Inhibition of growth of methane-producing bacteria of the ruminant forestomach by hydroxymethylglutaryl-SCoA reductase inhibitors.

Two hydroxymethylglutaryl-SCoA (HMG-CoA) reductase inhibitors, mevastatin and lovastatin, inhibited the in vitro growth and production of CH4 of strains of Methanobrevibacter isolated from the rumen. Mevastatin or lovastatin did not inhibit growth of species of rumen bacteria that are essential for fermenting cellulose, starch and other plant polysaccharides to acetate, propionate, and butyrate. Approximately 4 nmol of lovastatin per milliliter resulted in 50% growth inhibition of Methanobrevibacter strain ZA10 and concentrations > or =10 nmol per milliliter completely inhibited growth and CH4 formation. Results of in vitro growth studies suggest that supplementation of ruminant feeds with HMG-CoA inhibitors could decrease ruminant methane production and increase the efficiency of feed utilization by domestic ruminants.

Anaerobic bioconversion of cellulose by Ruminococcus albus, Methanobrevibacter smithii, and Methanosarcina barkeri.

A system is described that combines the fermentation of cellulose to acetate, CH4, and CO2 by Ruminococcus albus and Methanobrevibacter smithii with the fermentation of acetate to CH4 and CO2 by Methanosarcina barkeri to convert cellulose to CH4 and CO2. A cellulose-containing medium was pumped into a co-culture of the cellulolytic R. albus and the H2-using methanogen, Mb. smithii. The effluent was fed into a holding reservoir, adjusted to pH 4.5, and then pumped into a culture of Ms. barkeri maintained at constant volume by pumping out culture contents. Fermentation of 1% cellulose to CH4 and CO2 was accomplished during 132 days of operation with retention times (RTs) of the Ms. barkeri culture of 7.5-3.8 days. Rates of acetate utilization were 9.5-17.3 mmol l(-1) day(-1) and increased with decreasing RT. The Ks for acetate utilization was 6-8 mM. The two-stage system can be used as a model system for studying biological and physical parameters that influence the bioconversion process. Our results suggest that manipulating the different phases of cellulose fermentation separately can effectively balance the pH and ionic requirements of the acid-producing phase with the acid-using phase of the overall fermentation.

Low-dose daily subcutaneous interleukin-2 in combination with highly active antiretroviral therapy in HIV+ patients: a randomized controlled trial.

PURPOSE: Previous studies with intermittent interleukin-2 (IL-2) therapy using intermediate and high levels of IL-2 have demonstrated significant increases in the CD4 + T cell count in HIV-infected patients. Intermittent regimens are amenable to outpatient use, but severe adverse events are frequently experienced with intermediate- and high-dose levels of IL-2. Therefore in this study, the effect of daily, subcutaneous low-dose IL-2 therapy on safety and immunological endpoints was investigated to determine whether immunological benefit could be achieved without toxicity in HIV-infected patients also receiving highly active antiretroviral therapy (HAART). METHOD: A total of 115 patients were enrolled in the trial. Fifty-six asymptomatic HIV-infected patients who had CD4 + T cell counts less than 300 cells/microL at screening and a stable HIV viral load received low-dose IL-2 (1.2 million IU [MIU]/m 2 beginning dose) once daily in conjunction with HAART (IL-2 group). Fifty-nine patients received HAART alone (control group). RESULTS: A dramatic effect of IL-2 on the natural killer (NK) cell population was observed with mean increases of 156 cells/microL in the IL-2 group compared to 19.93 cells/microL in the control group (p <.001). Additionally, IL-2-treated patients experienced a statistically significant increase in the mean percentage of CD4 + T cells (3.52% increase) when compared to control patients (1.33% increase) (p <.001). The expanded CD4 + T cell population was primarily of the naive phenotype, with mean increases of 4.53% for the IL-2 group and 0.31% for the control group (p <.001 for between-group difference). In addition, a higher proportion of IL-2-treated patients (67%) compared to control patients (33%) achieved increases of greater than 50% in the CD4+ T cell count (p =.08). Adverse events of grade 3 or grade 4 toxicity were infrequent in the current study and were substantially lower by comparison to those in studies of intermittent dose IL-2 therapy. Also, negligible changes in the HIV viral load from baseline to final measurement were observed in both groups. A trend toward a reduced number of modifications of antiretroviral therapy was apparent in the IL-2 group when compared to control patients. CONCLUSION: Daily, low-dose subcutaneous IL-2 therapy in conjunction with HAART is safe and well tolerated and is effective in expanding lymphocyte cell types including NK cells and naive T cells in individuals who have <300 CD4+ T cells.

