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Biomedical subjects

B Blum

Publications and source records attributed to B Blum.

At least 19 recordsLinked to original sources
PubMed2006

Efficient haemodialysis despite complete central venous thrombosis.

Two cases with a fully functional haemodialysis access, in spite of complete thrombotic occlusion of the ipsilateral subclavian and/or brachiocephalic vein are reported. The coincidentally detected complete venous occlusions may indicate that occult venous stenosis or thrombosis is more frequent than generally assumed. In order to avoid deterioration of the haemodynamic situation interventions may be withheld unless clinical problems related to a diminished outflow occur.

Aged↗
PubMed2004

Unusual cause of intermittent claudication.

Spontaneous dissection of a peripheral artery is a rare event. We report a case of a spontaneous, non-atherosclerotic and non-aneurysmal dissection limited to the external iliac artery in a 60-year-old woman who was admitted with a left calf claudication. Non-invasive examination documented signs of leg ischemia due to a floating wall dissection of the external iliac artery. After medical treatment over eight weeks the dissection membrane had been adapted to the vessel wall. A similar case of a spontaneous dissection limited to the external iliac artery, followed by a spontaneous healing has not been reported in the literature.

Aortic Dissection↗
PubMed2003

Anemia in chronic kidney disease and congestive heart failure.

Anemia is seen in chronic kidney insufficiency (CKI), dialysis patients, congestive heart failure (CHF), and renal transplantation. Anemia can lead to progressive cardiac damage as well as progressive renal damage. It is not generally appreciated that CHF itself may be a very common contributor to both the production of anemia as well as to the progression of the renal failure. Correction of the anemia with erythropoietin and, as necessary, intravenous iron, may prevent the deterioration of both the heart and the kidneys. We suggest that there is a triangular relationship, a vicious circle, between CHF, CKI and anemia where each of these three can both cause and be caused by the other. We call this syndrome the cardio-renal anemia (CRA) syndrome. All physicians, especially cardiologists and internists who treat CKI and CHF, should be made aware of the dangers of anemia in CKI and CHF and should work with nephrologists to correct it.

Anemia↗
PubMed2000

Antimycin A resistance in a mutant Leishmania tarentolae strain is correlated to a point mutation in the mitochondrial apocytochrome b gene.

In this paper we report the first case of antimycin A resistance in a protozoan parasite that is attributable to a mutation in the mitochondrial apocytochrome b (CYb) gene. We selected for, and isolated, a mutant Leishmania tarentolae strain that is resistant to antimycin A. This resistance was evident at the levels of the in vitro growth and enzymatic activity of the cytochrome bc1 complex. Molecular characterisation of the mutant revealed a Ser35Ile mutation in the expected region of the CYb gene. In kinetoplastids, CYb and other structural genes of the mitochondrial genome are located on the maxicircle component of the mitochondrial DNA, which is present in 20-50 copies. Primer-extension analysis confirmed the presence of the mutation at the mRNA level. The phenotypic manifestation of the mutation implies that the CYb mRNA is edited and translated within the mitochondrion. Thus, this finding provides direct evidence that edited RNAs are translated in kinetoplastid mitochondria. Furthermore, a defined mutation conferring drug resistance to a mitochondrial gene product can be exploited for the development of mitochondrial transfection systems for trypanosomatids.

Amino Acid Sequence↗
PubMed1999

The use of transgenic Trypanosoma brucei to identify compounds inducing the differentiation of bloodstream forms to procyclic forms.

