Role of the Haemophilus ducreyi Ton system in internalization of heme from hemoglobin

By cloning into Escherichia coli and construction of isogenic mutants of Haemophilus ducreyi, we showed that the hemoglobin receptor (HgbA) is TonB dependent. An E. coli hemA tonB mutant expressing H. ducreyi hgbA grew on low levels of hemoglobin as a source of heme only when an intact H. ducreyi Ton system plasmid was present. In contrast, growth on heme by the E. coli hemA tonB mutant expressing hgbA was observed only at high concentrations of heme, was TonB independent, and demonstrated that H. ducreyi HgbA was not sufficient to function as a typical TonB-dependent heme receptor in E. coli. Allelic replacement of the wild-type H. ducreyi exbB, exbD, and tonB loci with the exbB, exbD, and tonB deletion resulted in an H. ducreyi isogenic mutant unable to utilize hemoglobin but able to utilize hemin at the same levels as the parent strain to fulfill its heme requirement. This finding confirms the TonB dependence of HgbA-mediated hemoglobin utilization and suggests that uptake of hemin in H. ducreyi is TonB independent. Additionally, the H. ducreyi Ton system mutant synthesized increased amounts of HgbA and other heme-regulated outer membrane proteins, consistent with derepression of these proteins due to lower intracellular heme and/or iron concentrations in the mutant. Sequencing of the Ton system genes revealed that the arrangement of the genes was exbB exbD tonB. The proximity and structure of these genes suggested that they are transcribed as an operon. This arrangement, as well as the DNA and deduced amino acid sequences of these H. ducreyi genes, was most similar to those from other pasteurellae.

[Murderers in white coats--the physicians' plot against Stalin]

During the Moscow trials in 1936-38 several doctors were sentenced for participating in the murders of party leaders. As others who were accused, the doctors willingly confessed to crimes they could not possibly have committed. A second doctors' plot took place in the autumn of 1952. This time nine doctors, six of them Jews, were arrested for the attempted murder of political leaders. Only the unexpected death of Josef Stalin prevented a new wave of terror. With the single exception of Genrikh Grigorjevitsj Jagoda (1891-1938), head of the NKVD (KGB's predecessor), all those sentenced under the Moscow process are now rehabilitated. The participants of the second doctors' plot were rehabilitated immediately after Stalin's death.

Inhibition of angiogenesis by tissue inhibitor of metalloproteinase-3

PURPOSE

It has been established that Sorsby's fundus dystrophy, a dominantly inherited form of blindness, is caused by mutations in the tissue inhibitor of metalloproteinase-3 (TIMP-3) gene. Because choroidal neovascularization is a prominent feature of Sorsby's fundus dystrophy, the authors have examined whether TIMP-3 protein plays a role in the regulation of angiogenesis.

METHODS

Chemotaxis of endothelial cells toward vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) was examined using a modified Boyden chamber assay. Endothelial cells placed in the upper chamber were allowed to migrate through a polycarbonate membrane with 8 microns pores toward VEGF or bFGF present in the lower chamber. Next, the ability of TIMP-3 to inhibit chemotaxis was studied by incubating the cells with varying amounts of TIMP-3 during the assay. Finally, an in vitro angiogenesis assay was performed on collagen gels. Endothelial cells were seeded onto three-dimensional collagen gels. Treatment with bFGF and VEGF induced invasion of the gel and the formation of tube-like structures. TIMPs (1, 2, and 3) were added to the cultures to determine their effect on invasion. An in vivo chorioallantoic membrane (CAM) assay was performed using methylcellulose discs containing bFGF with or without TIMP-3. Induction of new blood vessels was observed with a stereomicroscope.

RESULTS

TIMP-3 inhibits chemotaxis of vascular endothelial cells toward VEGF and bFGF, inhibits collagen gel invasion and capillary morphogenesis in vitro, and inhibits bFGF-induced angiogenesis in the CAM assay in vivo.

CONCLUSIONS

TIMP-3 has the potential to inhibit angiogenesis. These results allow us to speculate on a possible mechanism by which mutant TIMP-3 protein might contribute to the Sorsby fundus dystrophy phenotype.

Leuconostoc spp. septicaemia in a child with short bowel syndrome

Septicaemia caused by the vancomycin-resistant Gram-positive bacteria Leuconostoc spp. is uncommon. We report a case of Leuconostoc spp. septicaemia in a child with short bowel syndrome fed through a central venous catheter and a gastrostomy. Leuconostoc spp. were isolated from several blood cultures. Despite several courses of antibiotics the fever continued and her condition deteriorated. After removal of the thrombotized central venous catheter her condition improved. Leuconostoc spp. was isolated from the thrombotic masses.

