Projections of the central medial nucleus of the thalamus in the rat: node in cortical, striatal and limbic forebrain circuitry.

The central medial nucleus (CM) of thalamus is a prominent cell group of the rostral intralaminar complex of the thalamus. No previous report in the rat has comprehensively described the projections of CM. Using the anterograde anatomical tracer, Phaseolus vulgaris leucoagglutinin, we examined the efferent projections of CM, comparing projections from rostral (CMr) and caudal (CMc) regions of CM. We showed that the central medial nucleus distributes substantially to several cortical sites and to a limited number of subcortical structures. The primary CM targets were anterior and posterior regions of cortex, the claustrum, the caudate-putamen, the nucleus accumbens (ACC), the olfactory tubercle, and the amygdala. CMr and CMc distribute to several of the same structures but essentially to different parts of these structures. By comparison, CMr more strongly targets limbic structures, CMc more heavily sensorimotor structures. Main CMr projection sites were the medial agranular, anterior cingulate, prelimbic, dorsolateral orbital and dorsal agranular insular cortices, the dorsal striatum, the ACC, and the basolateral nucleus of the amygdala. Main CMc cortical projection sites were the ventrolateral, lateral and dorsolateral orbital cortices, dorsal, ventral and posterior agranular insular cortices, visceral cortex, primary somatosensory and motor cortices, and perirhinal cortex. Main CMc subcortical projection sites were the dorsal striatum and the lateral, central, anterior cortical, and basomedial nuclei of amygdala. The largely complementary output of CMr and CMc to diverse areas of cortex and to regions of the striatum and amygdala suggest a combined CM influence over a widespread area of the anterior cortex and throughout the dorsal and ventral striatum and the amygdala. CM projections to limbic and sensorimotor structures of the rostral forebrain suggest that CM may serve to integrate affective, cognitive and sensorimotor functions for goal-directed behavior.

Effects of BioChlor and Fermenten on microbial protein synthesis in continuous culture fermenters.

Meta analysis models were constructed from a data-set of 15 continuous culture fermenter trials and 118 observations on studies with either BioChlor (n = 23 observations) or Fermenten (n = 95) included at 10 and 3%, respectively, of dietary dry matter (DM) to evaluate effects of the ingredients BioChlor and Fermenten (B/F) on rumen function. Digestibility of crude protein was significantly increased by 11% with B/F treatment. This was reflected in significant increases in digestibility of DM and organic matter (OM) by 3.6 and 7.9%, respectively. Increased amounts of sugar in the diet in the presence of B/F tended to reduce digestibility of non-structural carbohydrates (NSC); however, the net effect on NSC digestion was small. There was no effect of treatment on most individual volatile fatty acids (VFA) or total VFA production. Propionate production, however, was significantly reduced in treated fermenters. The main effect of B/F as well as of starch and soluble fiber when combined with the treatment was to increase propionate production; however, the interaction between B/F treatment and sugar decreased propionate production markedly, resulting in a net decrease. The acetate-to-propionate ratio increased by 6% with B/F, largely as a result of the decrease in propionate. Production of nonammonia nitrogen was 1% less in B/F-treated fermenters, and interactions between treatment and starch, sugar, or soluble fiber were significant. Treated fermenters produced 15.7% more microbial nitrogen, in association with a significant 37% increase in rumen protein digestion. Interactions between treatment and starch, soluble fiber, or sugar influenced these results. The interaction of B/F and sugar resulted in a decrease in undegradable protein N and an increase in microbial nitrogen production. Ammonia nitrogen concentrations were increased by 24.6% in treated fermenters. Efficiency of microbial nitrogen production from DM, OM, or carbohydrate was significantly increased by B/F. Sugar content increased efficiency of microbial protein production/kg of OM digested or carbohydrate digested in the presence of treatment by >10 times the increase that was attributable to the interaction of treatment with starch. Treatment with B/F reduced moles of VFA produced/kg of microbial nitrogen produced by 16%. This effect was also substantially influenced by interactions between B/F and sugar. If the fermenter results are representative of those in vivo, milk production responses to treatment with B/F will depend on amounts of starch, soluble fiber, and, particularly, sugar in diets. Milk production responses will also depend on the quality of protein in the diet and the comparative benefit that increased flux of microbial nitrogen provides. Increased digestibility of OM should allow additional ruminant production benefits.