The expression of procyclins is the earliest known marker of differentiation of bloodstream forms of Trypanosoma brucei to procyclic forms. We have generated transgenic bloodstream and procyclic forms in which the coding region of one procyclin gene was replaced by E. coli beta-glucuronidase (GUS). GUS activity can be monitored in a simple one-step colour reaction in microtitre plates; this assay is potentially suitable for large-scale screening for compounds that influence differentiation. GUS was stage-specifically expressed in procyclic forms and its synthesis occurred in parallel with that of procyclin when bloodstream forms were triggered to differentiate by the addition of cis-aconitate. GUS could also be induced by brief treatment with the proteases trypsin, pronase or thermolysin, but not with pepsin or thrombin. Interestingly, a combination of one of the active proteases with cis-aconitate resulted in increased GUS activity relative to either trigger alone. In contrast to cis-aconitate, protease treatment resulted in considerable cell death. Experiments with the pleomorphic strain AnTat 1.1 showed that long slender bloodstream forms were rapidly killed by proteases, whereas stumpy forms were largely resistant. Stumpy forms treated with trypsin differentiated synchronously and expressed procyclin with faster kinetics than when they were triggered by cis-aconitate. As predicted by the GUS assay, differentiation was even more rapid when both inducers were used simultaneously, with all cells expressing maximal levels of procyclin within 3 h.

Aconitic Acid↗
PubMed1999

Evaluation of laser doppler flowmetry for the study of benign and malignant gastric blood flow in vivo.

BACKGROUND: Tumour vascularisation is a determinant of the development of metastases. AIMS: To measure blood flow in normal stomach and gastric adenocarcinomas by laser Doppler flowmetry and correlate blood flow with vascularisation after immunohistochemical staining of resected specimens for CD31 and von Willebrand factor. PATIENTS: Twenty two undergoing resection for gastric adenocarcinoma and 10 undergoing cholecystectomy. RESULTS: Mean (SD) gastric blood flow was 208 (35) perfusion units (PU) in patients undergoing cholecystectomy and 190 (75) PU in the undiseased part of the stomach in patients with gastric adenocarcinoma. Gastric blood flow was higher in the border of gastric adenocarcinomas (322 (120) PU, p<0.01 v normal stomach) but lower in the centre (74 (27) PU, p<0.01 v normal stomach and tumour border). Blood flow was higher in tumours staged T>/=3 than in those staged T<3. Blood vessel density in normal stomach was 41 (8) stained cells/field viewed and was 1. 9-3.4 times higher in gastric adenocarcinomas. CONCLUSION: Laser Doppler flowmetry is a valuable tool for studying the pathophysiological alterations of malignant blood flow in the human stomach in vivo.

Adenocarcinoma↗
PubMed1998

In vivo import of unspliced tRNATyr containing synthetic introns of variable length into mitochondria of Leishmania tarentolae.

The mitochondrial genomes of trypanosomatids lack tRNA genes. Instead, mitochondrial tRNAs are encoded and synthesized in the nucleus and are then imported into mitochondria. This also applies for tRNATyr, which in trypanosomatids contains an 11 nt intron. Previous work has defined an exon mutation which leads to accumulation of unspliced precursor tRNATyr. In this study we have used the splicing-deficient tRNATyr as a vehicle to introduce foreign sequences into the mitochondrion of Leishmania tarentolae. The naturally occurring intron was replaced by synthetic sequences of increasing length and the resulting tRNATyr precursors were expressed in transgenic cell lines. Whereas stable expression of precursor tRNAsTyr was obtained for introns up to a length of 76 nt, only precursors having introns up to 38 nt were imported into mitochondria. These results demonstrate that splicing-deficient tRNATyr can be used to introduce short synthetic sequences into mitochondria in vivo. In addition, our results show that one factor which limits the efficiency of import is the length of the molecule.

Animals↗
PubMed1998

Suicide by cop.