Changes of fermentation pathways of fecal microbial communities associated with a drug treatment that increases dietary starch in the human colon.

Acarbose inhibits starch digestion in the human small intestine. This increases the amount of starch available for microbial fermentation to acetate, propionate, and butyrate in the colon. Relatively large amounts of butyrate are produced from starch by colonic microbes. Colonic epithelial cells use butyrate as an energy source, and butyrate causes the differentiation of colon cancer cells. In this study we investigated whether colonic fermentation pathways changed during treatment with acarbose. We examined fermentations by fecal suspensions obtained from subjects who participated in an acarbose-placebo crossover trial. After incubation with [1-13C]glucose and 12CO2 or with unlabeled glucose and 13CO2, the distribution of 13C in product C atoms was determined by nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry. Regardless of the treatment, acetate, propionate, and butyrate were produced from pyruvate formed by the Embden-Meyerhof-Parnas pathway. Considerable amounts of acetate were also formed by the reduction of CO2. Butyrate formation from glucose increased and propionate formation decreased with acarbose treatment. Concomitantly, the amounts of CO2 reduced to acetate were 30% of the total acetate in untreated subjects and 17% of the total acetate in the treated subjects. The acetate, propionate, and butyrate concentrations were 57, 20, and 23% of the total final concentrations, respectively, for the untreated subjects and 57, 13, and 30% of the total final concentrations, respectively, for the treated subjects.

Decompression sickness risk in rats by microbial removal of dissolved gas.

We present a method for reducing the risk of decompression sickness (DCS) in rats exposed to high pressures of H2. Suspensions of the human colonic microbe Methanobrevibacter smithii were introduced via a colonic cannula into the large intestines of the rats. While the rats breathed H2 in a hyperbaric chamber, the microbe metabolized some of the H2 diffusing into the intestine, converting H2 and CO2 to methane and water. Rate of release of methane from the rats, which was monitored by gas chromatography, varied with chamber H2 pressure. This rate was higher during decompression than during compression, suggesting that during decompression the microbe was metabolizing H2 stored in the rats' tissues. Rats treated with M. smithii had a 25% (5 of 20) incidence of DCS, which was significantly lower (P < 0.01) than the 56% (28 of 50) incidence of untreated controls, brought on by a standardized compression and decompression sequence. Thus using a microbe in the intestine to remove an estimated 5% of the body burden of H2 reduced DCS risk by more than one-half. This method of biochemical decompression may potentially facilitate human diving.

Digoxin visual toxicity with therapeutic blood levels of digoxin.

PURPOSE: To report two cases of digoxin-related visual disturbances associated with therapeutic blood levels of digoxin. METHODS: Case reports. One patient reported shimmering lights in the field of vision of both eyes; the second patient had a corrected visual acuity of BE, 20/40 and generalized visual field depression in both eyes. Both patients experienced these symptoms while receiving digoxin. RESULTS: Both patients had digoxin blood levels in the therapeutic range (1.7 and 1.0 ng/ml, respectively). Therapeutic levels are 0.5 to 2.0 ng/ml. After discontinuing digoxin, the first patient noted that the shimmering light symptoms resolved, and the second patient had improved visual acuity and visual fields. CONCLUSIONS: Digoxin-related visual toxicity may be associated with therapeutic blood levels of digoxin. Recognition of this entity may avoid unnecessary testing and frustration.

Changes in production of ethanol, acids and H2 from glucose by the fecal flora of a 16- to 158-d-old breast-fed infant.

Microbes in the adult human colon ferment dietary substrates chiefly to acetic, propionic and butyric acids and CO2, H2 and CH4. How this fermentation evolves after microbial colonization of the neonate is unknown. We examined the fermentation of glucose by fecal suspensions of a breast-fed infant from d 16 to 158 and found that the fermentation changed with age. Acetate, ethanol, succinate, lactate, formate and H2 were formed up to 117 d of age. Production of succinate, lactate, formate and H2 ceased after 117 d and acetate production increased. Butyrate and propionate were minor products up to 117 d. Afterwards, there was a slight increase in propionate production with no change in butyrate formation. Acetate was always the major product of glucose fermentation by the fecal suspensions. Approximately the same amounts of ethanol were formed throughout the study period. The fermentations were similar to fermentations of Escherichia coli and streptococci through 117 d. Nuclear magnetic resonance (NMR) analysis of the acetate formed from 1-13C- and 3-13C-glucose showed that the dominant fermentation pathway used by the colonic microbes switched from the Embden-Meyerhof-Parnas pathway at 16 d of age to the Bifidobacterium pathway at 158 d of age. An increase in the contribution of the Bifidobacterium fermentation to the overall colonic fermentation after 117 d would account for the increase in the formation of acetate from glucose. Chemical and NMR analyses of products of fecal fermentations from two other breast-fed infants <1 mo old were similar to those of the infant examined between 16 and 158 d.

