Virulence of Streptococcus suis type 2 strains in newborn germfree pigs depends on phenotype

To determine whether the virulence of Streptococcus suis type 2 is associated with the phenotype of the strain, we infected newborn germfree pigs with 10 strains of S. suis type 2 categorized by three phenotypes. In an earlier study, the phenotypes were distinguished by the presence or absence of the muramidase-released protein (MRP) and an extracellular factor (EF) and were designated MRP+ EF+, MRP+ EF- and MRP- EF-. Pigs were first inoculated with Bordetella bronchiseptica to predispose them to infection and were then intranasally inoculated with the streptococci. Strains of the MRP+ EF+ phenotype induced fever and increased the number of polymorphonuclear leukocytes in blood. Specific clinical signs of disease such as nervous disorders and lameness were also observed. At necropsy bacteriologic and pathologic examination disclosed meningoencephalitis, polyserositis, and polyarthritis. Strains of the MRP+ EF- phenotype induced only nonspecific clinical signs of disease such as recumbency, lack of appetite, and fever; only slight pathologic changes were detected in the serosae. The four strains of the MRP- EF- phenotype induced no signs of disease. These findings indicate that the 110-kDa EF and, to a lesser degree, the 136-kDa MRP may be associated with the virulence of the bacterium. The results demonstrated that S. suis type 2 strains producing both MRP and EF are pathogenic for pigs.

Cytolysins of Actinobacillus pleuropneumoniae serotype 9

Cytolysin I (ClyI) and cytolysin II (ClyII), which are present in the culture supernatant of Actinobacillus pleuropneumoniae serotype 9, are thought to play an important role in the pathogenesis of pig pleuropneumonia. The purpose of this study was to clone and characterize the genetic determinants of these cytolysins. Cloning was accomplished by the screening of DNA libraries for the presence of cytolytic activity and for the presence of DNA sequences homologous to leukotoxin DNA of Pasteurella haemolytica. Both genetic determinants were found to be members of the RTX cytotoxin family. The ClyII determinant was characterized in more detail. It appeared that ClyII more closely resembled the leukotoxin of P. haemolytica than the alpha-hemolysin of Escherichia coli. The ClyII amino acid sequence was identical to a hemolysin gene sequence of A. pleuropneumoniae serotype 5; this finding indicates that the latter gene also codes for ClyII and not for ClyI, as has previously been suggested. The genetic organization of the ClyII determinant differed from the genetic organization of other RTX determinants. Genes responsible for secretion of ClyII were not contiguous with the toxin gene. Instead, secretion genes were present elsewhere in the genome. These secretion genes, however, belong to the ClyI operon. This indicates that the secretion genes of the ClyI operon are responsible for secretion of ClyI and ClyII.

Identification of two proteins associated with virulence of Streptococcus suis type 2

The protein profiles of various cell fractions of 180 strains of Streptococcus suis type 2, which were isolated from diseased pigs, from healthy pigs when they were slaughtered, and from human patients, were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The isolates from diseased pigs contained two proteins that were absent in most of the isolates from healthy pigs. One of these proteins was a 136-kDa protein that was previously identified as the muramidase-released protein (MRP). This protein was predominantly detected in protoplast supernatants and culture supernatants. The second protein was a 110-kDa protein that was detected only in culture supernatants and therefore was provisionally called extracellular factor (EF). Three phenotypes of S. suis type 2 strains were recognized. Isolates from organs of diseased pigs mainly belonged to the MRP+ EF+ phenotype (77%), while isolates from tonsils of healthy pigs mainly had the MRP- EF- phenotype (86%). Most of the isolates from human patients contained MRP (89%); 74% had the MRP+ EF- phenotype. These findings confirm the results of previous investigations which demonstrated that S. suis type 2 strains differ in virulence. Monoclonal antibodies raised against the 110-kDa EF recognized proteins with higher molecular weights in culture supernatants of all of the strains with the MRP+ EF- phenotype. However, none of the strains with the MRP+ EF+ phenotype produced these high-molecular-weight proteins. Our results demonstrate that MRP and EF are associated with virulence. This suggests that one or both of these proteins are virulence factors that play a role in the pathogenesis of S. suis type 2 infections in pigs and human patients.

