Forms of human milk folacin and variation patterns

The pattern of folacin in 180 human milk samples collected from 16 women was studied before and after pteroylglutamic hydroxylase (conjugase) treatment. The differential response of Lactobacillus casei versus Streptococcus faecalis distinguishes N-5-methyltetrahydrofolate from other forms. Growth of Pediococcus cerevisiae differentiates the reduced monoglutamates, other than the N-5-methylated derivative, from oxidized folacins. Mean folacin activity with L. casei was 85.3 ng/ml. Prior to conjugase treatment of samples, mean activity was 46.9 ng/ml with this organism. The responses of S. faecalis and P. cerevisiae were 48% and 7.6%, respectively, of the total L. casei active folacins. The total L. casei active folacins increased from 76.5 ng/ml at 6 weeks of lactation to 97.1 ng/ml at 12 weeks of lactation. Increases were also observed with time of day: from morning (65.7 ng/ml), to afternoon (80.0 ng/ml), and to evening (114.7 ng/ml). Hindmilk had greater total L. casei activity (100.0 ng/ml) than foremilk (73.8 ng/ml). Although folacins active for S. faecalis and P. cerevisiae were not affected by duration of lactation, increases in folacin activity with time of day and from fore- to hindmilk were observed using both of these organisms. Values for the folacin content of human milk are therefore dependent on sampling procedures. Pteroylpolyglutamates of greater than or equal to 3 glutamic acid residues and N-5-methyltetrahydrofolate are the predominant forms of human milk folacin based on differential growth responses of L. casei, S. faecalis, and P. cerevisiae to these forms.

Muramyl dipeptide protects decomplemented mice from surgically-induced infection

Muramyl dipeptide (MDP) is a natural product of bacterial cell-wall breakdown, which can now be produced synthetically; it is the smallest component of the mycobacterial cell wall capable of reproducing the adjuvant activities of Freund's complete adjuvant. We tested the well-documented, protective effect of MDP to increase survival in a murine model simulating surgically-induced bacteremia. The protocol involved the bacterial innoculation of control and decomplemented mice in the presence and the absence of pretreatment with MDP. Bacteremia in both the control and decomplemented groups pretreated with MDP was decreased statistically at 24 h (P less than 0.01) as compared to controls. Likewise, survival was increased significantly at 24 h (P less than 0.05), 48 h (P less than 0.001), and 72 h (P less than 0.001) using the same group comparisons. We conclude, therefore, that MDP maintains its protective effect in the absence of complement, supporting the view that the mechanism of action of MDP is complement independent.

Antihypertensive aminotetralins related to labetalol and medroxalol

A series of compounds was prepared in which the 1-methyl-3-phenylpropylamino moieties of the antihypertensive agents labetalol and medroxalol were replaced by 2-aminotetralins. Compounds containing a 6-methoxy and 6,7-methylenedioxy group in the aminotetralin were at least as active as labetalol in lowering the blood pressure of the spontaneously hypertensive rat (SHR). As determined by ligand binding, these compounds were comparable to labetalol as alpha 1-antagonists but were substantially weaker beta 1-antagonists.

EQUIL2: a BASIC computer program for the calculation of urinary saturation

A BASIC computer program for the calculation of urinary supersaturation with respect to the common kidney stone components is described. In vitro and in vivo tests show that the program described accurately calculates supersaturation. The application of this computer program to urolithiasis research is discussed.

Retropharyngeal infections in five horses

Five horses with retropharyngeal (RP) infections had clinical signs of dysphagia and/or dyspnea. Diagnosis was confirmed, using pharyngeal endoscopy and lateral radiography of the pharynx. One horse responded to surgical drainage of a RP abscess and was sound at light work. One horse responded to medical management after the site of infection was surgically explored. Two horses recovered after medical management; the RP abscess of 1 of these 2 horses ruptured spontaneously into the pharynx and the other horse became racing sound. The fifth horse remained dysphagic and had left laryngeal hemiplegia after medical treatment.

Acquired cardiovascular disease

This article reviews the etiology, clinical findings, and significance of diseases of the heart valves, myocardium, pericardium, and great vessels of the horse. Each valve is considered separately from the point of view of murmur production. In addition, the role of the cardiovascular system in the etiology of sudden and unexpected death is considered.

