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Biomedical subjects

M Brand

Publications and source records attributed to M Brand.

At least 19 recordsLinked to original sources
PubMed2006

Metabolic coronary flow regulation--current concepts.

The concept of metabolic coronary flow control provides a rationale for the close relationship of coronary flow and myocardial metabolic rate of oxygen. The concept is based on the presence of an oxygen (metabolic) sensor coupled functionally to effector mechanisms, which control vascular tone. Four modes of metabolic control models have been proposed. 1) An oxygen sensor located in the wall of coronary vessels coupling to smooth muscle tension. Endothelial prostaglandin production may support this concept. 2) An oxygen sensing mechanism located in the myocardium and changing metabolism in response to changes of local pO(2). Adenosine is a metabolite produced at an accelerated rate when the supply-to-demand relationship for oxygen falls. 3) Sensing of oxygen turnover may be achieved by carbon dioxide production and, potentially, by mitochondrial production of reactive oxygen species. 4) The red blood cell might serve as an oxygen sensor in response to changes of haemoglobin oxygenation. A potential link to vessel relaxation may be red cell ATP release. A large body of experimental evidence supports the notion that K(ATP) channels play a significant role causing smooth muscle hyper-polarization. However, additional yet unknown effector mechanisms must exist, because block of K(ATP) channels does not lead to deterioration of coronary flow control under conditions of exercise. Thus, although several lines of evidence show that metabolic flow regulation is effective during hypoxic conditions,mechanisms mediating normoxic metabolic flow control still await further clarification.

Adenosine↗
PubMed2005

Anosognosia in very mild Alzheimer's disease but not in mild cognitive impairment.

OBJECTIVE: To study awareness of cognitive dysfunction in patients with very mild Alzheimer's disease (AD) and subjects with mild cognitive impairment (MCI). METHODS: A complaint interview covering 13 cognitive domains was administered to 82 AD and 79 MCI patients and their caregivers. The patient groups were comparable according to age and education, and Mini Mental State Examination (MMSE) scores were > or =24 in all cases. The discrepancy between the patients' and caregivers' estimations of impairments was taken as a measure of anosognosia. RESULTS: Self-reports of cognitive difficulties were comparable for AD and MCI patients. However, while in comparison to caregivers MCI patients reported significantly more cognitive impairment (p < 0.05), AD patients complained significantly less cognitive dysfunctions (p < 0.001). CONCLUSIONS: While most MCI patients tend to overestimate cognitive deficits when compared to their caregiver's assessment, AD patients in early stages of disease underestimate cognitive dysfunctions. Anosognosia can thus be regarded as a characteristic symptom at a stage of very mild AD (MMSE > or =24) but not MCI. Accordingly, medical history even in mildly affected patients should always include information from both patient and caregiver.

Aged↗
PubMed2004

DemTect: a new, sensitive cognitive screening test to support the diagnosis of mild cognitive impairment and early dementia.

OBJECTIVES: To design a new, highly sensitive psychometric screening to identify patients with mild cognitive impairment (MCI) and patients with dementia in the early stages of the disease. METHODS: Five tasks were included in the DemTect: a word list, a number transcoding task, a word fluency task, digit span reverse, and delayed recall of the word list. The normation was performed with 145 healthy control subjects (CG). Furthermore, 97 MCI patients and 121 patients with possible Alzheimer's disease (AD) were tested with the DemTect and the MMSE. Classification rates for both tests were analysed. RESULTS: On the basis of the CG data, age-dependant transformation algorithms for the DemTect subtests were defined, and an education correction was provided for the total transformed score. The patient groups scored significantly below the CG in both the DemTect and the MMSE. Compared to the MMSE, classification rates of the DemTect were superior for both the MCI and the AD group, with high sensitivities of 80% and 100%, respectively. CONCLUSIONS: The DemTect is short (8-10 minutes), easy to administer, and its transformed total score (maximum 18) is independent of age and education. The DemTect helps in deciding whether cognitive performance is adequate for age (13-18 points), or whether MCI (9-12 points) or dementia (8 points or below) should be suspected.