Biohydrogenation of unsaturated fatty acids in continuous culture fermenters during digestion of orchardgrass or red clover with three levels of ground corn supplementation.

Diet digestibility and outputs of biohydrogenation intermediates were assessed in a continuous culture of ruminal microorganisms. Orchardgrass or red clover harvested and frozen during spring or fall served as the primary substrates for fermentation. During 10-d incubations, fermenters were fed thawed forage (50 g of DM/d), forage (42 g/d) plus 8 g/d of corn, or forage (34 g/d) plus 16 g/d of corn. Effluents from the last 3 d of incubation were composited for analyses. Starch input increased from 5 to 27% of DM as corn input increased from 0 to 16 g/d. Corn input reduced (P < 0.01) pH, increased (P < 0.01) microbial DM yield, and increased (P = 0.01) digestibility of DM, NDF, CP, and nonstructural carbohydrates. Overall, apparent hydrogenation (percentage) of cis9-18:1, 18:2n-6, and 18:3n-3 was greater (P < 0.05) with orchardgrass than clover. Hydrogenation of cis9-18:1 and 18:2n-6 increased (P = 0.01), but hydrogenation of 18:3n-3 decreased (P = 0.01) linearly due to corn input, regardless of forage. As a result, output of trans11, cis15-18:2 also decreased (P = 0.01). Average output of cis9,trans11-18:2 was greater (P = 0.01) for clover (1.3 mg/d) compared with orchardgrass (0.6 mg/d), but corn input with either forage increased (P = 0.01) cis9,trans11-18:2 output by 205%. Output of trans11-18:1 was greater (P = 0.01) from orchardgrass compared with clover (174 vs. 90 mg/d), but corn increased (P = 0.01) trans11-18:1 output only from clover fermentations. Output of trans10-18:1 was greater (P = 0.01) in response to orchardgrass compared with clover (10 vs. 4 mg/d), but corn addition doubled the output regardless of forage type. Output of trans10,cis12-18:2, which did not differ due to forage type, increased (P = 0.01) twofold in response to corn. Cis9,cis11-18:2 was a primary conjugated isomer produced from forage fermentations, but its output decreased (P = 0.03) in response to corn input. When inputs of 18:2n-6 plus 18:3n-3 were less than 0.9% of total DM (clover), hydrogenation was low (87%). When 18:2n-6 plus 18:3n-3 inputs were from 1.2 to 1.5% of total DM (orchardgrass), hydrogenation averaged 96%. Despite greater hydrogenation, incremental additions of cis9-18:1 and 18:2n-6 from corn grain increased (P < 0.05) outputs of trans10-18:1, trans11-18:1, trans10,cis12-18:2, cis9,trans11-18:2, and trans,trans-18:2 in effluent. Results suggest that forage species alone or in combination with corn grain can alter hydrogenation and profiles of intermediates to varying degrees.

Influence of yeast culture on ruminal microbial metabolism in continuous culture.

A continuous culture study was conducted to evaluate the effect of two different yeast cultures on ruminal microbial metabolism. The treatments were a) control lactation ration, b) yeast culture 1 (YC1, Diamond-V XP) and c) yeast culture 2 (YC2, A-Max), both fed at an equivalent of 57 g/head per day. The results showed that both yeast culture products increased dry matter (DM) digestion, propionic acid production, and protein digestion compared with the control. Yeast culture 1 demonstrated an increase in molar percentage of propionic acid, a reduction in acetic acid, and a lower mean nadir (daily low) pH compared with YC2. Ruminal cultures treated with YC digested more protein and contributed less bypass N than control. Supplementing YC2 resulted in a tendency for higher microbial N/kg DM digestion than YC1. Yeast culture 1 resulted in production of rumen microbes containing less protein and more ash than YC2. These results support previous research findings that yeast culture does influence microbial metabolism, and specific yeast cultures may have different modes of action.

