Functional expression of glucose-dependent insulinotropic polypeptide receptors is coupled to differentiation in a human adipocyte model.

OBJECTIVE: To establish that human adipocytes express functional glucose-dependent insulinotropic peptide (GIP) receptors and in particular the regulation of GIP receptor (GIPR) expression in the context of the dynamic process of adipocyte differentiation. DESIGN: A combination of semiquantitative real-time PCR and measurement of GIP-stimulated cAMP accumulation was used to establish the expression and functional coupling of GIPRs during in vitro differentiation of human Simpson-Golabi-Behmel syndrome (SGBS) preadipocytes. RESULTS: Semiquantitative real-time PCR revealed that GIPR expression was substantially increased by day 4 of differentiation, reaching a maximum around 6-8 days (approximately 200-fold increase above undifferentiated cells, n=2). We also analysed the expression of the adipocyte fatty acid binding protein (FABP4) to relate GIPR expression to a molecular differentiation marker of adipogenesis. FABP4 expression was barely detectable in undifferentiated cells. However, following exposure to adipogenic medium, FABP4 expression gradually increased, with a maximal expression level around 10 days (approximately 1,600,000-fold increase above undifferentiated cells, n=2). Thus, the increases in GIPR mRNA during adipogenesis occur earlier than FABP4, suggesting that it might represent a gene expressed early in terminal differentiation and thus plays a role in fat droplet formation. A unit of 1 microM GIP failed to raise intracellular cAMP levels above basal levels in undifferentiated cells (n=3). In stark contrast, the 9-day differentiated cells produced a robust concentration-dependent increase in cAMP accumulation following stimulation with GIP, with an EC(50) value of 2.3 nM (n=3). The maximal response represented a 9-34-fold increase in cAMP accumulation above basal levels. CONCLUSIONS: This study demonstrates that GIPRs are expressed by human adipocytes, both GIPR mRNA and functional receptor expression being present in differentiated adipocytes but not in preadipocytes. Further investigation into the functional effects of GIP on differentiated SGBS cells could help towards understanding exactly how GIP regulates fat accumulation in human adipocytes.

Isolation of Langat virus from Haemaphysalis papuana Thorell in Thailand.

A strain of Langat virus (LGT), T-1674, was isolated from a pool of Haemaphysalis papuana Thorell collected in the forest of Khao Yai National Park in Central Thailand. The isolated virus was found to have growth and antigenic similarity to the prototype Langat strain (TP-21). This is the first report of a natural infection of Haemaphysalis ticks with LGT and of the isolation of this arbovirus in Thailand. The wide distribution of known vectors of LGT in Thailand suggests that the virus may be present in other areas of the country.

Analysis of Listeria monocytogenes by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations.

We examined 310 strains of Listeria monocytogenes by multilocus enzyme electrophoresis. Fifty-six electrophoretic types (ETs) of the organism were defined: 10 for serovar 4b strains, 11 for serovar 1/2b strains, and 30 for serovar 1/2a strains. Strains of serovars 1/2c, 3a, and 3b, and a non-typable strain were distributed among the remaining five ETs. The mean genetic diversity of the species was 0.41. Principal coordinate analysis revealed a sharp division among ETs which divided the species into two major clusters. ETs containing serovar 1/2a strains were in one cluster while all ETs containing serovar 4b, 1/2b, and 3b strains were in the second cluster. Except for two ETs that contained strains from both serovar 1/2b and serovar 3b, no ET contained strains from more than one serovar. Multilocus enzyme electrophoresis facilitated the analysis of epidemiologic data. In three separate epidemiologic investigations electrophoretic typing confirmed a common source as a cause of an outbreak; in a fourth investigation a single common source as a cause of an outbreak was effectively ruled out. Electrophoretic typing was also useful in documenting potential links between Listeria contaminated foods and persons with listeriosis who consumed those foods.

Reactions to acrylic resin dental prostheses.

A review of the pertinent literature concerning acrylic resin and its relation to allergic reactions and chemical injury has been presented. The relation of acrylic resin prostheses and materials to oral reactions and lesions is discussed and possible causes and means of evaluation are proposed. Examples of mucosal infection and mucosal disease are presented (which may mimic acrylic resin allergy) along with examples of direct chemical injury of the oral mucosa as a result of autopolymerizing prosthetic techniques.

