell line (Jurkat). We have found that stimulation of any one of these pathways alone has little or no effect on c-fos induction. However, kinase C activation (PMA stimulation) combined with either cAMP (forskolin plus MIX) or calcium stimulation (ionophore) leads to greatly enhanced c-fos induction. By contrast, cAMP in the presence of calcium shows no synergy in c-fos induction. Okadaic acid augments PMA- as well as calcium-mediated activation of c-fos, and has little or no effect when combined with cAMP. The main difference between Ramos (B cells) and Jurkat (T cells) in the regulation of c-fos is that cAMP plus calcium is strongly synergistic in Jurkat and is without effect in Ramos. Analysis of AP-1 activity using gel mobility shift assays confirms that the requirements for synergy in c-fos mRNA induction are paralleled by requirements for synergy in induction of AP-1 activity. Signaling in B cells due to anti-Ig stimulation involves both kinase C activation and release of intracellular calcium, and results in c-fos mRNA induction. Our results indicate that synergy between the kinase C activation and calcium is needed for efficient c-fos induction since neither of these two alone induces c-fos well. That synergy of signaling pathways is relevant for the anti-Ig induction of c-fos is supported by the fact that cAMP-inducing agents and okadaic acid further enhance anti-Ig induction of c-fos. These results suggest that cell-specific patterns of synergy are an essential feature for c-fos induction and may be relevant for c-fos control through B and T cell antigen receptors.

Production of isoleucine by overexpression of ilvA in a Corynebacterium lactofermentum threonine producer

Overproduction of isoleucine, an essential amino acid, was achieved by amplification of the gene encoding threonine dehydratase, the first enzyme in the threonine to isoleucine pathway, in a Corynebacterium lactofermentum threonine producer. Threonine overproduction was previously achieved with C. lactofermentum ATCC 21799, a lysine-hyperproducing strain, by introduction of plasmid pGC42 containing the Corynebacterium homdr and thrB genes (encoding homoserine dehydrogenase and homoserine kinase respectively) under separate promoters. The pGC42 derivative, pGC77, also contains ilvA, which encodes threonine dehydratase. In a shake-flask fermentation, strain 21799(pGC77) produced 15 g/l isoleucine, along with small amounts of lysine and glycine. A molar carbon balance indicates that most of the carbon previously converted to threonine, lysine, glycine and isolecine was incorporated into isoleucine by the new strain. Thus, in our system, simple overexpression of wild-type ilvA sufficed to overcome the effects of feedback inhibition of threonine dehydratase by the end-product, isoleucine.

Complications of skull base surgery

The increasing number of patients undergoing resection of complex skull base lesions with good outcome is indicative of the interest and expertise in treating tumors of the skull base. Advances in surgical techniques and improved knowledge of the microanatomy have contributed to the ability to manage these tumors aggressively. These procedures are not without morbidity, such as neurologic deficits, infection, and hemorrhage. These complications are expected and, with appropriate and timely management, can be minimized.

Effects of manganese superoxide dismutase on lung fluid balance after smoke inhalation

There is evidence of increased oxygen free radical activity after smoke inhalation with and without concomitant burn injury. We determined the effects of manganese superoxide dismutase (Mn SOD) on lung fluid balance as measured by lung microvascular permeability coefficient (sigma), filtration coefficient (Kf), and lymph flow. Merino breed ewes (n = 6/group) were surgically prepared. The SOD group (SOD) received Mn SOD (9,000 U/kg) as an intravenous bolus and was insufflated with smoke. The control group (CON) received saline and smoke. sigma and Kf were determined 24 h before and 24 h after smoke injury. Lymph flow, arterial O2-to-inspired O2 fraction ratio, systemic hemodynamics, and pulmonary arterial and capillary pressures were measured. The sigma was significantly (P < 0.05) higher after smoke insufflation in SOD compared with CON (0.71 +/- 0.03 vs. 0.53 +/- 0.05). Kf was significantly lower after smoke insufflation in SOD compared with CON (0.038 +/- 0.010 vs. 0.061 +/- 0.010). Lymph flows were significantly lower during the 24 h after smoke insufflation in SOD compared with CON (33 +/- 7 vs. 55 +/- 8 ml/h at 24 h). Arterial O2-to-inspired O2 fraction ratio was significantly improved at 6 and 12 h after smoke insufflation in SOD compared with CON at the same time points. Mn SOD meliorates the lung microvascular permeability changes associated with smoke inhalation injury.

Characterization of growth hormone enhanced donor site healing in patients with large cutaneous burns

BACKGROUND

Human growth hormone is an anabolic agent that attenuates injury-induced catabolism and stimulates protein synthesis. Recombinant human growth hormone (rhGH) administered therapeutically to patients with massive burns has been shown to increase the rate of skin graft donor site healing. It has been postulated that growth hormone affects wound healing and tissue repair by stimulating the production of insulin-like growth factor-1 (IGF-1) by the liver to increase circulating IGF-1 concentrations. The mechanism by which it improves wound healing, however, remains in question. The authors hypothesize that rhGH up-regulates IGF-1 receptors and IGF-1 levels both systemically and locally in the wound site to stimulate cell mitosis and increase synthesis of laminin, collagen types IV and VII, and cytokeratin. This hypothesis was tested in nine patients with burns covering > 40% of total body surface area.