Deficiency of the contact phase of intrinsic coagulation in a horse

A 16-year-old gelding was examined because of weight loss, inappetence, and intermittent fever of 2 months' duration. Preliminary laboratory findings revealed anemia, hypoproteinemia, thrombocytopenia, and prolongation of the activated partial thromboplastin time. A deficiency or inhibition of coagulation factor XI, factor XII, or high molecular weight kininogen was diagnosed. This defect was not associated with a bleeding diathesis, but should be considered as a cause of prolongation of the activated partial thromboplastin time.

Fiberoptic gastroduodenoscopy in the horse

A method of fiberoptic gastroduodenoscopy and biopsy was developed for use in large horses. A 275 cm X 13.5 mm fiberendoscope was used to examine the stomach and proximal portion of the duodenum. Food was withheld for 24 to 48 hours before examination. In more than 50 horses, gastric and duodenal structures were easily visualized. A variety of lesions was detected, including parasitic lesions, gastric ulcers, gastric neoplasia, and pyloric stenosis. Mucosal biopsy specimens were obtained in selected cases.

Staphylococcal lysate fails to elicit nonspecific immune enhancement in a simulated surgical infection

Staphylococcus aureus produces a delayed-type hypersensitivity reaction, which results in some degree of nonspecific immune enhancement. The authors chose to observe the effects of staphylococcal vaccine (staphage lysate) as a possible potentiator of nonspecific immunity. The experiments were performed in a well-known model simulating surgical infection. The experimental results do not support the previously proposed hypothesis that staphylococcal vaccine improves the immune response to a bacterial challenge.

Effects of calcium on cholinergic-stimulated gastrin release in the rat

The effects of alterations in availability and access of extracellular media calcium on antral gastrin release were examined in the basal state and in response to cholinergic stimulation in rat antral organ culture experiments. In the presence of either divalent cationic chelator (EGTA) or calcium channel blocker (verapamil, nifedipine), carbachol-stimulated gastrin release was inhibited completely to values that were not significantly different from non-stimulated control. In the absence of added calcium chloride, carbachol stimulated gastrin release during the initial 30 min of culture but not at 69 and 120 min of culture. Inhibition by EGTA and verapamil of carbachol-stimulated gastrin release during the initial 30 min of culture suggests, but does not prove, that these agents may also effect intracellular availability and movement of calcium. Cholinergic stimulation of gastrin release demonstrated a concentration-dependent relationship with extracellular calcium: optimal culture media calcium concentration was 1 mM. In conclusion, these studies indicate that cholinergic stimulation of the gastrin cell requires availability of extracellular calcium.

Computer Vision and Natural Constraints

Computer vision, the automatic construction of scene descriptions from image input data, has just entered its second decade. Approaches have varied widely, especially in the amounts of symbolic, domain-dependent knowledge and inference that are incorporated into the vision process. Much current research addresses the extraction of physical properties of the scene (depth, surface orientation, reflectance) from images by using only a few general assumptions about the scene domain. Extraction of physical parameters is part of a hierarchy of operations needed to transform image input data to symbolic descriptions. Two other processes that serve as examples are stereo fusion and the partitioning of image phenomena into related groups. Computer vision research is influencing theories of animal perception as well as the design of computing architectures for artificial intelligence.

L-Rhamnose utilisation in Salmonella typhimurium

L-Rhamnose is degraded by strains of Salmonella typhimurium by isomerisation to L- rhamnulose , phosphorylation to L- rhamnulose -1-phosphate and cleavage to lactaldehyde and dihydroxyacetone phosphate. The enzymes involved are, respectively, rhamnose isomerase ( RhaI ), rhamnulokinase ( RhuK ) and an aldolase (Ald). Strains able to grow rapidly on L-rhamnose contained a high-affinity uptake system for 3H-L-rhamnose that was induced by L-rhamnose and repressed by D-glucose. The synthesis of RhaI and RhuK was also induced by L-rhamnose but was not repressed by D-glucose. The synthesis of Ald was constitutive. Data are presented on some strains which grow very slowly on L-rhamnose and on others which do not utilise it.