NMR detection of 13CH313COOH from 3-13C-glucose: a signature for Bifidobacterium fermentation in the intestinal tract.

The gastrointestinal tracts of breast-fed infants are colonized more easily with bifidobacteria than are those of formula-fed infants. Colonization is thought to reduce infant diarrhea. Amendments to formulas that improve colonization by bifidobacteria are being actively investigated. Colonization studies almost invariably require measurements of the concentration of the bifidobacteria in feces to assess their importance in the colon. We investigated the use of nuclear magnetic resonance (NMR) analysis of products of fermentations of 1- and 3-13C-glucose to evaluate the importance of bifidobacteria in the colonic ecosystem. Bifidobacteria use a unique pathway of hexose catabolism to produce primarily acetate and lactate. The fermentation yields 3 mol of acetate from 2 mol of glucose. Two of the acetates are formed from C1 and C2 of glucose and the third is formed entirely from C3 of glucose. We first employed high resolution NMR to verify the pathway used by a pure culture of Bifidobacterium bifidum. The major products of fermentation of 1- and 3-13C-glucose were acetate and lactate. Most of the 13C from 3-13C-glucose was in 13CH313COOH with equal enrichment in the methyl and carboxyl groups. The 13C-acetate from 1-13C-glucose was almost entirely enriched in the methyl of acetate and no 13CH313COOH was produced. NMR analysis of glucose fermentation by the colonic flora of a 158-d-old strictly breast-fed infant showed production of 13CH313COOH from 3-13C-glucose. The amount of 13CH313COOH formed established that the Bifidobacterium pathway was the major pathway used for glucose fermentation by this infant's colonic microbes.

Toxicity management in patients receiving low-dose aldesleukin therapy.

OBJECTIVE: To review the pathophysiology and subsequent treatment options for low-dose aldesleukin-induced toxicity when administered via intravenous bolus infusion, continuous intravenous infusion, or subcutaneous injection. BACKGROUND: The adverse events associated with high-dose aldesleukin therapy (600,000 IU per kg i.v. every 8 h for a maximum of 14 doses) are well documented in the literature; however, the adverse event profile of lower doses and alternative administration routes are less well described. An understanding of the adverse event profile associated with these alternative regimens can enhance management of toxicity. DATA SOURCES: English-language clinical studies, abstracts, and review articles pertaining to low-dose intravenous, continuous intravenous infusion, or subcutaneous injection of aldesleukin, as well as aldesleukin-induced adverse events. STUDY SELECTION AND DATA EXTRACTION: Relevant studies were selected that assist with understanding the pathophysiology, clinical management, diagnosis, and management of aldesleukin-induced adverse events. CONCLUSIONS: Aldesleukin therapy initiates a cytokine-mediated proinflammatory process resulting in a toxicity profile that is different from traditional nonbiologic chemotherapeutic agents. The frequency and severity of adverse events associated with aldesleukin administration are dependent upon dose, route, and administration schedule. In addition, most adverse reactions are self-limiting. Alleviation of aldesleukin-induced adverse effects can usually be achieved on an outpatient basis with agents such as antiemetics, antipyretics, and topical creams or lotions, as well as nonmedication interventions. Aggressive and proactive management of aldesleukin associated toxicities can help facilitate completion of therapy.

Neuro-ophthalmologic manifestations of adenoid cystic carcinoma.

Intracranial adenoid cystic carcinoma is uncommon. We report two unusual cases of intracranial adenoid cystic carcinoma. The first patient presented with a steroid-responsive optic neuropathy from an orbital mass that simulated orbital pseudotumor, and subsequently developed intracranial involvement, presumably by contiguous perineural spread. The second patient presented with proptosis of the left eye, right facial weakness and numbness, and an intracranial mass, presumably from hematogenous metastatic spread.

In vitro activities of ciprofloxacin and rifampin alone and in combination against growing and nongrowing strains of methicillin-susceptible and methicillin-resistant Staphylococcus aureus.