OBJECTIVE

The authors assessed the efficacy of rhGH in promoting several major building materials in the donor site of patients with massive burns.

METHODS

Ten massively burned patients with full-thickness burns covering more than 40% of total body surface area were participants in a placebo-controlled prospective study to determine the efficacy of 0.2 mg/kg/day rhGH on donor site wound healing and to identify some of the major components involved in wound healing and its integrity.

RESULTS

Donor sites in burn patients receiving rhGH showed an increased coverage by the basal lamina of 26% for placebo to 68% coverage of the dermal-epidermal junction. Insulin-like growth factor-1 receptors and laminin, types IV and VII collagen, and cytokeratin-14 all increased significantly. Healing times of the donor sites were significantly decreased compared with patients receiving placebo.

CONCLUSION

Results indicate that growth hormone or its secondary mediators may directly stimulate the cells of the epidermis and dermis during wound healing to produce the structural proteins and other components needed to rebuild the junctional structures.

Hypertonic acetate dextran achieves high-flow-low-pressure resuscitation of hemorrhagic shock

OBJECTIVE

For resuscitation of hemorrhagic hypovolemia, we compared the effectiveness of (1) isotonic lactated Ringer's solution (LRS), (2) 2400 mOsm of 7.5% NaCl:6% dextran 70 (HSD), and (3) 2400 mOsm of 7.9% sodium acetate:1.9% NaCl:6% dextran 70 (HAD).

DESIGN

In six randomized, blinded experiments for each solution, conscious instrumented adult sheep were hemorrhaged by removing approximately 1.8 L (42 +/- 3 mL/kg) of blood, while maintaining the mean arterial pressure (MAP) at 50 mm Hg for 2 hours.

METHODS

Test solutions were infused as needed to restore the cardiac index to baseline.

RESULTS

Volume requirements with HAD (236 +/- 29 mL) and HSD (244 +/- 39 mL) were significantly less (p < 0.05) than LRS (3463 +/- 234 mL). Mean arterial pressure was normalized with HSD and LRS, but not with HAD, which resulted in MAPs of 20 to 25 mm Hg less than baseline resulting from a reduced peripheral resistance. Oxygen delivery, however, was significantly higher with HAD during the resuscitation period. Acid-base balance (pH) and oxygen consumption were normalized within 5 minutes of infusion only with HAD.

CONCLUSIONS

Small-volume infusion with HAD resulting in "high-flow-low-pressure" resuscitation may offer unique hemodynamic and metabolic advantages for the initial treatment of hemorrhage from trauma.

Short course of ofloxacin for treatment of multidrug-resistant typhoid

In recent years, multiresistant strains of Salmonella typhi have emerged in many tropical countries. These strains remain highly sensitive to the fluoroquinolone antibiotics, although use of these drugs by children is considered contraindicated because of their reported toxicity in the cartilage of experimental animals. In a paired, open, randomized study during an epidemic of multidrug-resistant typhoid in southern Vietnam, two short-course ofloxacin regimens (15 mg/kg daily for 3 days and 10 mg/kg daily for 5 days) were compared for the treatment of uncomplicated typhoid fever. Of 438 patients enrolled (of whom 286 were < or = 14 years old), 228 had blood cultures positive for Salmonella species (S. typhi, 207; S. paratyphi A, 19; and S. choleraesuis, 2). There was one treatment failure in a patient who took only one dose of ofloxacin. Otherwise, both regimens were completely effective; there were no proven carriers, and there was no evidence of toxicity, particularly in children. A 3-day course of ofloxacin proved to be safe and highly effective in the treatment of uncomplicated, multidrug-resistant typhoid fever.

Dimethyl sulfoxide suppresses apoptosis in Burkitt's lymphoma cells

Previous reports have suggested that dimethyl sulfoxide (DMSO) may be a useful reversible G1 arresting agent for synchronizing Raji Burkitt's lymphoma cells (K. Takase et al. (1992) Cell Growth Differ. 3, 515-521; M. Sawai et al. (1990) Exp. Cell Res. 187, 4-10). We have therefore critically evaluated several aspects of DMSO's effects using Daudi and Ramos Burkitt's lymphoma (BL) cells. In BL cells starved in the presence or absence of DMSO for 4 to 6 days (approximately four to six doubling times), the following observations were noted: (A) Both Daudi and Ramos cells show increased cell synchrony accompanied by apoptosis when starved in RPMI 1640 supplemented with 10% fetal calf serum (FCS). Inclusion of 1.5% DMSO causes a diminution in apoptosis with minimal effects on synchrony. (B) Lowering the FCS concentration to 5% induces apoptosis. DMSO-mediated protection from apoptosis is observed in Daudi but not in Ramos. (C) When human serum (10%) is used instead of FCS, Daudi cells show no apoptosis and DMSO is without effect on cell cycle distribution. By contrast, Ramos cells show significant apoptosis, which is prevented by the inclusion of DMSO. (D) When starved in a chemically defined medium (AIM-V), both Daudi and Ramos cells show significant apoptosis. DMSO protects Ramos from apoptosis under these conditions. (E) Upon removal of DMSO, both Daudi and Ramos cells reenter the cell cycle but with significant apoptosis. (F) The protective effect of DMSO from apoptosis is observed in a narrow range of concentration between 1 and 2%. At higher concentration, DMSO itself induces apoptosis. These results suggest that DMSO itself prevents apoptosis, an effect which may present as an apparent effect on cell synchrony.