Differences in the control of virus mRNA splicing during permissive or abortive infection with influenza A (fowl plague) virus

Spliced transcripts of influenza A (fowl plague) virus (FPV) RNA (vRNA) segments 7 and 8 accumulate to a much greater extent during non-productive infection of mouse L cells, than they do during productive infection in primary chick embryo fibroblasts (CEF). Virus-specific protein synthesis, or a consequent event in virus replication appears necessary to promote splicing of vRNA segment 8-encoded mRNAs in both cell types, and of vRNA segment 7-encoded mRNAs in CEF. In L cells, however, splicing of the segment 7-encoded mRNAs seems to be independent of such virus-specific control. This observation is discussed in relation to the defect in expression of vRNA 7 which has been observed previously in FPV-infected L cells, and which is thought to account for the failure of virus replication.

3-methylindole as a model of equine obstructive lung disease

3-methylindole was administered orally and intravenously to horses and ponies in order to determine the ability of this chemical to provide a model of equine pulmonary disease. Both routes produced a severe and sometimes fatal pulmonary disease, characterised by bronchiolitis. Clinical signs developed 48 to 72 h after dosing and were most severe between Days 4 and 10 post dosing. Intravenous administration of 3-methylindole produced lung injury more rapidly and at a lower dose rate than the oral route. It is suggested that the respiratory condition induced by this chemical could become a method for standardisation of lung function techniques and interpretation in equine obstructive pulmonary disease.

Suspected hepatotoxicity in neonatal foals: preliminary report of an emerging syndrome

An apparently new and emerging fatal hepatic disease affecting foals is described. Characteristics included evidence of hepatic failure, marked biliary hyperplasia, hepatocellular necrosis and occasionally fibrosis. Generally, the features of the disease appear to differ markedly from other hepatic diseases of neonatal foals.

Adenosine relaxes the aorta by interacting with an A2 receptor and an intracellular site

The purpose of this study was to determine whether the adenosine receptor that mediates relaxation of the noradrenaline-contracted guinea-pig aorta is of the A1 or A2 subtype. 5'-N-ethylcarboxamide adenosine (NECA) and 5'-N-cyclopropylcarboxamide adenosine (NCPCA) were about 100 times more potent as relaxants of the aorta than L-N6-phenylisopropyladenosine (L-PIA) and N6-cyclohexyladenosine. L-PIA was 3 times more potent than D-PIA. These relaxations were not altered by the purine transport inhibitor dipyridamole, but were attenuated by the cell surface adenosine receptor antagonist 8-phenyltheophylline. Adenosine and 2-chloroadenosine differed from NECA and NCPCA since they evoked greater maximal relaxations and their submaximal responses were less sensitive to blockade by 8-phenyltheophylline. These differences were abolished by dipyridamole which indicates that they were due to an intracellular action of adenosine and 2-chloroadenosine. The intracellular 'P-site' agonist, 9-beta-D-xylofuranosyladenine evoked small relaxations that were attenuated by dipyridamole but were unaffected by 8-phenyltheophylline. These results indicate that adenosine can relax the aorta via interactions with a cell surface A2 receptor and with an intracellular site.

Adenosine A1 receptor mediated inhibition of nerve stimulation-induced contractions of the rabbit portal vein

The aim of this study was to determine whether the adenosine receptor that inhibits adrenergic neurotransmission in the rabbit portal vein is of the A1 or the A2 subtype. Isometric contractions of the isolated vein were evoked by electrical field stimulation and by exogenous noradrenaline. Low concentrations of adenosine, and a number of analogues inhibited the response evoked by field stimulation but had no effect on those evoked by noradrenaline. The order of inhibitory potency was: L-N6-phenylisopropyladenosine (L-PIA) = N6-cyclohexyladenosine (CHA) = 5'-N-cyclopropylcarboxamide adenosine (NCPCA) greater than or equal to 5'-N-ethylcarboxamide adenosine (NECA) = 2-chloroadenosine greater than adenosine greater than D-PIA. The difference in potency between the stereoisomers L- and D-PIA was about 60 fold. The purine transport inhibitor dipyridamole potentiated the inhibitory effect of adenosine but not that of its analogues. The inhibitory responses evoked by adenosine and its' analogues were attenuated by the adenosine antagonist theophylline. These results indicate that adenosine selectively inhibits contractions of the rabbit portal vein evoked by adrenergic nerve stimulation via activation of an adenosine A1 receptor.