Chaos, ergodic convergence, and fractal instability for a thermostated canonical harmonic oscillator.

The authors thermostat a qp harmonic oscillator using the two additional control variables zeta and xi to simulate Gibbs' canonical distribution. In contrast to the motion of purely Hamiltonian systems, the thermostated oscillator motion is completely ergodic, covering the full four-dimensional [q,p,zeta,xi] phase space. The local Lyapunov spectrum (instantaneous growth rates of a comoving corotating phase-space hypersphere) exhibits singularities like those found earlier for Hamiltonian chaos, reinforcing the notion that chaos requires kinetic-as opposed to statistical-study, both at and away from equilibrium. The exponent singularities appear to have a fractal character.

Feasibility of electrokinetic soil remediation in horizontal Lasagna cells.

An integrated soil remediation technology called Lasagna has been developed that combines electrokinetics with treatment zones for use in low permeability soils where the rates of hydraulic and electrokinetic transport are too low to be useful for remediation of contaminants. The technology was developed by two groups, one involving industrial partners and the DOE and another involving US EPA and the University of Cincinnati, who pursued different electrode geometries. The Industry/DOE group has demonstrated the technology using electrodes and treatment zones installed vertically from the soil surface. We have demonstrated the feasibility of installing horizontal electrodes and treatment zones in subsurface soils by hydraulic fracturing, a process that we adapted from petroleum industry practices. When horizontal electrodes were connected to a dc power supply, uniform electrical potential gradients of 10-40 V/m were created in soil between the electrodes, inducing electroosmotic flow that facilitated movement of water and contaminants into treatment zones between the electrodes.

Degradation of two protein sources at three solids retention times in continuous culture.

Effects of solids retention times (SRT) of 10, 20, and 30 h on protein degradation and microbial metabolism were studied in continuous cultures of ruminal contents. Liquid dilution rate was constant across all retention times at .12 h(-1) (8.3 h mean retention time). Two semipurified diets that contained either soybean meal (SBM) or alfalfa hay (ALFH) as the sole nitrogen source were provided in amounts that decreased as SRT was increased. Digestion coefficients for DM, NDF, and ADF increased with increasing SRT. Digestion coefficients for nonstructural carbohydrates were higher in the SBM diet than in the ALFH diet but were not affected by SRT. Protein degradation in the ALFH diet averaged 51% and was unaffected by retention time. In the SBM diet, digestion of protein was 77, 78, and 96% at 10-, 20-, and 30-h retention times, respectively. Microbial efficiency decreased with increasing SRT and was greater for the SBM than for the ALFH diet. Efficiencies ranged from 30.6 to 35.7 and 20.8 to 29.2 g of N/kg of digested DM for the SBM and ALFH diets, respectively, as SRT decreased from 30 to 10 h. The diaminopimelic acid content of the microbes increased as SRT increased, indicating that changes in microbial species occurred owing to passage rates. From these results, we concluded that the digestibility decreases associated with increased ruminal turnover rates may be less for nonstructural carbohydrates and protein than for the fiber fractions.

Immunologic and virologic responses to HAART in severely immunocompromised HIV-1-infected children.