CD4 lymphopenia in a patient with cryptococcal osteomyelitis

Cryptococcus neoformans is a rarely reported cause of osteomyelitis. In most cases, no obvious underlying condition is found. Immunological laboratory data, however, are not generally available. In the present case of cryptococcal osteomyelitis, idiopathic CD4 lymphopenia was detected. This immunodeficiency is found in cases of disseminated cryptococcosis by chance. Possibly, it may be one so far unrecognized underlying condition in cryptococcal osteomyelitis.

Fourier transform infrared microspectroscopic analysis identifies alterations in mineral properties in bones from mice transgenic for type X collagen

Type X collagen has been implicated in the morphogenetic events of endochondral ossification (EO), including the calcification of hypertrophic cartilage and trabeculae prior to their replacement by bone and marrow. Recently, transgenic mice, which expressed a truncated collagen X protein, were reported to exhibit morphologic alterations in all tissues arising through EO. Specifically, the growth plates were compressed within the zone of cartilage hypertrophy, and the number and size of calcified trabeculae were reduced. The condition in the mouse is comparable to Schmid metaphyseal chondrodysplasia in humans for which, to date, 20 defined type X collagen mutations have been reported. The transgenic mouse showed no alterations in mineralization by conventional histology, however, it did show a decrease in newly formed bony trabeculae, and a thinning of periosteal bones. Fourier transform infrared (FTIR) spectroscopy has previously been shown to provide quantitative and qualitative information about the relative amount of mineral and carbonate present, mineral composition, and crystal perfection. To determine whether the expression of abnormal collagen X molecules had an effect on mineral properties, the "quality" of mineral crystals was analyzed in thin sections of tibia from day 17 and day 25 genotypically negative (normal) and positive (mutant) mice from several independent transgenic mouse lines showing varying degrees of the mutant phenotype, by means of Fourier transform infrared microscopic analysis (FTIRM). The results indicate definite differences between normal and transgenic mice calcified cartilage mineral, both in the amount present and the "quality" of the crystals. Calcified cartilage mineral from transgenic mice exhibited less crystallinity and higher acidic phosphate content than the corresponding mineral from normal specimens.

Congenital pseudarthrosis of the tibia

The present concepts of the aetiology, prevention and treatment of congenital pseudarthrosis of the tibia are discussed. The satisfactory results of Ilizarov's method and vascularised fibular grafting make these methods optimal choices for treatment. When they are not available, a bone graft with intramedullary fixation is a valuable alternative.

Canary finches (Serinus canaria) as an avian infection model for Lyme borreliosis

To investigate if passerine birds can be used as an avian model for Lyme borreliosis, the Borrelia burgdorferi sensu stricto strain Sh2-82 was inoculated subcutaneously on Canary finches (Serinus canaria). Spirochaetes could be detected in the blood by direct microscopy and an immunofluorescence assay (IFA) up to 2 weeks after the inoculation. DNA amplification (PCR) revealed B. burgdorferi DNA in the serum for up to 3 weeks, in the faeces up to 4 weeks, and from several internal organs at autopsy 3 months after the inoculation. Of particular interest was the finding of B. burgdorferi DNA in the liver of all birds at the end of the experiment, indicating a persistent infection. Four weeks after the primary infection, all infected birds showed an increase in anti Borrelia IgG antibodies and after 6 weeks all birds had seroconverted. Except for a brief episode of diarrhoea, none of the birds showed any signs of disease. This study shows that passerine birds experience short-term spirochaetemia after infection with B. burgdorferi, but show few clinical symptoms. This suggests that, although these birds can act as reservoirs of B. burgdorferi s.s., they may be of less importance as long lasting amplifiers for this pathogen.

Adult survivors of childhood sexual abuse. Do I have them in my practice?

The long term sequelae of childhood sexual abuse include many symptoms commonly encountered in general practice settings. Guidelines to empathic history taking, comprehensive assessment, and an overview of management are presented, together with a contextual background.