Inherent bias and noise in the hough transform

Considering the Hough transformation as a linear imaging process recasts certain well-known problems, provides a useful vocab-ulary, and possibly indicates a source of applicable literature on the behavior of the Hough transformation in various forms of noise. A consideration of the analytic form of peaks in parameter space sets the stage for the idea of using complementary (negative) votes to cancel off-peak positive votes in parameter space, thus sharpening peaks and reducing bias.

Multiple congenital heart anomalies in five Arabian foals

Five Arabian or half-Arabian foals with suspected multiple cardiac anomalies were examined. Various combinations of clinical examination, electrocardiography, angiocardiography, cardiac catheterization, blood gas analysis, radiography, and echocardiography resulted in clinical data that allowed accurate antemortem diagnoses to be made. In 4 cases, the clinical diagnosis was substantiated by postmortem findings. The confirmed diagnoses were: pseudotruncus arteriosus, a combination of patent ductus arteriosus, pulmonic stenosis, and tricuspid stenosis, pentalogy of Fallot, and tricuspid atresia. The surviving horse was believed to have an interventricular septal defect and patent ductus arteriosus, or a persistent truncus arteriosus.

Evidence for an A2/Ra adenosine receptor in the guinea-pig trachea

1 An attempt was made to determine whether the extracellular adenosine receptor that mediates relaxation in the guinea-pig trachea is of the A(1)/R(i) or A(2)/R(a) subtype.2 Dose-response curves to adenosine and a number of 5'- and N(6)-substituted analogues were constructed for the isolated guinea-pig trachea, contracted with carbachol.3 The 5'-substituted analogues of adenosine were the most potent compounds tested, the order of potency being 5'-N-cyclopropylcarboxamide adenosine (NCPCA) > 5'-N-ethylcarboxamide adenosine (NECA) > 2-chloroadenosine > L-N(6)-phenylisopropyladenosine (L-PIA) > adenosine > D-N(6)-phenylisopropyladenosine (D-PIA).4 The difference in potency between the stereoisomers D- and L-PIA on the isolated trachea was at the most five fold.5 Responses to low doses of adenosine and its analogues were attenuated after treatment with either theophylline or 8-phenyltheophylline. The responses to 2-chloroadenosine were affected to a lesser extent than were those to the other purines.6 Adenosine transport inhibitors, dipyridamole and dilazep, potentiated responses to adenosine, did not affect those to NCPCA, NECA, L-PIA and D-PIA but significantly reduced the responses to high doses of 2-chloroadenosine.7 Relaxations evoked by 9-beta-D-xylofuranosyladenosine which can activate intracellular but not extracellular adenosine receptors, were attenuated by dipyridamole but unaffected by 8-phenyltheophylline.8 The results support the existence of an extracellular A(2)/R(a) subtype of adenosine receptor and an intracellular purine-sensitive site, both of which mediate relaxation.

Surface-associated growth

In natural ecosystems, microbial activity is often associated with the presence of a surface, particularly in low-nutrient environments. The chemostat allows the study of such low-nutrient environments together with the precise control of other growth parameters. By using this system, enrichment cultures with inocula from two different river sources have been made. A more diverse community attached itself to surfaces placed in the chemostat when the cultures were carbon-limited than when the limiting nutrient was nitrogen. Further studies on a pseudomonad isolated from the carbon-limited enrichment cultures have shown that surface-associated organisms grow at approximately twice the rate of the same organism in the free surrounding medium. A hypothesis to explain this phenomenon based on the chemiosmotic theory is discussed.

Adenosine contracts the isolated rat tail artery by releasing endogenous 5-hydroxytryptamine

Adenosine (10(-4)-10(-3) M) contracted the isolated rat tail artery. This effect exhibited rapidly developing tachyphylaxis. Methysergide (10(-7) M) prevented the contractile response to adenosine and 5-hydroxytryptamine (5-HT) without affecting that to noradrenaline. Pretreatment of rats with parachlorophenylalanine (PCPA) abolished the contraction to adenosine (5 X 10(-4) M). Responses to 5-HT and noradrenaline were not significantly affected. These results indicate that the contractile response of the rat tail artery induced by adenosine is probably mediated by endogenous 5-HT.