OBJECTIVE: To determine the long-term immunologic and virologic effects of highly active antiretroviral therapy (HAART) in children with AIDS. DESIGN: A prospective observational study. SETTING: Two pediatric HIV clinics. PARTICIPANTS: Twenty-five protease-inhibitor naive HIV-infected children (aged 2-18 years) with advanced disease (CD4 < or =6%). INTERVENTION: HAART (one protease inhibitor and one or more nucleoside analogs). Diphtheria and tetanus immunization in six patients after 18 months of therapy. MAIN OUTCOME MEASURES: Changes in percentage of CD4 cells and plasma HIV-1 RNA levels; post-treatment assays of lymphoproliferative responses to recall antigens; CD4 cell memory phenotype. RESULTS: Median duration of follow-up was 18.8 months (range, 7.5-28 months). At baseline the CD4 cell percentage was 2% (range, 0-6%), this increased significantly to 16% (range, 3-48%) above baseline at 12 months (P = 0.002). The mean maximum CD4 cell increase was 20.7% (range 4-48%) which corresponds to 657x10(6) cells/l (range, 30-2240x10(6) cells/l) above baseline. By contrast, the median viral load was not significantly lower at 12 months than at baseline (P = 0.34), and only 25% of the patients had sustained undetectable viral load. Of the reconstituted CD4 cells 70% were naive, and none of the subjects had lymphoproliferative responses to tetanus and diphtheria although 40% did develop responses to Candida, an environmental antigen. A single immunization with diphtheria and tetanus toxoid produced lymphoproliferative responses to tetanus in three out of six patients. CONCLUSIONS: HAART was associated with sustained increases in CD4 cell counts, despite a high incidence of 'virologic failure'. CD4 counts and the proportion of naive cells were higher than have been reported in adults, which may be a reflection of greater thymic activity in children. Memory cell clones for antigens encountered in the past which are not prevalent before therapy could not be expanded without additional antigenic exposure.

Effects of concentrations of peptides on microbial metabolism in continuous culture.

Effects of peptide concentrations on microbial metabolism were investigated using a basal diet in which peptides replaced urea as a N source at levels of 0, 10, 20, and 30% of total N. The basal diet contained 17.8% CP and 46% nonstructural carbohydrates. Each diet was provided to continuous cultures of rumen contents operating at liquid and solids flow rates of 12 and 4.5%/h, respectively. Production of microbial CP and digestion of DM and protein were affected quadratically by peptide addition, with the highest values for each variable on the diet containing 10% peptides. Fiber digestion decreased linearly with peptide addition. The depressed fiber digestion and microbial CP production at peptide concentrations > 10% seemed related to a linear decrease in ammonia concentration in the fermenters as peptide levels increased. Peptide-amino acid N recovered in the supernatant fluid did not increase with increasing peptides, because peptide uptake by the microbes increased as peptide concentrations increased. Even though the efficiency of conversion of peptide N to microbial CP increased with increasing peptides, there was no change in grams of microbial N produced per kilogram of OMD. We suggest that in diets high in nonstructural carbohydrates, excessive peptides can depress protein digestion and ammonia concentrations, resulting in decreased OMD, fiber digestion, and total microbial CP production.

Effect of form of nitrogen on growth of ruminal microbes in continuous culture.

A study was conducted to determine the effect of various forms of N on the growth of ruminal microbes in a continuous culture system with solids and liquid dilution rates comparable to those of a high-producing dairy cow. Nitrogen forms were isolated soy protein, soy peptides, individual amino acids (AA) blended to profile soy protein, and urea, which were fed alone and in combinations so that the total N provided was 1.6% of the diet DM. The 100% soy protein treatment resulted in reduced digestion of N and nonstructural carbohydrate compared with other N forms, and outflow of bacterial N/24 h was less than when peptides were fed. This suggested that proteolysis rather than peptide uptake was the rate-limiting step in N utilization in this study. Non-urea N forms increased ADF digestion, total VFA production and the molar percentages of isobutyrate, isovalerate, and valerate compared to urea, which reflected the contribution of carbon skeletons of AA. When combinations of N forms were used, each form contributed an equal quantity of N, 50% of the total treatment, which was .8% of the diet DM. Combinations of N forms did not enhance, and in most cases reduced, ADF and NDF digestion when compared with individual N forms, and no combinations increased microbial growth over that of the individual forms. These results confirm that N forms other than ammonia are needed not only for maximum microbial growth, and they further demonstrate a need for non-protein N for the fiber digestion. In addition, results of this study suggest a requirement for a minimum level of peptide or AA N, which was met only when individual N forms were fed.

CD31 immunoreactivity in mesenchymal neoplasms of the skin and subcutis: report of 145 cases and review of putative immunohistologic markers of endothelial differentiation.