We characterized the effects of ciprofloxacin and rifampin alone and in combination on Staphylococcus aureus in vitro. The effects of drug combinations (e.g., indifferent, antagonistic, or additive interactions) on growth inhibition were compared by disk approximation studies and by determining the fractional inhibitory concentrations. Bactericidal effects in log-phase bacteria and in nongrowing isolates were characterized by time-kill methods. The effect of drug combinations was dependent upon whether or not cells were growing and whether killing or growth inhibition was the endpoint used to measure drug interaction. Despite bactericidal antagonism in time-kill experiments, our in vitro studies suggest several possible explanations for the observed benefits in patients treated with a combination of ciprofloxacin and rifampin for deep-seated staphylococcal infections. Notably, when growth inhibition rather than killing was used to characterize drug interaction, indifference rather than antagonism was observed. An additive bactericidal effect was observed in nongrowing bacteria suspended in phosphate-buffered saline. While rifampin antagonized the bactericidal effects of ciprofloxacin, ciprofloxacin did not antagonize the bactericidal effects of rifampin. Each antimicrobial prevented the emergence of subpopulations that were resistant to the other.

Acarbose enhances human colonic butyrate production.

Earlier studies suggest that butyrate has colonic differentiating and nutritional effects and that acarbose increases butyrate production. To determine the effects of acarbose on colonic fermentation, subjects were given 50-200 mg acarbose or placebo (cornstarch), three times per day, with meals in a double-blind crossover study. Fecal concentrations of starch and starch-fermenting bacteria were measured and fecal fermentation products determined after incubation of fecal suspensions with and without added substrate for 6 and 24 h. Substrate additions were cornstarch, cornstarch plus acarbose and potato starch. Dietary starch consumption was similar during acarbose and placebo treatment periods, but fecal starch concentrations were found to be significantly greater with acarbose treatment. Ratios of starch-fermenting to total anaerobic bacteria were also significantly greater with acarbose treatment. Butyrate in feces, measured either as concentration or as percentage of total short-chain fatty acids, was significantly greater with acarbose treatment than with placebo treatment. Butyrate ranged from 22.3 to 27.5 mol/100 mol for the 50-200 mg, three times per day doses of acarbose compared with 18.3-19.3 mol/100 mol for the comparable placebo periods. The propionate in fecal total short-chain fatty acids was significantly less with acarbose treatment (10.7-12.1 mol/100 mol) than with placebo treatment (13.7-14.2 mol/100 mol). Butyrate production was significantly greater in fermentations in samples collected during acarbose treatment, whereas production of acetate and propionate was significantly less. Fermentation decreased when acarbose was added directly to cornstarch fermentations. Acarbose effectively augmented colonic butyrate production by several mechanisms; it reduced starch absorption, expanded concentrations of starch-fermenting and butyrate-producing bacteria and inhibited starch use by acetate- and propionate-producing bacteria.

Therapy of acute myelogenous leukemia: understanding the question, understanding the answer.

The best therapy for people with acute myelogenous leukemia (AML) in first remission is controversial. Options include postremission chemotherapy, a bone marrow transplant (HLA-identical sibling or autotransplant) or chemotherapy followed by a transplant at relapse. Four large cooperative group trials address this issue. In this review design and implementation of these trials is considered. Whether data from these trials will answer the questions of the best therapy for AML in first remission, is focused upon.

Pathways of acetate, propionate, and butyrate formation by the human fecal microbial flora.

The pathways of short-chain fatty acid (SCFA; acetate, propionate, and butyrate) formation from glucose were determined for the human fecal microbial communities of two subjects. The pathways were identified by radioisotope analysis of the SCFA and CO2 obtained after incubation of fecal suspensions with glucose under 20% CO2 with [1-14C]glucose, [3,4-14C]glucose, or 14CO2. Acetate was chemically degraded to learn the labeling of the methyl and carboxyl carbons. The labeling of CO2 and acetate showed that the major route of glucose catabolism was the Embden-Meyerhof-Parnas pathway, with production of CO2 from pyruvate carboxyl carbon. Labeling of the methyl and carboxyl carbons of acetate by 14CO2 or [3,4-14C]glucose proved that acetate was formed from CO2 by the Wood-Ljungdahl pathway. CO2 reduction accounted for about one-third of the acetate formed by suspensions from subject 1 and about one-fourth of the acetate formed by suspensions from subject 2. Propionate was formed by a CO2 fixation pathway, and butyrate was formed by classical routes of acetyl-S coenzyme A condensation. The amount of CO2 formed from [1-14C] glucose and acetate labeling patterns obtained with the other 14C precursors indicated that the Entner-Doudoroff, transketolase-transaldolase, and heterolactic pathways were not significant. Fermentation of cabbage cellulose by subject 1 followed the same pathways as were used for glucose. The results with suspensions from subject 2 suggested that some radioactive acetate was formed from the C-3 of glucose by the Bifidobacterium pathway.