STUDY OBJECTIVE: "Suicide by cop" is a term used by law enforcement officers to describe an incident in which a suicidal individual intentionally engages in life-threatening and criminal behavior with a lethal weapon or what appears to be a lethal weapon toward law enforcement officers or civilians to specifically provoke officers to shoot the suicidal individual in self-defense or to protect civilians. The objective of this study was to investigate the phenomenon that some individuals attempt or commit suicide by intentionally provoking law enforcement officers to shoot them. METHODS: We reviewed all files of officer-involved shootings investigated by the Los Angeles County Sheriff's Department from 1987 to 1997. Cases met the following criteria: (1) evidence of the individual's suicidal intent, (2) evidence they specifically wanted officers to shoot them, (3) evidence they possessed a lethal weapon or what appeared to be a lethal weapon, and (4) evidence they intentionally escalated the encounter and provoked officers to shoot them. RESULTS: Suicide by cop accounted for 11% (n=46) of all officer-involved shootings and 13% of all officer-involved justifiable homicides. Ages of suicidal individuals ranged from 18 to 54 years; 98% were male. Forty-eight percent of weapons possessed by suicidal individuals were firearms, 17% replica firearms. The median time from arrival of officers at the scene to the time of the shooting was 15 minutes with 70% of shootings occurring within 30 minutes of arrival of officers. Thirty-nine percent of cases involved domestic violence. Fifty-four percent of suicidal individuals sustained fatal gunshot wounds. All deaths were classified by the coroner as homicides, as opposed to suicides. CONCLUSION: Suicide by cop is an actual form of suicide. The most appropriate term for this phenomenon is law enforcement-forced-assisted suicide. Law enforcement agencies may be able to develop strategies for early recognition and handling of law enforcement-forced-assisted suicide (suicide by cop). Health care providers involved in the evaluation of potentially suicidal individuals and in the resuscitation of officer-involved shootings should be aware of law enforcement-forced-assisted suicide as a form of suicide.

Adolescent↗
PubMed1998

PET with 18fluorodeoxyglucose and hexamethylpropylene amine oxime SPECT in late whiplash syndrome.

BACKGROUND: Many patients have cognitive abnormalities and psychological problems after whiplash injury to the cervical spine. To our knowledge, neuroradiologic imaging has not depicted brain damage that explains the symptoms. Parietotemporo-occipital perfusion deficits on hexamethylpropylene amine oxime (HMPAO) SPECT studies have been described among patients who have sustained whiplash injury. METHODS: We examined 13 patients with typical late whiplash syndrome (study group) using HMPAO SPECT, 18fluorodeoxyglucose (FDG) PET, and MRI of the brain and compared the findings with those for 16 control subjects who underwent FDG PET. RESULTS: In the study group, statistical parametric mapping revealed significantly decreased FDG uptake in the frontopolar and lateral temporal cortex and in the putamen. The frontopolar hypometabolism correlated significantly with scores of the Beck Depression Inventory. However, in individual cases, reliability in the depiction of hypometabolic areas was relatively low. No alterations were found in the parietotemporo-occipital area. In these areas, decreased uptake of HMPAO and FDG correlated with cortical mass. CONCLUSION: FDG PET did not allow reliable diagnosis of metabolic disturbances for individual patients. Therefore, we do not recommend FDG PET or HMPAO SPECT as a diagnostic tool in routine examinations of patients with late whiplash syndrome.

Adult↗
PubMed1997

Theophylline and warfarin interaction studies with grepafloxacin.

Two phase I trials, each involving 16 healthy adult volunteers, were performed to investigate possible interactions between grepafloxacin and theophylline or warfarin. In the theophylline study, grepafloxacin 600 mg was administered once daily for 10 days to 12 volunteers who were receiving a maintenance dose of theophylline. This dose of theophylline was designed to produce mean serum theophylline concentrations of 7.5 mg/L; 4 volunteers received theophylline plus placebo. Pharmacokinetic parameters of theophylline were determined before grepafloxacin treatment and on day 10 of grepafloxacin or placebo administration. Peak theophylline concentrations and the area under the concentration-time curve increased significantly during grepafloxacin treatment, and apparent total clearance of theophylline was reduced by approximately 50%. No changes were observed in the placebo group and theophylline appeared to have no effect on the pharmacokinetics of grepafloxacin. In the warfarin study, grepafloxacin 600 mg was given once daily for 14 days to volunteers receiving a maintenance dose of warfarin. Warfarin was discontinued during the last 4 days of grepafloxacin administration. The pharmacodynamics of warfarin did not change after administration of grepafloxacin. Similarly, warfarin had no significant effect on the pharmacokinetics of grepafloxacin. We conclude that during treatment with grepafloxacin maintenance, doses of theophylline should be reduced by 50%, and we recommend that serum concentrations of theophylline be monitored during treatment with grepafloxacin. However, no dose adjustment is necessary for grepafloxacin when it is coadministered with theophylline, and dose adjustment does not seem to be required in concomitant treatment with grepafloxacin and warfarin.