High affinity dopamine D2 receptor radioligands. 1. Regional rat brain distribution of iodinated benzamides

Five 125I-labeled substituted benzamides, which are close structural analogues of (S)-sulpiride, eticlopride, and isoremoxipride, were evaluated for their selective in vivo uptake into dopamine D2 receptor rich tissue of the rat brain. "Iodopride" (KD 0.88 nM), an iodine substituted benzamide structurally related to sulpiride, displayed a maximal striatum: cerebellar uptake ratio of 7.6. Demonstration of saturation of the receptor with [125I]iodopride in striatum required uptake in frontal cortex to be used, rather than cerebellar uptake, to define nonspecific binding. Two other ligands structurally related to eticlopride, "iclopride" (KD 0.23 nM) and "itopride" (KD 0.16 nM), displayed maximal striatal: cerebellar uptake ratios of 9.8 and 3.3, respectively. The most potent ligands, "epidepride" (KD 0.057 nM) and "ioxipride" (KD 0.070 nM) showed striatal:cerebellar uptake ratios of 234 and 65, respectively. The observed uptake ratios correlated poorly with the affinity constants for the dopamine D2 receptor alone, but were highly correlated (r = 0.92) with the product of the receptor dissociation constant (KD) and the apparent lipophilicity (kw), as determined by reverse-phase HPLC at pH 7.5. Total striatal uptake also appeared dependent on lipophilicity, with maximal uptake occurring for ligands having log kw 2.4-2.8.

Role of IME1 expression in regulation of meiosis in Saccharomyces cerevisiae

Two signals are required for meiosis and spore formation in the yeast Saccharomyces cerevisiae: starvation and the MAT products a1 and alpha 2, which determine the a/alpha cell type. These signals lead to increased expression of the IME1 (inducer of meiosis) gene, which is required for sporulation and sporulation-specific gene expression. We report here the sequence of the IME1 gene and the consequences of IME1 expression from the GAL1 promoter. The deduced IME1 product is a 360-amino-acid protein with a tyrosine-rich C-terminal region. Expression of PGAL1-IME1 in vegetative a/alpha cells led to moderate accumulation of four early sporulation-specific transcripts (IME2, SPO11, SPO13, and HOP1); the transcripts accumulated 3- to 10-fold more after starvation. Two sporulation-specific transcripts normally expressed later (SPS1 and SPS2) did not accumulate until PGAL1-IME1 strains were starved, and the intact IME1 gene was not activated by PGAL1-IME1 expression. In a or alpha cells, which lack alpha 2 or a1, expression of PGAL1-IME1 led to the same pattern of IME2 and SPO13 expression as in a/alpha cells, as measured with ime2::lacZ and spo13::lacZ fusions. Thus, in wild-type strains, the increased expression of IME1 in starved a/alpha cells can account entirely for cell type control, but only partially for nutritional control, of early sporulation-specific gene expression. PGAL1-IME1 expression did not cause growing cells to sporulate but permitted efficient sporulation of amino acid-limited cells, which otherwise sporulated poorly. We suggest that IME1 acts primarily as a positive regulator of early sporulation-specific genes and that growth arrest is an independent prerequisite for execution of the sporulation program.

The incidence of liability claims in ophthalmology as compared with other specialties

Ophthalmologists continue to share in the professional liability claims that plague the medical profession. Data have been extrapolated from the April 1987 publication of the United States General Accounting Office (GAO) entitled, "Medical Malpractice Characteristics of Claims Closed in 1984." This document presents information pertaining to the comparative incidence of professional liability claims of ophthalmologists with other specialties.

Positive control of sporulation-specific genes by the IME1 and IME2 products in Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, meiosis and spore formation require the induction of sporulation-specific genes. Two genes are thought to activate the sporulation program: IME1 and IME2 (inducer of meiosis). Both genes are induced upon entry into meiosis, and IME1 is required for IME2 expression. We report here that IME1 is essential for expression of four sporulation-specific genes. In contrast, IME2 is not absolutely essential for expression of the sporulation-specific genes, but contributes to their rapid induction. Expression of IME2 from a heterologous promoter permits the expression of these sporulation-specific genes, meiotic recombination, and spore formation in the absence of IME1. We propose that the IME1 and IME2 products can each activate sporulation-specific genes independently. In addition, the IME1 product stimulates sporulation-specific gene expression indirectly through activation of IME2 expression.