The role of lipoprotein A-I and lipoprotein A-I/A-II in predicting coronary artery disease

The aim of this study was to examine the role of HDL subparticles with apolipoprotein (apo) A-I alone (LpA-I) and with apoA-I and apoA-II (LpA-I/A-II) in predicting coronary artery disease. Concentrations of these HDL subparticles were compared in 184 subjects with angiographically confirmed significant coronary artery disease (> 50% stenosis of at least one vessel) and 191 age- and sex-matched control subjects without clinical coronary artery disease. LpA-I and LpA-I/A-II were measured with magnetic beads coated with anti-apoA-II antibodies to separate particles containing apoA-II from plasma. Total plasma cholesterol and triglyceride levels were similar in both groups. Although subjects with coronary artery disease had lower HDL cholesterol, plasma apoA-I, LpA-I, and LpA-I/A-II than age- and sex-matched control subjects without coronary artery disease, plasma apoA-I was the best predictor of coronary artery disease. In conclusion, LpA-I and LpA-I/A-II are lower in subjects with coronary artery disease but do not add to plasma apoA-I in predicting the presence of coronary artery disease.

Selectively 13C-enriched DNA: dynamics of the C1'-H1' vector in d(CGCAAATTTGCG)2

In order to examine the internal dynamic processes of the dodecamer d(CGCAAATTTGCG)2, the 13C-enriched oligonucleotide has been synthesized. The three central thymines were selectively 13C-labeled at the C1' position and their spin-lattice relaxation parameters R(CZ), R(CX,Y), R(HZ-->CZ), R(2HZCZ), R(2HZCX,Y) and R(HZC) were measured. Density functions were computed for two models of internal motions. Comparisons of the experimental data were made with spin-lattice relaxation rates rather than with the density functions, whose values were altered by accumulation of the uncertainties of each relaxation rate measurement. The spin-lattice relaxation rates were computed with respect to the motions of the sugar around the C1'-N1 bond. A two-state jump model between the anti- and syn-conformations with P(anti)/P(syn) = 91/9 or a restricted rotation model with delta chi = 28 degrees and an internal diffusion coefficient of 30 x 10(7) s-1 gave a good fit with the experimental data. Twist, tilt or roll base motions have little effect on 13C1' NMR relaxation. Simulation of spin-relaxation rates with the data obtained at several temperatures between 7 and 32 degrees C, where the dodecamer is double stranded, shows that the internal motion amplitude is independent of the temperature within this range, as expected for internal motion. Using the strong correlation which exists in a B-DNA structure between the chi and delta angle, we suggest that the change in the glycosidic angle value should be indicative of a sugar puckering between the C1'-exo and C2'-endo conformations.

Cephalosporin vs penicillin

The correlation between late infection of an orthopedic prosthesis and a dental bacteremia remains controversial. Transient bacteremia does occur after dental treatment, usually involving streptococcal bacteria, but many orthopedic surgeons choose an anti-staphylococcal agent as their prophylactic antibiotic of choice. This article reports the results of a recent survey designed to determine, from orthopedic surgeons, antibiotic premedication coverage and, specifically, the rationale for a chosen regimen for patients having dental surgery. The responses showed no common agreement for the choice of a specific antibiotic and little rationale regarding the need for prophylaxis.

Effect of inducible thrB expression on amino acid production in Corynebacterium lactofermentum ATCC 21799

Amplification of the operon homdr-thrB encoding a feedback-insensitive homoserine dehydrogenase and a wild-type homoserine kinase in a Corynebacterium lactofermentum lysine-producing strain resulted in both homoserine and threonine accumulation, with some residual lysine production. A plasmid enabling separate transcriptional control of each gene was constructed to determine the effect of various enzyme activity ratios on metabolite accumulation. By increasing the activity of homoserine kinase relative to homoserine dehydrogenase activity, homoserine accumulation in the medium was essentially eliminated and the final threonine titer was increased by about 120%. Furthermore, a fortuitous result of the cloning strategy was an unexplained increase in homoserine dehydrogenase activity. This resulted in a further decrease in lysine production along with a concomitant increase in threonine accumulation.