Hypothermic circulatory arrest does not increase the risk of ascending thoracic aortic aneurysm resection

OBJECTIVE: The purpose of this study was to investigate the safety and efficacy of a period of deep hypothermic circulatory arrest (DHCA) during elective replacement of the ascending thoracic aorta. SUMMARY BACKGROUND DATA: DHCA has been implemented in ascending thoracic aortic aneurysm resection whenever the anatomy or pathology of the aorta or arch vessels prevents safe or adequate cross-clamping. Profound hypothermia and retrograde cerebral perfusion have been shown to be neurologically protective during ascending aortic replacement under circulatory arrest. METHODS: The authors conducted a retrospective analysis of 91 consecutive patients who underwent repair of chronic ascending thoracic aortic aneurysms from 1986 to present. The authors hypothesized that patients undergoing DHCA with or without retrograde cerebral perfusion during aneurysm repair were at no greater operative risk than patients who received aneurysm resection while on standard cardiopulmonary bypass. RESULTS: There were no significant differences in hospital mortality, stroke rate, or operative morbidity between patients repaired on DHCA when compared to those repaired on cardiopulmonary bypass. CONCLUSIONS: DHCA with or without retrograde cerebral perfusion does not result in increased morbidity or mortality during the resection of ascending thoracic aortic aneurysms. In fact, this technique may prevent damage to the arch vessels in select cases and avoid the possible complications associated with cross-clamping a friable or atherosclerotic aorta.     

Immunologic cross-reaction between HIV type 1 p17 and Mycoplasma hyorhinis variable lipoprotein

The last decade has seen a surge in the use of computerized health care data for pharmacoepidemiology. Of all European databases, the General Practice Research Database (GPRD) in the UK, has been the most widely used for pharmacoepidemiological research. Since 1994, this database has belonged to the UK Department of Health, and is maintained by the Office of National Statistics (ONS). Currently, around 1500 general practitioners with a population coverage in excess of 3 million, systematically provide their computerized medical data anonymously to ONS. Validation studies of the GPRD have documented the recording of medical data into general practitioners' computers to be near to complete. The GPRD collects truly population-based data, has a size that makes it possible to follow-up large cohorts of users of specific drugs, and includes both outpatient and inpatient clinical information. The access to original medical records is excellent. Desirable improvements to the GPRD would be additional computerized information on certain variables and linkage to other health care databases. Most published studies to date have been in the area of drug safety. The General Practice Research Database has proved that valuable data can be collected in a general practice setting. The full potential of this rich computerized database has yet to come. This experience should serve to encourage others to develop similar population-based data in other countries.     

Flt3high and Flt3low CD34+ progenitor cells isolated from human bone marrow are functionally distinct

We generated monoclonal antibodies against the human Flt3 receptor and used them to study the characteristics of normal human bone marrow cells resolved based on Flt3 expression. Human CD34+ or CD34+lin- marrow cells were sorted into two populations: cells expressing high levels of Flt3 receptor (Flt3high) and cells with little or no expression of Flt3 receptor (Flt3low). Flt3 receptor was detected on a subset of CD34+CD38- marrow cells, as well as on CD34+CD19+ B lymphoid progenitors and CD34+CD14+CD64+ monocytic precursors. Flt3 receptor was also present on more mature CD34-CD14+ monocytes. In colony-forming assays, Flt3high cells gave rise mainly to colony-forming unit-granulocyte-macrophage (CFU-GM) colonies, whereas Flt3low cells produced mostly burst-forming unit-erythroid colonies. There was no difference in the number of multilineage CFU-Mix colonies between the two cell fractions. Cell cycle analysis showed that a large number of the Flt3low cells were in the G0 phase of the cell cycle, whereas Flt3high cells were predominantly in G1. Cell numbers in the suspension cultures initiated with Flt3high cells were maintained in the presence of Flt3 ligand (FL) alone, and increased in response to FL plus kit ligand (KL). In contrast, cell numbers in the suspension cultures started with Flt3low cells did not increase in the presence of FL, or FL plus KL. Upregulation of Flt3 receptor on Flt3low cells was not detected during suspension culture. CD14+ monocytes were the major cell type generated from CD34+lin-Flt3high cells in liquid suspension culture, whereas cells generated from CD34+lin-Flt3low cells were mainly CD71+GlycA+ erythroid cells. These results show clear functional differences between CD34+Flt3high and CD34+Flt3low cells and may have implications concerning the in vitro expansion of human hematopoietic progenitor cells.     