Recognition of Pseudomonas pickettii in the clinical laboratory: biochemical characterization of 62 strains.

Pseudomonas pickettii strains were studied to determine the characteristics essential for their identification in the clinical microbiology laboratory. Preliminary investigations indicated that these glucose-oxidizing, denitrifying, gram-negative rods were quite similar to an unclassified group of clinical isolates designated VA-2. Gas liquid chromatography of trimethylsilyl derivatives of whole cell hydrolysates of P. pickettii and VA-2 strains yielded nearly identical elution profiles. The VA-2 cultures were concluded to be probable strains of P. pickettii. A method is presented for differentiating cultures of P. pickettii from other similar bacteria encountered in clinical specimens.

Dunnifilaria dilli sp. n. (Nematoda: Filarioidea) from Rattus koratensis in Thailand.

Dunnifilaria dilli, a new species of filariid from Rattus koratensis from Thailand is described. Adult worms were recovered from the lymphatic system. They differ from D. ramachandrani in their location in the host, the tail length, the shape of the spicules, and in the number of caudal papillae. Microfilariae are much smaller and unsheathed. Additional hosts include R. rattus and R. sabanus.

Comparison of thirty-seven strains of Vd-3 bacteria with Agrobacterium radiobacter: morphological and physiological observations.

Thirty-seven cultures of Vd-3 bacteria, isolated from clinical specimens, were characterized morphologically and physiologically. The cultures produced positive reactions when tested for oxidase, urease, nitrate reduction, phenylalanine deaminase, oxidative metabolism of carbohydrate substrates, and 3-ketolactose production. These peritrichously flagellated microorganisms were isolated primarily from the respiratory tract. When compared to authentic strains of Agrobacterium, they appeared to be most similar to A. radiobacter. Gas-liquid chromatography of trimethylsilyl derivatives of whole-cell hydrolysates of some of the Vd-3 strains and A. radiobacter yielded nearly identical elution patterns. The Vd-3 cultures were identified as probable strains of A. radiobacter. A method is presented for differentiating cultures of A. radiobacter from other similar bacteria encountered in clinical specimens. Although these bacteria rarely occur in clinical specimens, the clinical microbiologist should be familiar withe their outstanding characteristics.

Observation of nitrate reduction in some non-saccharolytic strains of Acinetobacter.

Clinical isolates of non-saccharolytic Acinetobacter species were observed to reduce nitrate.

Cellular fatty acid composition of Campylobacter fetus.

The cellular fatty acid composition of 29 human and animal isolates of Campylobacter fetus was determined with gas-liquid chromatography. All strains contained small amounts of 3-hydroxytetradecanoic acid, suggesting the presence of lipid A. Each of 13 different blood or stool isolates of C. fetus subsp. jejuni obtained from humans or fowl contained a 19-carbon cyclopropane acid which was not present in C. fetus subsp. fetus (6 strains from cattle) or C. fetus subsp. intestinalis (10 strains from humans and cattle). These findings indicate that C. fetus subsp. jejuni can be rapidly differentiated from other C. fetus by gas-liquid chromatography analysis of cellular fatty acids.

Neisseria lactamicus sp. n., a lactose-fermenting species resembling Neisseria meningitidis.

The biochemical and serological characteristics of lactose-utilizing strains of Neisseria were determined. These organisms were found in the nasopharynx of man and grew well on Thayer-Martin Selective Medium. They were compared with N. meningitidis to ascertain whether they were variants of this species. Differences between the lactose-using strains and the recognized species of Neisseria were considered significant enough to warrant designation of a new species, Neisseria lactamicus. This group has not been widely recognized as being separate from N. meningitidis; therefore, the normal incidence and clinical significance of these organisms has not been fully established. These organisms are oxidase-positive and positive for beta-D-galactosidase activity; they demonstrate fermentation in King Oxidation-Fermentation Medium; and they produce acid from only glucose, lactose, and maltose, of the 27 substrates incorporated in Cystine Trypticase Agar. Individual strains vary in their ability to grow on Nutrient Agar at both 25 and 37 C and in their pigmentation on Loeffler Medium. Results indicated that these organisms are serologically distinct from the N. meningitidis serogroups. Only 34 of 116 strains of N. lactamicus were smooth and could be tested by slide agglutination. None of the 34 could be grouped as N. meningitidis group A, B, C, D, X, Y, or Z. Thirty-one of these strains could, however, be specifically grouped with antisera prepared with N. lactamicus strains. Cross absorptions confirmed that N. lactamicus is serologically distinguishable from N. meningitidis.