Administration, Oral↗
PubMed1997

The Pseudomonas aeruginosa outer membrane protein I vaccine: immunogenicity and safe administration in man.

After expression in Escherichia coli and purification by Ni++ chelate-affinity chromatography, the outer membrane protein I (OprI) of Pseudomonas aeruginosa was tested in experimental animals for its safety and pyrogenicity. Four groups of 7 adult human volunteers were then vaccinated 3 times at four-weekly intervals with either 500 micrograms, 200 micrograms, 50 micrograms or 20 micrograms of OprI adsorbed onto aluminum hydroxide. The vaccinations were well tolerated and without systemic side effects, but a significant rise of antibody titers against OprI was measured in the serum of those who had received the 500 micrograms, 200 micrograms or 50 micrograms doses. Raised antibody titers against OprI were still present 30 weeks after the final vaccination. It was possible to demonstrate binding of the complement component C1q to the elicited antibodies, and this confirms their ability to promote antibody-mediated complement-dependent opsonization.

Adult↗
PubMed1996

Safety and immunogenicity of a Pseudomonas aeruginosa outer membrane protein I vaccine in human volunteers.

The outer membrane protein I (OprI) of Pseudomonas aeruginosa was expressed in Escherichia coli and purified by Ni2+ chelate-affinity chromatography. After safety and pyrogenicity evaluation in animals, four groups of seven adult human volunteers were vaccinated three times at four week intervals with either 500 micrograms, 200 micrograms, 50 micrograms or 20 micrograms of OprI adsorbed onto Al(OH)3. All vaccinations were well tolerated and no systemic side effects were detected. A significant rise of antibody titers against OprI could be measured in the serum of all volunteers who had received the 500 micrograms, 200 micrograms or 50 micrograms doses. Elevated antibody titers against OprI could still be measured 30 weeks after the final vaccination. Binding of the complement component C1q to the elicited antibodies could be demonstrated, showing the ability of the latter to promote antibody-mediated complement-dependent opsonization.

Adult↗
PubMed1995

TH1 cells trigger tumor necrosis factor alpha-mediated hypersensitivity to Pseudomonas aeruginosa after adoptive transfer into SCID mice.

Recent experiments have shown that gamma interferon (IFN-gamma), either administered or induced in vivo, e.g., by certain bacteria, is a key mediator in inducing hypersensitivity to bacterial lipopolysaccharides. The source of endogenous IFN-gamma in this context (natural killer versus TH1 cells) has not been investigated yet. In order to investigate the role of antigen-specific, IFN-gamma-producing TH1 cells in murine Pseudomonas aeruginosa infection, a murine TH1 cell line was propagated in vitro by using recombinant P. aeruginosa outer membrane protein I. Adoptive transfer experiments were performed by intravenous injection of various amounts of TH1 cells into P. aeruginosa-challenged SCID mice. Adoptive transfer of 5 x 10(6) T cells into SCID mice followed by an intraperitoneal challenge with 1.4 x 10(6) CFU of live P. aeruginosa resulted in the rapid death of the animals within 12 h postchallenge, whereas transfer of lower T-cell doses and saline as a control did not cause any detrimental effects. After challenge with 2.8 x 10(6) CFU of P. aeruginosa, similar results were obtained 18 h postchallenge; however, at the end of the 72-h observation period, no significant differences in survival rates were obtained between the groups treated with different amounts of T cells. The rapid death of mice treated with 5 x 10(6) T cells was reflected by 860-fold-elevated levels of tumor necrosis factor alpha (TNF-alpha) present in serum 2 h postchallenge, whereas no significant differences in TNF-alpha serum levels were detectable in mice treated with lower doses of T cells or with saline. Pretreatment of T-cell-reconstituted SCID mice with neutralizing anti-IFN-gamma monoclonal antibodies completely protected mice from bacterial challenge and reduced TNF-alpha levels in serum. We conclude that under the experimental conditions described here, IFN-gamma- and interleukin-2-producing TH1 cells represent an important trigger mechanism inducing TNF-alpha-mediated hypersensitivity to bacterial endotoxin.