Chloro-substituted, sterically hindered 5,11-dicarbo analogues of clozapine as potential chiral antipsychotic agents

Variable-temperature proton nuclear magnetic resonance studies have shown that 5-(2-propylidene)-10-(4-methylpiperazino)-5H-dibenzo[a,d] cycloheptene, a 5,11-dicarbo analogue of the atypical neuroleptic agent clozapine [8-chloro-11-(4-methylpiperazino)-5H-dibenzo[b,e][1,4]diazepine], exists as thermally stable configurational isomers. The presence of the 2-propylidene group at C-5 on the 5H-dibenzo[a,d]cycloheptene moiety did not interfere greatly, as compared to clozapine, with the in vitro affinity of this 5,11-dicarbo analogue of clozapine for muscarinic and dopamine D-1 and D-2 binding sites in rat brain. Since the presence and position of a chloro substituent on the 5H-dibenzo[b,e][1,4]diazepine moiety have a marked influence on the respective binding affinities of 1,4-diazepines related to clozapine, chloro-substituted 5,11-dicarbo analogues of clozapine were prepared in order to further examine structure-activity relationships. Evaluation of these analogues for binding to muscarinic and dopamine binding sites in comparison with clozapine and other 5H-dibenzo[b,e][1,4]diazepine analogues of clozapine shows that the dopamine D-1 and D-2 receptor affinities of both the 5-(2-propylidene)-5,11-dicarbo analogue and its corresponding distal-chloro derivative, 2-chloro-5-(2-propylidene)-10-(4-methylpiperazino)-5H- dibenzo[a,d]cycloheptene, are retained. Because of the susceptibility to acid-catalyzed hydrolysis of these tertiary enamines, however, these compounds serve only as model compounds for their structure-activity evaluation. Since the proximal nitrogen atom of the piperazine ring is redundant for biological activity, 5-(2-propylidene)-10-(1-methyl-4-pyridyl)-5H-dibenzo[a,d]cycloh eptene and its 2-chloro derivative are excellent candidates for resolution into enantiomers as a means to separate antimuscarinic and antidopaminergic activity, respectively, associated with only a single stereoisomer.

Sterically hindered 5,11-dicarbo analogues of clozapine as potential chiral antipsychotic agents

Sterically hindered 5,11-dicarbo analogues of clozapine were prepared as potential chiral antipsychotic agents, with the possibility that for a particular analogue the antipsychotic activity of clozapine may reside in one enantiomer of the analogue whereas other unwanted biological effects of clozapine may be caused by the other enantiomer. Variable-temperature proton nuclear magnetic resonance studies showed that although 5-methylene-10-(4-methylpiperazino)-5H-dibenzo[a,d]cycloheptene exists at room temperature as configurational enantiomers, the activation energy for thermal racemization is 19 kcal mol-1 at 105 degrees C, and it is doubtful that the enantiomers of this analogue can be isolated under usual laboratory conditions. The (Z)-5-ethylidene and 5-isopropylidene analogues have activation energies greater than 23 kcal mol-1 at 160 degrees C, and thus there is a possibility that the analogues can be obtained as their respective enantiomers. 5-Methyl-10-(4-methylpiperazino)-5H-dibenzo[a,d]cycloheptene incorporates a chiral center which is not thermally racemized, but it exists at room temperature as two diasteromers with an activation energy for inversion of the 5H-dibenzo[a,d]cycloheptene ring of 21 kcal mol-1. When the 5,11-dicarbo analogues were tested in vitro for biological activity and their activities were compared to that of clozapine, the affinities for muscarinic and dopamine D-1 and D-2 sites were reduced but were still substantial. Thus the respective biological activities of the racemates indicate that the biological activities of the thermally stable enantiomers may be of importance in finding a clozapine derivative with fewer side effects than those shown by clozapine itself. Because of the susceptibility of the enamines to acid-catalyzed hydrolysis, resolution into respective enantiomers is not anticipated.

A transcriptional cascade governs entry into meiosis in Saccharomyces cerevisiae

Two signals activate meiosis in yeast: starvation and expression of the a1 and alpha 2 products of the mating-type locus. Prior studies suggest that these signals stimulate expression of an activator of meiosis, the IME1 (inducer of meiosis) product. We have cloned a gene, IME2, with properties similar to those of IME1: both genes are required for meiosis, and both RNAs are induced in meiotic cells. Elevated dosage of IME1 or IME2 stimulates the meiotic recombination pathway without starvation; thus, the IME products may be part of the switch that activates meiosis. IME1 was found to be required for IME2 expression, and a multicopy IME2 plasmid permitted meiosis in an ime1 deletion mutant. Accordingly, we propose that the IME1 product stimulates meiosis mainly through activation of IME2 expression.