Fatty acid composition of Neisseria species as determined by gas chromatography.

Duplicate cultures of 53 strains representing 9 species of Neisseria were analyzed by gas-liquid chromatography for cellular fatty acids. N. sicca, N. mucosa, N. flava, N. flavescens, N. perflava, N. subflava, and the several serotypes of N. meningitidis examined were found to comprise a fairly homogeneous group on the basis of the percentages of individual fatty acids present. Lactose-fermenting Neisseria also were in this group. N. catarrhalis, however, contained decanoic acid in addition to the acids occurring in the other species. Moreover, the 18 C-saturated and monoenoic acids together constituted 36% of the total fatty acid composition for N. catarrhalis, while the comparable mean value for the other species was less than 13%.

Deoxyribonucleic acid hybridization studies on Flavobacterium meningosepticum.

Seventeen flavobacteria, including 12 strains of Flavobacterium meningosepticum, were investigated to determine their genetic relationships by deoxyribonucleic acid (DNA)-DNA hybridization and guanine plus cytosine content. The percentage of binding among the strains tested ranged from 6 to 87%. There was no correlation between the serotype and DNA-duplex formation. The guanine plux cytosine content of the representative strains of the five serotypes ranged from 31 to 50%.

Cultural and biochemical characteristics and fatty acid composition of Pseudomonas diminuta and Pseudomonas vesiculare.

The cultural characteristics, biochemical activity, and cellular fatty acid composition of Pseudomonas diminuta and Pseudomonas vesiculare provided means for differentiation of these closely related species. Broth cultures of P. diminuta showed turbid growth and a distinct surface pellicle after 24 h at 35 C. P. vesiculare had no pellicle, and only light, diffuse growth was observed. All strains of P. vesiculare oxidized maltose and hydrolyzed esculin to varying degrees; P. diminuta was negative in these tests. The cellular fatty acids of these two species were similar, except that P. diminuta possessed a C19 cyclopropane acid which was not detected in P. vesiculare.

An unclassified gram-negative rod isolated from the pharynx on Thayer-Martin medium (selective agar).

An oxidase-positive, small gram-negative rod was isolated on Thayer-Martin medium (TM) inoculated with pharyngeal swabs obtained during surveys to detect Neisseria carriers. In one survey, this organism was isolated from 48% of the subjects, and 50 or more colonies were present on the majority of the primary isolation plates. Other characteristics of the organism, which has been given the provisional designation "TM-1," include: delayed production (2 to 10 days) of acid from glucose, formation of gas during nitrate reduction, and the frequent formation of "pits" in the agar surface. On TM, nonpitting colonies of TM-1 are morphologically similar to colonies of Neisseria gonorrhoeae and N. lactamica. Comparison of the characteristics of TM-1 strains with other similar fastidious gram-negative organisms encountered in clinical laboratories indicates that TM-1 is a distinct species. Further studies are required before proper taxonomic placement can be made.

Pseudomonas putrefaciens isolates from clinical specimens.

A total of 109 cultures of Pseudomonas putrefaciens isolated from clinical specimens were studied. The cultures were separated into two groups. The majority of the group 1 isolates, comprising 31 cultures, were characterized by (i) growth in plain nutrient broth, but no growth in broth supplemented with NaCl at concentrations of 7% and above, (ii) no growth on Salmonella-Shigella (SS) agar, and (iii) production of acid from the carbohydrates, sucrose, maltose, arabinose, and dextrin. Most group 2 isolates, comprising 78 cultures, were (i) unable to grow in plain nutrient broth, but grew well in broth supplemented with NaCl at a concentration of 7 to 10%, (ii) able to grow on SS agar, and (iii) unable to produce detectable amounts of acid from any of the carbohydrates tested except for variable results with glucose and fructose.

Cellular fatty acid composition of selected Pseudomonas species.

The cellular fatty acid composition of 10 reference strains representing eight species of Pseudomonas was determined by gas-liquid chromatography. A variety of acids were detected in these organisms, including branched and straight-chained acids, cyclopropane, and hydroxy acids. Comparison of the presence and relative amounts of these acids among strains was useful for distinguishing various Pseudomonas species.