The role of type X collagen in endochondral ossification as deduced by Fourier transform infrared microscopy analysis

Type X collagen has been implicated in the morphogenetic events of endochondral ossification (EO), including the calcification of hypertrophic cartilage and trabeculae prior to their replacement by bone and marrow. Recently, transgenic mice which expressed a truncated collagen X protein were reported to exhibit morphologic alterations in all tissues arising through EO. Fourier Transform InfraRed (FTIR) spectroscopy has previously been shown to provide quantitative and qualitative information about the relative amount of mineral and carbonate present, mineral composition, and crystal perfection. To determine the role of collagen X in mineralization, the "quality" of mineral crystals was analyzed in thin sections of calcified cartilage from tibia obtained from several independent transgenic mouse lines showing varying degrees of the mutant phenotype and mice without type X collagen expression, by means of Fourier Transform InfraRed microscopy (FTIRM). In the present paper, the term "mineral quality" is employed to describe crystallinity/crystal maturation, and acid phosphate content. The results indicate significant differences between normal and transgenic mice bone mineral, both in the amount present and the "quality" of the crystals. In contrast, the analysis of the mineral in mice without type X collagen expression was not different from their age/sex-matched controls.

[Mikhail Bulgakov--a colleague and cult figure]

Mikhail Bulgakov (1891-1940) was medically qualified, but practised as a doctor only a few years before he launched on a full time career as a writer. His writings are marked by exuberant satire and burlesque phantasy, a genre condemned anti-Sovietic. Throughout his writing life, Bulgakov found it extremely difficult to get his writings published. He did not become known to the reading public inside and outside USSR until 30 years after his death.

Transhemispheric exchange of Lyme disease spirochetes by seabirds

Lyme disease is a zoonosis transmitted by ticks and caused by the spirochete Borrelia burgdorferi sensu lato. Epidemiological and ecological investigations to date have focused on the terrestrial forms of Lyme disease. Here we show a significant role for seabirds in a global transmission cycle by demonstrating the presence of Lyme disease Borrelia spirochetes in Ixodes uriae ticks from several seabird colonies in both the Southern and Northern Hemispheres. Borrelia DNA was isolated from I. uriae ticks and from cultured spirochetes. Sequence analysis of a conserved region of the flagellin (fla) gene revealed that the DNA obtained was from B. garinii regardless of the geographical origin of the sample. Identical fla gene fragments in ticks obtained from different hemispheres indicate a transhemispheric exchange of Lyme disease spirochetes. A marine ecological niche and a marine epidemiological route for Lyme disease borreliae are proposed.

Bacterial colonization of the larynx and trachea in healthy children

Fifty healthy children were included in the study; tracheal and laryngeal aspirations were performed after oral endotracheal intubation during minor surgery. The aspirates were evaluated and examined in the same way as aspirates from children suspected of pneumonia; 31 samples were accepted for the final analysis. After culturing, specimens from 30 children exhibited growth of potential pathogenic bacteria either from the larynx, the trachea or both. Prior to culture, bacteria were seen by microscopy in 24 samples from 30 children. These results indicate that the majority of healthy children carry potential pathogenic bacteria, not only in the larynx but also to a certain extent in the trachea. We conclude that aspirates from the larynx and the trachea are of limited value in the diagnosis of bacterial pneumonia in children.

Steroid hormone regulation and tissue-specific expression of the human GnRH gene in cell culture and transgenic animals

In order to study the molecular mechanisms involved in the control of GnRH gene expression, the human GnRH gene was cloned and characterized. The gene was expressed in cells obtained from CNS tumors in transgenic mice generated utilizing 1131 bp of 5' flanking GnRH DNA fused to the simian virus 40 large T antigen. We have shown a stimulatory estrogen response element in the human GnRH gene by transient transfection studies. DNase I footprinting and an avidinbiotin DNA binding assay demonstrated that the human GnRH gene bound ER. The GN cell line was found to have nuclear ERs utilizing an 125I estradiol binding study and by in situ hybridization histochemistry. In order to study GnRH expression in vivo, either 5000 or 484 bp of GnRH flanking DNA was fused to the luciferase (Luc) reporter gene, and transgenic mice generated. Expression in the transgenic animals was found in the hypothalamus of animals bearing the -5000Luc transgene, but not in animals bearing the -484Luc transgene. The transgenic mice expressing the -5000Luc gene were gonadectomized resulting in a 20-30% increase in hypothalamic Luc expression in the males and a 65% increase in females, while mice who were gonadectomized and replaced with testosterone (males) or E2 (females) showed a 50% decrease in Luc expression over control levels. Thus, these studies present in vitro evidence of E2 modulation of GnRH gene expression and an in vivo model in which sensitive studies of GnRH regulation and expression can be performed.