(S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5-[125I]iodo- 2-methoxybenzamide hydrochloride, a new selective radioligand for dopamine D-2 receptors

From salicyclic acid, the two enantiomers of N-[(1-ethyl-2-pyrrolidinyl)methyl]-5-iodo-2-methoxybenzamide (6b) were prepared in a five-step synthesis. With use of Heindel's triazene method for introduction of the radionuclide, the iodine-125-labeled substituted benzamide was obtained with a calculated specific activity of 136 Ci/mmol and 14% radiochemical yield. For the preparation of the iodine-125-labeled benzamide with higher specific activity, this method was unsuccessful and utilization of the corresponding tri-n-butyltin derivative was required. Treatment of the latter in dilute hydrochloric acid with sodium iodide-125 and chloramine-T gave [125I](S)-6b in 56% radiochemical yield and at least 97% radiochemical purity. The displacement of [125I](S)-6b and [3H](S)-sulpiride from their respective binding sites in striatal rat brain homogenates using various neuroleptic agents showed that (S)-6b has the same binding profile but more potent binding for dopamine D-2 receptors than has sulpiride. These experiments also indicate that the S enantiomer of 6b is a specific ligand (KD = 1.2 nM) for the D-2 receptor. Further, the octanol-water partition coefficient of (S)-6b as determined by reverse-phase high-performance liquid chromatography was found to be 40 times greater than that for sulpiride. Thus (S)-6b has a lipophilicity that will allow a relatively higher uptake into the brain compared to sulpiride. In vivo experiments with rats show that [125I](S)-6b penetrates readily into the brain and is preferentially localized in the striatum as compared to the cerebellum, the ratio of uptake being 7.2 to 1, 60 min after injection. These observations of good brain penetration and high affinity and selectivity for D-2 receptors indicate that the corresponding iodine-123-labeled benzamide may be a useful ligand for the noninvasive visualization study of dopamine D-2 receptor sites in vivo by single photon emission computed tomography.

A further indigenous case of 'North American' blastomycosis from South Africa. Importance of skin lesions in early diagnosis

A case of disseminated blastomycosis is reported. The patient presented with lung involvement, lupus vulgaris-like lesions, mainly of the face, and subcutaneous abscesses overlying areas of bone destruction. The diagnosis was confirmed by mycological microscopy and culture of skin material from involved areas. The importance of early diagnosis and the favourable response to treatment are emphasized.

Cutaneous flavobacteriosis--polymorphous skin granulomas from Flavobacterium capsulatum. A case report

A case of multiple eruptive skin granulomas caused by Flavobacterium capsulatum is described. The organism was resistant or poorly sensitive to all antibiotics except carbenicillin. Cure was brought about by using maximal doses of this drug. The source of the infection could not be proved, but it dated from an orthopaedic procedure to the elbow which was followed by a chronic cellulitis at the operation site. Since this is an organism known to occur in stored water, it was presumed that the flavobacterium was introduced into the wound from bottles of boiled and cooled water used in the operating theatre.

Affinity of 10-(4-methylpiperazino)dibenz[b,f]oxepins for clozapine and spiroperidol binding sites in rat brain

10-(4-Methylpiperazino)dibenz[b,f]oxepins were prepared and evaluated as potential antipsychotic agents using specific clozapine [8-chloro-11-(4-methylpiperazino)-5H-dibenzo[b,e][1,4]diazepine] binding sites in rat forebrain that are noncholinergic and nondopaminergic in nature and from which [3H]clozapine is displaced by known antipsychotic agents. [3H]Clozapine binding in the presence of atropine represents nonmuscarinic binding, while binding in the absence of atropine represents muscarinic (cholinergic) plus nonmuscarinic binding. The relative affinity for dopamine binding sites was determined by displacement of [3H]spiroperidol from binding sites in rat caudate nuclei. Thus, clozapine, its 2-chloro isomer, its dechloro analogue, and their 5H-dibenzo[a,d]cycloheptene and dibenz[b,f]oxepine analogues have about the same relative affinity for the nonmuscarinic clozapine binding sites. At the spiroperidol (dopaminergic) sites, both the nature of the tricyclic system and the presence of a chlorine atom on the tricyclic system have a substantial effect on the binding affinity. Within each series, shift or a chlorine atom from the position distal to the piperazino group to the proximal position increases the binding affinity by a factor of about nine, but removal of the chlorine atom substantially decreases the binding affinity. Nevertheless, 10-(4-methylpiperazino)dibenz[b,f]oxepin has a threefold greater affinity for the dopaminergic binding sites than does clozapine itself.