CD31 has recently been reported as a specific marker of endothelial differentiation among non-hematopoietic human neoplasms. In order to address this contention in particular regard to tumors of the skin and subcutis, the authors undertook a comparative study that surveyed 145 mesenchymal lesions. The antibodies used were directed against CD31 (clone JC/70A) and CD34 (clone My10), and these were compared with binding of Ulex europaeus I agglutinin (UEA). Proliferations that were included in the category of vascular tumors included cavernous and capillary hemangiomas (17 cases); lymphangiomas (8); epithelioid ("histiocytoid") hemangiomas (3), papillary endovascular hemangioendothelioma (1), angiosarcoma (7), and Kaposi's sarcoma of the mixed angiomatoid and spindle-cell type (17). CD31-immunoreactivity was observed in 35 of 53 vascular lesions; the neoplastic cells in a single angiosarcoma and the spindle cells in each case of Kaposi's sarcoma (KS) were not labeled. In all of the latter tumors, however, staining for CD31 was identified in the endothelia of angiomatoid areas and non-neoplastic blood vessels. These results compared favorably with those seen with anti-CD34, which decorated 36 of 53 vascular tumors--including 8 of 17 KS cases--and UEA, which bound to the neoplastic cells of 36 lesions. In contrast, all of 92 non-endothelial tumors included in this study (34 nerve sheath tumors [30 benign; 4 malignant]; 39 fibrohistiocytic neoplasms [11 benign; 28 malignant]; 9 smooth muscle tumors [6 benign; 3 malignant]; 7 glomus tumors; and 3 giant cell fibroblastomas) were negative for CD31. UEA labeled 3 non-vascular neoplasms, whereas 38 lesions of that type were CD34-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolated toxoplasmosis of the thoracic spinal cord in a patient with acquired immunodeficiency syndrome. Case report.

Toxoplasmosis and lymphoma are the two most common causes of intraparenchymal cerebral mass lesions in patients with acquired immunodeficiency syndrome (AIDS). The clinical and radiographic features of the intracranial lesions have been well described. Because of the high frequency of toxoplasmosis in the AIDS population, common therapy for patients presenting with intracranial mass lesions consists of an empirical trial of anti-Toxoplasma chemotherapy, with biopsy reserved for cases demonstrating features considered to be more consistent with lymphoma, or for lesions that do not improve despite adequate anti-Toxoplasma treatment. A similar treatment algorithm does not exist for intramedullary lesions of the spinal cord. The authors describe a patient who presented with paraparesis resulting from an isolated thoracic intramedullary lesion. An open biopsy of the lesion revealed characteristic structures containing Toxoplasma tachyzoites. The clinical and radiographic presentation of the lesion is discussed, the available literature is reviewed, and a treatment strategy for spinal cord lesions in AIDS patients is proposed.

Endoscopic sphincterotomy in the management of posttraumatic biliary fistula.

Complications after nonoperative management of hepatic trauma are rare but include persistent biliary fistula in 4% of cases. Therapy usually involves surgical drainage or hepatic resection to control the fistula. The authors present a case of hepatic biliary fistula treated nonoperatively with percutaneous drainage and endoscopic sphincterotomy. A 16-year-old girl suffered a grade III parenchymal liver fracture to the right lobe in an automobile accident. She was hemodynamically stable with no coexistent injuries and was treated nonoperatively. Over 2 weeks her total bilirubin rose to 3.2 mg/dL, and alkaline phosphatase was 463 U/L. Ultrasound showed free intraperitoneal fluid, and 2 L of bilious fluid were retrieved by paracentesis. A radionuclide scan confirmed massive extravasation of isotope from the right lobe. Two drains percutaneously placed over the parenchymal fracture produced 500 to 600 mL of bile daily. Endoscopic retrograde cholangiopancreatography (ERCP) 1 week later showed a normal extrahepatic biliary system. A 1-cm sphincterotomy was performed without difficulty. Within 72 hours, percutaneous drains produced only 35 mL per day. The follow-up radionuclide scan showed no evidence of extrahepatic biliary extravasation, and 3 weeks later the drains were removed. Six months after the accident, results of the computerized tomography scan and liver function tests were normal. It was believed that endoscopic sphincterotomy reduced fistula output by decreasing the intrabiliary pressure caused by the ampulla, thus favoring internal drainage. This case demonstrates the effectiveness of endoscopic sphincterotomy as an alternative to direct surgical intervention for the management of posttraumatic biliary fistula.