Evidence in support of the P1/P2 purinoceptor hypothesis in the guinea-pig taenia coli

1 The relaxations induced by adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), adenosine 5'-monophosphate (AMP) and adenosine on the carbachol-contracted taenia coli of the guinea-pig have been studied. ATP and ADP produce similar responses which differ in nature and time course from those of AMP and adenosine. 2 Theophylline, at concentrations (25-200 muM) lower than those which produce significant phosphodiesterase inhibition, blocks the effects of AMP and adenosine but fails to antagonize the responses elicited by ATP and ADP. The antagonism of adenosine by theophylline appears to be competitive. 3 Apamin (1-100 nM) blocks the inhibitory effects of ATP and ADP but fails to antagonize the responses to AMP and adenosine. The antagonism by apamin is non-competitive. 4 The results indicate that ATP and adenosine relax the taenia coli by activating different receptors and are consistent with the P1, P2 purinoceptor hypothesis.

Spliced and unspliced RNAs encoded by virion RNA segment 7 of influenza virus

Cells infected with the avian influenza virus fowl plague virus, contains three species of polyadenylated RNA which are complementary to virion RNA segment 7. The largest is virtually a complete transcript of vRNA 7, and is the messenger RNA for the matrix protein, but the coding function of the two smaller species, which are approximately 320 and 285 nucleotides long (excluding poly(A)), is unknown. It is likely however that at least one of the small RNAs encodes a new virus polypeptide which has been predicted from the nucleotides sequence of vRNA 7. The major part of each RNA maps within about 300 nucleotides from the 5'-terminus of vRNA 7, but the larger species also contains additional sequences derived from the 3' terminus. Production of the two small RNAs may involve alternative patterns of splicing of the matrix protein mRNA.

Some mathematical and representational aspects of solid modeling

An approach is presented to the tripartite problem of modeling physical solids mathematically, representing the models in a computer, and using representations in geometric algorithms. Examples are primarily from the domain of manufacturing and design of discrete goods, but the results reported here have wider significance. Mathematical definitions can formalize many of our intuitions about three-dimensional (3-D) objects and operations on them. Representation-free (mathematical) models and functions allow formal properties to be defined for characterizing geometric representations. Three common representation schemes for 3-D objects are described briefly, along with some of their formal and informal properties. A rigorous, as opposed to ad hoc, approach to modeling has several advantages. Broadly, the conceptual complications and ambiguities which are endemic to ad hoc problem statements and solutions may be avoided by appealing to a precise mathematical semantics. Mathematical rigor is mandatory in applications such as automatic manufacturing in which correctness must be guaranteed and consistency and validity maintained.

The structural conformation of the polyphosphate chain of the ATP molecule is critical for its promotion of prostaglandin biosynthesis

The adenine nucleotide ATP relaxed the tracheal strip of the guinea pig, while the methylene isosteres of ATP, alpha, beta-methylene ATP (APCPP) and beta, gamma-methylene ATP (APPCP) in concentrations up to 100 micrograms were either inactive or produced a small contraction. The relaxation of the tracheal strip elicited by ATP was completely abolished by treatment of the tissue with indomethacin, a prostaglandin synthesis inhibitor. The relaxations induced by ATP in the guinea-pig taenia coli were followed by a rebound contraction which could be blocked by indomethacin. The two methylene analogues of ATP, produced relaxations in the taenia coli which were not followed by a rebound contraction. It is concluded that in the guinea-pig tracheal chain and taenia coli preparations ATP stimulated prostaglandin synthesis while the analogues modified in the polyphosphate chain were unable to do so.

Need for high resolution in VUV Rydberg state spectroscopy

The necessity for high energy resolution (resolving powers > 100,000) in VUV spectroscopic determinations of atomic and molecular Rydberg electronic structures is emphasized. Examples include spectral observations of Rydberg levels in Ge I near the 4p(2)P( degrees )((1/2)) limit, in Sr I near the 4d(2)D(3/2) limit, and in the diatomic hydrogen halides (especially HI) below the X(2)II(3/2) limit.