Differential competition by L-alpha-methyldopa metabolites for adrenergic receptors in rat forebrain

The capacity of a series of intraneuronal metabolites of L-alpha-methyldopa to compete for alpha-1 ([3H]prazosin, alpha-2([3H]clonidine and beta ([3H]dihydroalprenolol) receptor binding in rat forebrain was studied. Each metabolite studied had a unique order of activity at each receptor. These data show that (-)-erythro-alpha-methylnorepinephrine and (-)-erythro-alpha-methylepinephrine compete with high affinity for alpha-2 receptors, thereby supporting the suggestion that alpha-2 receptors mediate hypotensive effects of L-alpha-methyldopa . Furthermore, these metabolites of L-alpha-methyldopa competed with high potency for beta-1 receptors in forebrain and (-)-erythro-alpha-methylepinephrine was more potent than (-)-epinephrine, (-)-norepinephrine and (-)-erythro-alpha-methylnorepinephrine in competing for beta-2 receptors on human lymphocytes. These data suggest that beta receptor stimulation may be important in determining the net effects of L-alpha-methyldopa. L-alpha-Methyldopa metabolites were much less potent than (-)-epinephrine and (-)-norepinephrine in competition for alpha-1 receptors. (+/-)-alpha-Methyldopamine was less potent than other l-alpha-methyldopa metabolites at all three receptors, suggesting that it is unlikely to be an important hypotensive metabolite of L-alpha-methyldopa.

Doctors and society: a Northern Thailand study

This paper presents findings from a survey together with other observations to characterize the medical profession in Northern Thailand. Data were obtained in early 1976 using a self-administered questionnaire which was completed by 132 physicians in three Northern Thai provinces. Officially approved Thai medicine is 'Western' in nature and is predominantly an urban phenomenon. Practitioners of indigenous medicine are widespread and although illegal, they are tolerated. Training of doctors conforms very largely to Western standards. This plus the limited demand for private medical care results in a high proportion of the graduates of Thai medical schools migrating abroad. Results of the survey indicate that doctors in Northern Thailand were predominantly government employees or staff of a private hospital. Less than 5% were solely in self-employment. However, most 'employee' doctors had a private 'after hours' practice. Two types of medical professionals were identified: the 'cosmopolitan' and the 'local' doctor. Difficulties in communicating with patients were indicated by about 30% of the respondent doctors. The level of dissatisfaction expressed by the doctors surveyed was relatively high--43%. Items most often mentioned were: over-work, low compensation and lack of cooperation of patients. Satisfaction most often mentioned were: service to others, independent occupation and prestige with which doctors are regarded. In the analysis, the influence of several independent variables on type of professionalism and on satisfaction-dissatisfaction was determined.

(alpha S)-erythro-alpha-methylepinephrine: preparation and stereoselective binding to adrenergic receptors in rat forebrain

The enantiomers of a number of catecholamines, including (alpha S)- and (alpha R)-erythro-alpha-methylepinephrine, were evaluated for their capacity to compete for binding sites in rat forebrain homogenates with [3H]prazosin, a ligand which selectively binds to adrenergic receptors of the alpha 1 subtype. (alpha R)-erythro-alpha-Methylepinephrine is devoid of apparent biological activity, but the activity of the alpha S isomer is substantial. The latter is less active than the endogeneous catecholamines, (R)-norepinephrine and (R)-epinephrine, but the stereospecific competition for [3H]prazosin binding sites by the catecholamine isomers with the beta R configuration is additional evidence that (alpha S)-erythro-alpha-methylepinephrine may be a biologically active metabolite of L-alpha-methyl-3,4-dihydroxyphenylalanine.