Animals↗
PubMed1995

Responses to colour of neurones in area 7a of the inferior parietal lobule of the rhesus monkey.

A single-unit study on area 7a of alert, fixating rhesus monkeys revealed responsiveness to primary colours comparable to white light responsiveness shown in other cells. Mostly decremented, some biphasic, and a small portion with incremented neuronal firing response were observed, following stimulation of cells by parafoveal receptive field, rectangular, approximately 20 degrees x 20 degrees red, green or blue-violet light stimuli. The same cell showed no response to white light. Receptive fields of these colour-sensitive cells, like those of white-sensitive cells, were mostly contralateral, some ipsilateral and a few in both hemifields. Augmentation of responses following preconditioning electrical stimulation of lateroposterior-pulvinar targets was observed as with the white-light sensitive cells. It is noteworthy that this monkey area 7a colour sensitivity is complementary to previously demonstrated white light sensitivity. The specific properties revealed by these cells suggest separate channels within area 7a for colour and for achromatic light, the colour sensitivity possibly relevant when chromaticity is of generalized import, and these may subserve the animal's orienting response to colour appearance in the near-periphery visual field.

Action Potentials↗
PubMed1994

Organ-localized hypothalamic-stimulated vasculature changes in the cat.

Stimulation of specific lateral hypothalamic targets in a cat model induces vascular and/or cardiac changes. Evidence is presented that these may consist of discretely localized sympathetically mediated changes taking place in just one or two organs. Moreover, following stimulation of either one of two adjacent lateral hypothalamus sites, pressor effects are induced that superficially look similar, but prove to be mediated by different pathways. To investigate possible synapsing at sympathetic ganglia, e.g. in superior cervical or stellate ganglia, 50 micrograms atropine methyl nitrate, a ganglionic blocker, was applied directly to the ganglia. This was shown to potentiate the pressor effects, in some cases when applied to the superior cervical ganglia, in others to stellate ganglia, presumably by blockade of a ganglionic attenuating mechanism. The contributions made by different sympathetic nerves to the lateral hypothalamus-induced pressor effect were analysed. Stimulation of one of the lateral hypothalamus sites (TAR.I) in eight cats induced a pressor effect that was abolished by severing a nerve branch, from the superior cervical ganglia laterally, shown to innervate neck muscle vasculature. In another group of nine cats stimulation of TAR.II induced a pressor effect abolished by cutting a branch from the superior cervical ganglia medially, shown to be destined to the vasculature of pharyngeal muscles and possibly lower respiratory tract. The hypothesis that central control via the sympathetic nervous system is responsible for differential organ specific regulation of blood flow to individual organs is discussed.

Animals↗
PubMed1994

Protection of immunosuppressed mice against translocation of Pseudomonas aeruginosa from the gut by oral immunization with recombinant Pseudomonas aeruginosa outer membrane protein I expressing Salmonella dublin.

AroA Salmonella dublin was used as recipient for a plasmid coding for the outer membrane protein I (OprI) of Pseudomonas aeruginosa. Oral immunization of Balb/c mice with recombinant S. dublin induced serum IgG and IgA antibodies against P. aeruginosa. In spleen and Peyer's patches anti-P. aeruginosa IgG- and IgA-secreting cells could be measured by the ELISPOT technique. In an oral challenge of immunosuppressed mice with P. aeruginosa the orally immunized animals had a 58-fold higher LD50 than control animals.

Administration, Oral↗