Interactions of fiber and nonstructural carbohydrates on lactation and ruminal function.

Four Holstein cows averaging 147 DIM and fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square trial to determine diet effects on DMI, milk production, and ruminal metabolism. Diets contained either rapidly or slowly degraded NDF, referred to as low fill and high fill, respectively, combined with two percentages of nonstructural carbohydrate. Treatments were 39% nonstructural carbohydrate (low or high fill) and 29% nonstructural carbohydrate (low or high fill). Intake of DM was not affected by either fill or nonstructural carbohydrate. Ruminal NDF digestibilities averaged 43.1 and 35.6% for the low fill and high fill diets, respectively. Ruminally digested nonstructural and total carbohydrate increased, but milk production decreased, as nonstructural carbohydrate increased from 29 to 39% in diets. Liquid and solid ruminal passage rates, as measured by Co-EDTA and Yb, respectively, were reduced by either 39% nonstructural carbohydrate or low fill diets. Lower microbial N flow to the duodenum and lower efficiency of microbial growth also were observed for diets with 39% nonstructural carbohydrate. The combination of 39% nonstructural carbohydrate and rapidly degraded fiber gave the highest DM and nonstructural carbohydrate digestion in the rumen but resulted in low microbial N synthesis per day and the least microbial N per kilogram of OM digested.

Antimicrobial activity and spectrum of rifaximin, a new topical rifamycin derivative.

Rifaximin, a rifamycin derivative, was evaluated in vitro to assess its spectrum and potency against a wide variety of bacteria, yeasts, viruses, and parasites. High concentrations of rifaximin were often used to reflect topically achieved levels since this compound is poorly absorbed by oral route. Like rifampin, rifaximin possessed best activity against Staphylococcus spp. (MIC50 < or = 0.015 microgram/ml), Streptococcus spp. (MIC50s, < or = 0.03-0.12 microgram/ml), Enterococcus spp. (MIC50s, 0.25-2 micrograms/ml), Bacillus cereus (MIC50, 0.06 microgram/ml), Moraxella catarrhalis (MIC50, < or = 0.03 microgram/ml), and Haemophilus influenzae (MIC50, 0.25 microgram/ml). Rifaximin demonstrated potential use as a topical agent for bacterial vaginosis by inhibiting Bacteroides bivius-disiens, Gardnerella vaginalis, Lactobacillus spp., and Mobiluncus spp. strains (all MICs < or = 1 microgram/ml). Strains of Haemophilus ducreyi and Neisseria gonorrhoeae (MIC50s, 0.25 microgram/ml) were also inhibited. However, some organisms associated with genital tract infections were rifaximin resistant, for example, Candida spp., herpes virus, mycoplasmas, Trichomonas vaginalis, and Ureaplasma urealyticum. Clinical trials appear warranted using rifaximin topical concentrations that will minimize mutations to rifamycin resistance.

Viscous attractor for the Galton board.

We analyze the Galton Board [or periodic "Lorentz Gas"] with a point mass scattered by elastic disks of diameter sigma, using a constant driving field g and a constant-viscosity linear drag force -p/tau, where p is the point-mass momentum. This combination leads to a nonequilibrium steady state which depends only upon the dimensionless ratio gtau(2)/sigma. The long-time-averaged trajectory leads to multifractal phase-space structures closely resembling those we found earlier using isokinetic equations of motion derived from Gauss' Principle of Least Constraint. A highly damped [small tau] creeping-flow limit describes our results for gtau(2)/sigma less than about 0.2. The lightly damped Green-Kubo linear-response limit for the model provides an accurate description of the dissipative dynamics for gtau(2)/sigma greater than about 2.0.

Early diagnosis of human immunodeficiency virus infection in children less than 6 months of age: comparison of polymerase chain reaction, culture, and plasma antigen capture techniques.