Oculopalatal myoclonus after the one-and-a-half syndrome with facial nerve palsy.

PURPOSE: The one-and-a-half syndrome is an eye movement disorder characterized by a unilateral gaze palsy and an ipsilateral internuclear ophthalmoplegia. The authors describe a previously unrecognized association between the one-and-a-half syndrome and oculopalatal myoclonus (OPM). METHODS: Five clinical cases are presented, with pertinent physical findings and radiologic studies. RESULTS: A previously unrecognized association of the one-and-a-half syndrome with subsequent development of OPM appears to exist. Involvement of the facial nerve in patients with the one-and-a-half syndrome may be a predictor of the subsequent development of OPM. CONCLUSION: Patients with the one-and-a-half syndrome and facial nerve palsy should be followed closely for possible future development of OPM.

Acute graft-versus-host disease in a recipient of a twin blood cell transplant.

There are reports of acute graft-versus-host disease (GVHD) after autologous and twin bone marrow transplants but they are controversial because of the difficulty of accurate diagnosis. We report a subject with Philadelphia chromosome-positive CML who received two syngeneic transplants of blood cells. In the first transplant of 2.6 x 10(8) mononuclear cells/kg, no pretransplant conditioning was given; in the second transplant of 4.9 x 10(8) mononuclear cells/kg, pretransplant conditioning therapy consisted of chemotherapy and TBI. Although no symptoms were seen after the first transplant, the second was followed by fever, diarrhea, rash and liver function test abnormalities coincident with engraftment. Symptoms resolved spontaneously. The patient was not on any medication and had not received any transfusions. Our observations suggest either that acute GVHD in a twin transplant is a direct consequence of conditioning or that pretransplant conditioning is a prerequisite for developing features resembling acute GVHD.

Bioconversion of Cellulose to Acetate with Pure Cultures of Ruminococcus albus and a Hydrogen-Using Acetogen.

Bioconversion of cellulose to acetate was accomplished with cocultures of two organisms. One was the cellulolytic species Ruminococcus albus. It ferments crystalline cellulose (Avicel) to acetate, ethanol, CO(inf2), and H(inf2). The other organism (HA) obtains energy for growth by using H(inf2) to reduce CO(inf2) to acetate. HA is a gram-negative coccobacillus that was isolated from horse feces. Coculture of R. albus with HA in batch or continuous culture alters the fermentation products formed from crystalline cellulose by the ruminococcus via interspecies H(inf2) transfer. The major product of the fermentation by R. albus and HA coculture is acetate. High concentrations of acetate (333 mM) were obtained when batch cocultures grown on 5% cellulose were neutralized with Ca(OH)(inf2). Continuous cocultures grown at retention times of 2 and 3.1 days produced 109 and 102 mM acetate, respectively, when fed 1% cellulose with utilization of 84% of the substrate.

Digitalis-induced visual disturbances with therapeutic serum digitalis concentrations.

OBJECTIVE: To assess the role of digitalis in the development of visual symptoms severe enough to warrant ophthalmologic consultation in patients who received digitalis and who had no other clinical or laboratory evidence of digitalis toxicity. DESIGN: Clinical case study. SETTING: Neuro-ophthalmology referral practice. PATIENTS: Six elderly patients (aged 66 to 85 years) who received digitalis were referred to ophthalmologists for evaluation of photopsia (five patients) or decreased visual acuity (one patient). No patient had chromatopsia or nonvisual clinical manifestations of digitalis intoxication at the time of examination. MEASUREMENTS: All patients had serum digitalis concentrations within or below the therapeutic range. In most patients, the electroretinographic cone b-wave implicit time was longer than normal. RESULTS: Discontinuation of digitalis therapy, which was possible in five patients, was followed by resolution of visual symptoms and by shortening of the b-wave implicit time. Characteristic features of digitalis-induced photopsia were its dependence on illumination and its tendency to be localized in peripheral visual fields. CONCLUSIONS: In an elderly patient receiving digitalis, the development of photopsia characterized by innumerable points of light in the peripheral visual fields or a decrease in visual acuity raises the possibility that the patient's visual disturbance may have been digitalis induced. Digitalis-induced visual disturbances other than chromatopsia or disturbances of color vision may occur in elderly patients who have no other clinical manifestations of digitalis intoxication and who have a serum digitalis concentration within or below the therapeutic range.