Clinical, anatomic and functional descriptors influencing morbidity, survival and adequacy of revascularization following coronary bypass

Clinical data on 3,479 consecutive patients having coronary bypass surgery were retrospectively analyzed. Perioperative complications, incomplete revascularization, and reduced long-term survival could frequently be correlated with manifestations of myocardial damage. Patients with triple vessel and left main coronary disease had a greater frequency of inotropic requirements than did patients with single or double vessel disease (7.9% and 8.6% vs. 3.8% and 4.2%). Inotropic requirements in the perioperative period were significantly increased for patients with preoperative left ventricular dysfunction; a history of heart failure or multiple infarctions did not significantly increase the incidence of inotropic requirements. Presence of previous myocardial infarction, heart failure, or left ventricular contraction abnormalities significantly decreased the ability to achieve complete revascularization with bypass grafting. Hospital mortality since 1976 has been 0.8% (25/3,040). Hospital mortality was significantly increased by history of myocardial infarction, hypertension, heart failure, extent of anatomic disease, presence of preoperative ST-T wave changes, and severe abnormalities of left ventricular function. Hospital mortality in patients with ejection fraction </=0.35 was 3.4% vs. 1.3% for those >0.35. Anginal pattern, history of hypertension, previous myocardial infarction, preoperative heart failure all significantly affected long-term survival. Occurrence of perioperative myocardial infarction did not adversely influence long-term survival. Patients with normal left ventricular function had excellent 42 month survival regardless of vessel disease (95%, 96%, and 94% for single, double, and triple vessel disease, respectively). Survival was significantly less for such patients with abnormal left ventricular function. Inability to achieve complete revascularization did not adversely affect hospital mortality, but did significantly reduce late survival. The important effect which complete revascularization had on long-term survival appeared to increase with increasing severity of coronary disease. Although bypass grafting improves survival in patients with multivessel disease and left ventricular dysfunction, the benefits appear to be significantly reduced once manifestations of left ventricular damage have occurred.

Relationship between the messenger RNAs transcribed from two overlapping genes of influenza virus

The relationship of the mRNAs encoding the NS1 and NS2 polypeptides of influenza virus has been investigated through synthesis and characterisation of complementary DNA copies of the mRNAs. Previous work had shown that both mRNAs are encoded by virion RNA segment 8, and that the sequences comprising the smaller of the two mRNAs (the NS2 mRNA) were also present on the NS1 mRNA. Our results indicate that the mRNA encoding the NS2 polypeptide of the avian influenza, fowl plague virus, is approximately 400 ntds long, and that its sequences correspond largely with the 3'-terminal region of the NS1 mRNA.

Myoblastoma. Equine granular cell tumor

A unilateral pulmonary granular cell tumor occurred in a Thoroughbred mare with longstanding respiratory disease wrongly attributed to chronic obstructive pulmonary disease. The clinical features, radiology and endoscopic appearance permitted an accurate diagnosis, which was supported by subsequent necropsy and histologic examination. Obstructive pulmonary disease was ruled out after measurement of arterial blood gases and maximum intrathoracic pressure changes, and after microscopic examination of the lung.

Physiological basis for meso-tartrate sensitivity in some strains of Salmonella typhimurium

meso-Tartrate inhibited the growth of non-meso-tartrate-utilizing strains of Salmonella typhimurium in peptone water media and mineral salts media with some, but not all, carbon sources. C-R intermediates of the tricarboxylic acid cycle or compounds readily converted to them and substrates metabolized independently of the C-6 part of the cycle spared bacteria from the inhibitory effects of meso-tartrate when added to cultures along with meso-tartrate. Experiments with cell-free extracts of non-meso-tartrate-utilizing strains from batch and continuous cultures showed that meso-tartrate was a competitive inhibitor of isocitrate dehydrogenase and isocitrate lyase activities and also inhibited citrate synthase and malate synthase activities. The synthesis of these enzymes was not inhibited by meso-tartrate. The isocitrate enzymes of meso-tartrate-utilizing strains of S. typhimurium were similarly inhibited by meso-tartrate, but inhibition of the growth of meso-tartrate-utilizing strains was demonstrable only in uninduced cultures in which the intracellular concentrations of meso-tartrate were high.

Assessment of myocardial function in the horse. 1. Theoretical and technical considerations

The paper discusses the various parameters which are currently used in attempts to assess the contractile efficiency of the myocardium in various species. These procedures depend upon accurate recording of intracavity pressure. The response of a catheter-mounted microtransducer compared with a fluid-filled catheter manometer system is illustrated to show the advantage of the former in providing a true representation of pressure changes.