Synthesis of clozapine analogues and their affinity for clozapine and spiroperidol binding sites in rat brain

Analogues of clozapine, some prepared by a novel, shorter synthesis than those described previously, were evaluated as potential antipsychotic agents using clozapine binding sites in rat forebrain that are nonmuscarinic and nondopaminergic in nature and from which [3H]clozapine is displaced by known antipsychotic agents. The binding of clozapine to muscarinic sites is inhibited in the presence of atropine. Displacement of [3H]clozapine by an analogue of clozapine in the presence of atropine represents nonmuscarinic binding, while displacement in the absence of atropine represents muscarinic (cholinergic) plus nonmuscarinic binding. The relative affinity of the analogues for dopamine binding sites was determined by their ability to displace [3H]spiroperidol from binding sites in rat caudate nuclei. To the extent which binding affinity for nonmuscarinic clozapine sites in rat forebrain reflects the antipsychotic potential of a particular drug, dibenzo-5H-cycloheptene analogues of clozapine are as effective as clozapine itself. Strong binding to nonmuscarinic clozapine sites is not dependent on the presence of a chlorine atom on th tricyclic system. One or both of the nitrogen atoms in the dibenzo-5H-[1,4]diazepine ring of clozapine appear to be necessary for the strong inhibition of clozapine binding to spiroperidol sites in rat caudate nuclei. Anticholinergic activity is substantially higher for clozapine and its dibenz[1,4]oxazepine analogue than for its benzo-5H-cycloheptene analogue.

Peroxisome-associated aldehyde dehydrogenase in normal rat liver

We have combined subcellular fractionation and cytochemical staining techniques to study the distribution of aldehyde dehydrogenase in rat liver. In addition to confirming the mitochondrial and microsomal localization of aldehyde dehydrogenase, this combined approach has allowed us to demonstrate that peroxisome-like organelles possess significant aldehyde dehydrogenase. When peroxisomal fractions are cytochemically stained for aldehyde dehydrogenase, activity is observed along membranes of structures resembling peroxisomal ghosts. These bodies lack a matrix but many appear to enclose peroxisomal cores. Moderate to dense reaction product is also located in single membrane-limited structures present in fractions containing morphologically recognizable peroxisomes. On occasion, the osmiophilic precipitate is also present in the matrix of intact peroxisomes. The aldehyde dehydrogenase activity in these peroxisome-like organelles prefers aliphatic aldehydes, including acetaldehyde in both millimolar and micromolar concentrations, and NAD. Aromatic aldehydes and NADP are also metabolized, but to a lesser extent. These results indicate that peroxisome-like organelles contain an aldehyde dehydrogenase activity possessing properties compatible with a role in ethanol metabolism.

Photoaffinity labeling of rat androgen binding protein

The photoinactivation and photoaffinity labeling of androgen binding sites present in cytosol prepared from intact sexually mature rat epididymides have been demonstrated by using unlabeled and [3H]-labeled 17 beta-hydroxy-4,6-androstadien-3-one. Both photoinactivation and photolabeling are dependent upon exposure to light. These processes are inhibited when photolysis is conducted in the presence of the photoinert compound 17 beta-hydroxy-5 alpha-androstan-3-one, suggesting that steroid-specific sites are involved in the reactions. The labeled steroid-specific product of photolysis is macromolecular with a molecular weight of 47,000 as determined by electrophoresis on polyacrylamide gels containing NaDodSO4, and proteinaceous because digestion of the cytosol with pronase before photolysis eliminates steroid-specific binding. After photolysis, the protein-steroid complex has the ability to withstand dissociation during electrophoresis under denaturing conditions, and unlabeled 17 beta-hydroxy-5 alpha-androstan-3-one fails to displace the label from the complex. Thus, the binding of [3H]17 beta-hydroxy-4,6-androstadien-3-one to the cytosolic protein is covalent. This steroid-specific product is identified as an androgen binding protein of testicular origin by its comigration with native androgen binding protein on nondenaturing polyacrylamide gels and by its molecular weight which is within the range reported for androgen binding protein subunits.

Structural and steric requirements for beta-phenethylamines as agonists of the noradrenergic cyclic AMP generating system in the rat limbic forebrain

The present studies were undertaken to assess the structural and steric requirements for beta-phenethylamines as agonists of the noradrenergic cyclic AMP generating system in slices of the rat limbic forebrain. Significant agonist activity of beta-phenethylamines requires a beta-3,4-dihydroxyphenethylamine with a beta-hydroxyl group in the R configuration. Thus, dopamine did not stimulate the system at concentrations up to 10(-3) M. Moreover, beta-hydroxyphenethylamines without a 3,4-catechol group (octopamine, phenylephrine, p-hydroxynorephedrine, metaraminol and methoxamine) - though exerting alpha-agonist activity in peripheral tissues - lack agonist activity in this particular cyclic AMP generating system. The effects of (R)-norepinephrine and (R)-isoproterenol at maximal concentrations were not additive. The results lend further support to the view that the cyclic AMP generating system in slices of the limbic forebrain is part of a norepinephrine receptor coupled adenylate cyclase system with a subpopulation of receptors that are beta in nature.