Three techniques were evaluated for their ability to detect human immunodeficiency virus (HIV) in infants from birth to 6 months of age. Polymerase chain reaction (PCR) and HIV cocultivation were of comparable sensitivity, detecting 90% of all positive specimens. Both techniques found positive results in approximately 5% of samples from seroreverting children. Both assays detected HIV in only half of infected newborns, suggesting that this fraction of children was infected during gestation. Plasma p24 antigen was detected in three-fourths of all samples tested but in only half of infected children during the first 2 months of life and 88% of samples from children during the next 4 months. The specificity of p24 antigen detection was 100%.

Diagnosis of pulmonary arteriovenous malformation by ultrafast chest computed tomography in Rendu-Osler-Weber syndrome with cerebral ischemia--a case report.

Pulmonary arteriovenous malformations occur in 15-20% of patients with Rendu-Osler-Weber syndrome and can be the source of paradoxical emboli causing cerebral ischemia, septic emboli leading to brain abscesses, or polycythemia causing hyperviscosity and cerebral ischemia. The diagnosis of these malformations may be elusive, since classic clinical or radiologic findings may be absent in some patients. The authors report a patient with Rendu-Osler-Weber syndrome with cerebral ischemia who had normal findings from a pulmonary examination and chest roentgenogram. An ultrafast computed tomography scan of the chest demonstrated, however, a pulmonary arteriovenous malformation in the right upper lobe that was successfully resected. Ultrafast computed tomography of the chest is a relatively noninvasive method of screening for a pulmonary arteriovenous malformation in a patient with Rendu-Osler-Weber syndrome and otherwise unexplained neurologic symptoms.

Clarithromycin in vitro activity enhanced by its major metabolite, 14-hydroxyclarithromycin.

14-Hydroxyclarithromycin, an active metabolite of clarithromycin, was compared for antimicrobial activity alone and in combination with the parent compound. The 14-hydroxyclarithromycin potency was comparable to that of clarithromycin, but was more active against Haemophilus influenzae (MIC50, 1 microgram/ml). Combination MICs at pharmacokinetic ratios produced end points equal to the most active component of the combination. However, checkerboard MICs and kill-curve studies suggested enhanced interactive effects. Partial synergy and additive interactions were demonstrated in 96% of strains tested with synergy (partial) most often observed among the Enterococcus faecalis, H. influenzae, and staphylococci. To determine the best in vitro test methods for predicting the value of 14-hydroxyclarithromycin, combination disks or ratio MIC tests may not be practical. A modification of the proposed clarithromycin-susceptible breakpoint (less than or equal to 2 micrograms/ml) upward to less than or equal to 4 micrograms/ml (greater than or equal to 14 mm) was suggested to recognize the additional activity contributed by the 14-hydroxy metabolite. This modification should be applied, limited to susceptibility tests of H. influenzae and possibly the enterococci.

Balancing carbohydrates and proteins for optimum rumen microbial yield.

Establishing conditions under which rumen fermentation will be optimized requires an understanding of the nutrient requirements of the mixed microbial population. The major nutrients required by rumen microbes are carbohydrates and proteins, but the most suitable sources and quantities needed to support maximum growth have not been determined. Digestion of proteins results in the production of peptides, which can accumulate in the rumen. Peptides are further hydrolyzed to amino acids, some of which are deaminated, producing ammonia. Although peptides, amino acids, and ammonia all may individually serve as sources of N for various microbes, the total population achieves the highest growth rate on mixtures of all three sources. In a somewhat analogous manner, carbohydrates are digested by exoenzymes to oligosaccharides that are available for crossfeeding by the mixed microbial population. Based on data from both in vitro and in vivo studies, there is general agreement that rate of digestion of carbohydrates is the major factor controlling the energy available for microbial growth; in addition, rate of digestion of total carbohydrate is directly related to proportion of starches, pectins, and sugars. Proteins affect both total fermentation and production of microbial DM per unit of carbohydrate fermented. It appears that the quantity of ruminally available protein needed to optimize microbial growth may, under some conditions, be as high as 14 to 15% of diet DM.