About the pKa of the active-site histidine in flavocytochrome b2 (yeast L-lactate dehydrogenase)

Flavocytochrome b2 or L-lactate dehydrogenase from yeasts catalyzes the oxidation of L-lactate at the expense of monoelectronic acceptors such as cytochrome c, its physiological partner. When incubated in the presence of both L-lactate and a keto acid, the enzyme catalyzes a transhydrogenation reaction wherein only the flavin is involved. During this reaction, the substrate alpha-hydrogen is transferred not only to the solvent but also in part to the keto acid, which acts as reverse substrate. Thus, when bound to the reduced enzyme, this hydrogen is sticky. In the context of a carbanion mechanism, it resides on Nepsilon of His373, the active site base. We have shown before that a correlation between the amount of intermolecular hydrogen transfer from [2-3H] lactate and the keto acid reverse substrate concentration enables the determination of the first-order rate constant, kHe, for exchange of the substrate-derived protein-bound hydrogen with bulk solvent (Urban P, Lederer F, 1985, J Biol Chem 260:11115-11122). In this work, we show that the exchange with the solvent appears to be independent of the phosphate buffer concentration in the range from 40 to 500 mM. It is thus probable that exchange occurs directly with water molecules. The second-order rate constant for exchange is then 0.16 (+/-0.03) M(-1) s(-1). Using the Eigen equation, this figure yields a pKa of 9.1+/-0.1 for His373 in the reduced enzyme, compared to a probable value of 6.0 or less in the oxidized enzyme (Suzuki H, Ogura YC, 1970, J Biochem 67:291-295). The mechanistic significance of these results is discussed.     

Pulsed dye laser treatment of molluscum contagiosum in a patient with acquired immunodeficiency syndrome

We report an autopsy case of a malformed fetus with thymic hypoplasia. The autopsy was performed after therapeutic termination in the second trimester of pregnancy. The HIV-1 infected mother had received 3 antiviral agents and treatment for opportunistic infections.     

Imaging features and clinical significance of perineural spread or extension of head and neck tumors

Perineural spread of head and neck tumors is a form of metastatic disease in which tumor disseminates to noncontiguous regions along the endoneurium or perineurium. Both computed tomography (CT) and magnetic resonance (MR) imaging can help detect perineural spread, although MR imaging is the modality of choice because of its multiplanar capability, its superior soft-tissue contrast, and the decreased amount of artifact from dental hardware. Perineural spread most commonly occurs in adenoid cystic carcinoma and squamous cell carcinoma. Nerve enlargement may lead to foraminal enlargement and, ultimately, to foraminal destruction, findings that are best seen at CT. Extension through the foramen ovale and involvement of the Meckel cave is best seen on coronal T1-weighted MR images, and nerve enhancement is best seen on fat-suppressed T1-weighted MR images. Other radiologic findings include obliteration of fat planes at foraminal openings, neuropathic atrophy, cavernous sinus enlargement, and replacement of the trigeminal subarachnoid cistern with soft tissue. The pathway of perineural tumor spread is predictable with knowledge of the pertinent cranial nerve anatomy; however, patients with radiologically or pathologically proved perineural spread may have normal nerve function at clinical examination. Therefore, it is imperative that the radiologist be familiar with both normal cranial nerve anatomy and the radiologic appearance and assessment of perineural tumor extension.     

Two different genes encode ferrochelatase in Arabidopsis: mapping, expression and subcellular targeting of the precursor proteins

Six adolescents, five males with prolactin-secreting pituitary macroadenomas and one female with idiopathic hyperprolactinaemia, are described. Their ages at presentation ranged from 13 years 7 months to 16 years 6 months. Presenting symptoms included headache, visual field defect, arrested growth and puberty. Only two cases had galactorrhoea. Every case had an elevated serum prolactin level. Three had surgery before the results of serum prolactin were to hand. Each patient was treated with bromocriptine. Bromocriptine suppressed serum prolactin level to normal in four cases, but in the girl with idiopathic hyperprolactinaemia, bromocriptine was not useful. In two boys, serum prolactin was not suppressed with bromocriptine therapy alone, and they were subsequently treated with cabergoline, surgery and irradiation. Nevertheless, in children and adolescents with prolactin-secreting pituitary adenoma, bromocriptine should be the first line of treatment.     

27Al-NMR studies of aluminum transport across yeast cell membranes

Aluminum (Al) transport across yeast cells was studied using Dy(NO3)3 as a shift reagent by 27Al-NMR spectroscopy. The results showed that (a) Al enters the yeast cells at 15 min and over a period of time, within 4 h, an equilibrium sets in between outside and inside Al; (b) citrate does not favor Al going into the yeast cells at pH 5.0; and (c) EDTA brings out all the Al that has entered the yeast cells.     

The changing role of village health volunteers in northeast Thailand: an ethnographic field study

Aspergillus sinusitis is an uncommon complication of advanced human immunodeficiency virus (HIV) infection. We describe 2 patients with AIDS who developed histologically proven invasive Aspergillus sinusitis. We also review the findings of 14 histologically documented and 5 probable cases of invasive Aspergillus sinusitis. The literature on the prevalence, predisposing factors, diagnosis, treatment, and prognosis of the infection is reviewed. Major risk factors for the disease are advanced AIDS, chronic sinusitis or otitis, neutropenia, use of corticosteroids and prolonged use of broad spectrum antibiotics. The most common presenting symptoms are nonspecific and include fever, local pain, and swelling. Despite the newer diagnostic and therapeutic approaches discussed herein, the infection is usually fatal in HIV-infected patients. Early diagnosis and aggressive treatment remain the only available means to improve the currently dismal prognosis of Aspergillus sinusitis.