Assessment of myocardial function in the horse. 2. Experimental findings in resting horses

The paper describes observations on 8 horses at rest using catheter-mounted microtransducers to record intracavity pressures. In 5 of them records were obtained from both left and right sides and in 3 horses from the right heart only. Twelve indices were measured. Variations in left ventricular end-diastolic pressure seemed to influence the results on many of the parameters. It is suggested that left ventricular end-diastolic pressure itself may be a useful guide to left ventricular functional efficiency but more work is necessary to further evaluate these indices as possible measures of myocardial function in the horse.

The smallest genome RNA segment of influenza virus contains two genes that may overlap

The genome of influenza virus consists of eight segments of single-stranded RNA, each of which encodes a different polypeptide. In addition to the eight recognized gene products, the virus specifies a distinct smaller nonstructural polypeptide (NS2), which is translated from a separate species of virus-specific mRNA. The location on the virus genome of the gene encoding this polypeptide was investigated by hybridization of the NS2 mRNA with isolated subgenomic RNA species, and by correlation of the inheritance of a strain-specific NS2 with inheritance of particular genome RNA segments during recombination between two different virus strains. The genetic information for NS2 was found to reside in the smallest genome RNA segment of the virion, which also encodes the NS1 polypeptide. Considering the sizes of the molecules involved, it is likely that the coding sequences for the two polypeptides overlap.

The effects of alpha-adrenoceptor agonists and antagonists on responses of transmurally stimulated prostatic and epididymal portions of the isolated vas deferens of the rat

1 The effects of alpha-adrenoceptor agonists and antagonists on contractile responses of transmurally stimulated prostatic and epididymal portions of the rat isolated vas deferens were examined. 2 Responses to single stimuli consisted of two phases, the first predominant in the prostatic and the second in the epididymal portion. The first phase was resistant to alpha-adrenoceptor antagonists but the second was reduced in a dose-related manner in the order of potency prazosin greater than azapetine greater than phentolamine greater than labetalol greater than yohimbine. 3 Both phases of the response to a single stimulus were reduced by clonidine but only the first could be reliably restored by yohimbine. 4 Trains of transmural stimuli produced biphasic responses, an early rapid component predominant in the prostatic and a slow secondary component predominant in the epididymal portion. The effects of alpha-adrenoceptor antagonists on these responses were complex. Prazosin produced the most straightforward inhibition of responses with relative resistance of the early rapid component. Only yohimbine and phentolamine produced increases in responses which could be pre-junctional in origin. 5 The alpha-adrenoceptor agonists, oxymetazoline and clonidine, reduced while phenylephrine increased responses to trains of stimuli. 6 These results are discussed in relation to the nature of the innervation of rat vas deferens and the usefulness of the preparation in pharmacological tests for activity at alpha-adrenoceptors.

Phonocardiography in the horse: 2. The relationship of the external phonocardiogram to intracardiac pressure and sound

The paper describes observations during individual cardiac cycles on the changing pressures and sounds recorded from the various chambers of the heart and aorta, related to phonocardiograms from an external microphone hand-held over the cardiac area. The majority of the first sound appears to arise from the left side of the heart after the AV valves have closed and the second sound is a consequence of sudden deceleration of blood against already closed semilunar valves. Systolic murmurs at the aortic root may be benign from increased flow and turbulence at the peak of ejection but these may not be recorded externally.

Influence of oxygen tension on nitrate reduction by a Klebsiella sp. growing in chemostat culture

At dissolved oxygen tensions of 15 mmHg (2 kPa) and below, nitrate-limited continuous cultures of Klebsiella K312 synthesized nitrate reductase (NR) and nitrite reductase (NiR) and excreted ammonia. Under anaerobic conditions over 60% of the nitrate-nitrogen utilized was excreted as ammonia. In contrast, carbon-limited cultures excreted nitrite at dissolved oxygen tensions of 15 mmHg or below and synthesized NR but not NiR. Ammonia repressed neither NR nor NiR synthesis. These observations indicate that below a critical oxygen tension of 15 mmHg Klebsiella K312 utilizes oxygen and nitrate as electron acceptors. This oxygen tension correlates well with the critical oxygen tension observed for a change from oxidative to fermentative metabolism in cultures of Klebsiella aerogenes. The product of dissimilatory nitrate reduction is ammonia in nitrate-limited cultures but principally nitrite in carbon-limited (nitrate excess) cultures.