Agonist effects of beta-phenethylamines on the noradrenergic cyclic adenosine 3',5'-monophosphate generating system in rat limbic forebrain. Stereoisomers of p-hydroxynorephedrine

Significant agonist activity for the specific noradrenergic cyclic adenosine 3',5'-monophosphate (cAMP) generating system in rat limbic forebrain requires a beta-3,4-dihydroxyphenethylamine with a beta-hydroxyl group in the R configuration. Thus, neither of the enantiomers of p-hydroxynorephedrine nor of p-hydroxynorpseudoephedrine mimics the agonist activity of (R)-norepinephrine. It has yet to be established whether or not one of the p-hydroxynorephedrines exhibits antagonist activity in this same system.

Possible formation and development of spirochaete attachment sites found on the surface of symbiotic polymastigote flagellates of the termite Reticulitermes flavipes

We propose that spirochaete attachment sites arise from peripheral protrusions which appear on the surface of polymastigote flagellates. These protrusions develop into bracket-shaped structures which then form the mature attachment site. Next the site becomes detached from the surface of the cell; this latter process may be facilitated by the fusion of vesicles located in the region immediately beneath the spirochaete attachment site. This theory could explain the variability in the number and distribution of attachment sites on the surface of the flagellates.

Correlation between brain levels and biochemical effects of the optical isomers of p-chloroamphetamine

The biochemical effects of d- and l-p-chloroamphetamine (PCA) were compared with the brain levels of the unchanged drug at various times after a single injection. Initially both isomers produced rapid and pronounced decreases in the whole brain levels of serotonin and 5-hydroxyindoleacetic acid, tryptophan hydroxylase activity and the synaptosomal uptake of 3-H-serotonin. At later times (e.g., 2 weeks), the effects of the d-isomer were much more pronounced than were those of the l-isomer. At intermediate times (2-4 days), a variable and dose-dependent recovery of synaptsomal uptake activity and tryptophan hydroxylase activity occurred after d-PCA. In both whole brain and forebrain, long-term reductions in these activities were found. However, in the midbrain, an area containing the cell bodies of serotonergic neurons, only a slight initial decrease in tryptophan hydroxylase activity occurred. The whole brain levels of the two isomers were equal from 4 to 96 hours after injection and declined exponentially in a single monophasic manner monophasic decine of the levels of PCA was found in forebrain and midbrain samples. Thus, the initial and long-term effects of PCA are apparently mediated by different mechanisms. The former is correlated with the brain levels of the unchanged drug; the latter is not. The lack of any indication of a biphasic decay curve after 10 half-lives and the intermediate recovery of serotonergic function do not support a reserpine-like mechanism for the long-term effects of PCA. Instead, a mechanism related to neurotoxicity is proposed.

Ampicillin and tetracycline in the treatment and prophylaxis of chronic bronchitis

Ampicillin and tetracycline, in doses of 2 g a day, were compared in the treatment of acute exacerbations of chronic bronchitis. Seventy-nine patients were followed for 3 to 29 months and were treated for 118 exacerbations. Clinical improvement occurred after 10 days of treatment with either drug in over 80% of the cases. Haemophilus influenzae and Diplococcus pneumoniae were eradicated from the sputum more than 60% of the time, but in general there was a poor correlation between bacteriological clearing and clinical response. The effect of chemoprophylaxis with ampicillin and tetracycline in doses of 1 g a day on the frequency of acute exacerbations of bronchitis was compared with that of a placebo. Seven hundred eighty prophylactic regimens, consisting of one capsule every 12 hr for 5 days beginning with the first sign of a cold, were prescribed for 76 patients. Irrespective of the regimen, an acute exacerbation of bronchitis was encountered at approximately 13% of the follow-up visits to the clinic.

ANALYSIS OF MICROTUBULE STRUCTURE IN EUGLENA GRANULATA

The microtubules associated with the pellicle, reservoir and locomotory flagellum of Euglena granulata were subjected to rotational analysis using the technique of Markham et al. The results indicate that the microtubules have 11-14 subunits when viewed in transverse section. Rotational analysis of the entire locomotory flagellum was also conducted to better demonstrate the nature of the arms extending from the peripheral microtubules.