Age Factors↗
PubMed2001

No evidence for bradykinin B1 receptors in rat dorsal root ganglion neurons.

Bradykinin receptors are believed to contribute to hyperalgesia under conditions of neuropathic pain. Using calcium imaging we investigated responses to B1 and B2 agonists on isolated rat dorsal root ganglion neurons. No response to the B1 agonist was detected, whereas 12% of neurons responded to the B2 agonist. Northern blot analysis confirmed the lack of B1 receptor expression in dorsal root ganglia, as B1 mRNA was neither detected under normal conditions nor after nerve injury. In the calcium imaging experiments, agonists were applied with an elevated superfusion flow rate to avoid tachyphylaxis to the drug. Normal external solution applied at this flow rate constituted a mechanical stimulus causing a response in some neurons. Thus, in comparable set-ups mechanosensitivity has first to be tested to avoid masking effects.

Animals↗
PubMed2001

UV-damaged DNA-binding protein in the TFTC complex links DNA damage recognition to nucleosome acetylation.

Initiation of transcription of protein-encoding genes by RNA polymerase II (Pol II) was thought to require transcription factor TFIID, a complex comprised of the TATA box-binding protein (TBP) and TBP-associated factors (TAF(II)s). In the presence of TBP-free TAF(II) complex (TFTC), initiation of Pol II transcription can occur in the absence of TFIID. TFTC containing the GCN5 acetyltransferase acetylates histone H3 in a nucleosomal context. We have identified a 130 kDa subunit of TFTC (SAP130) that shares homology with the large subunit of UV-damaged DNA-binding factor. TFTC preferentially binds UV-irradiated DNA, UV-damaged DNA inhibits TFTC-mediated Pol II transcription and TFTC is recruited in parallel with the nucleotide excision repair protein XP-A to UV-damaged DNA. TFTC preferentially acetylates histone H3 in nucleosomes assembled on UV-damaged DNA. In agreement with this, strong histone H3 acetylation occurs in intact cells after UV irradiation. These results suggest that the access of DNA repair machinery to lesions within chromatin may be facilitated by TFTC via covalent modification of chromatin. Thus, our experiments reveal a molecular link between DNA damage recognition and chromatin modification.

Acetylation↗
PubMed2001

Tight transcriptional control of the ETS domain factors Erm and Pea3 by Fgf signaling during early zebrafish development.

Several molecules of the Fibroblast growth factor family have been implicated in the development of the vertebrate brain, but the effectors of these molecules remain largely unknown. Here we study Erm and Pea3, two ETS domain transcription factors, and show that their expression correlates closely with the domains of fgf8 and fgf3 expression. In situ hybridization analysis in wild-type and acerebellar (ace) mutant embryos defective for fgf8 demonstrates a requirement of Fgf8 for normal expression levels of erm and pea3 transcripts in and close to various domains of Fgf8 action, including the prospective midbrain-hindbrain region, the somites, the neural crest, the forebrain, and developing eyes. Morpholino-oligomer-assisted gene knock-down experiments targeted against fgf8 and fgf3 suggest that Fgf3 and Fgf8 are co-regulators of these genes in the early forebrain anlage. Furthermore, inhibition of Fgf signaling by overexpression of sprouty4 or application of the Fgf inhibitor SU5402 leads to a loss of all erm and pea3 expression domains. Conversely, ectopically provided fgf3 mRNA or implanted beads coated with Fgf8 elicit ectopic transcription of erm and pea3. Both activation and loss of transcripts can be observed within short time frames. We conclude that both the transcriptional onset and maintenance of these factors are tightly coupled to Fgf signaling and propose that erm and pea3 transcription is a direct readout of cells to Fgf levels. Given the knowledge that has accumulated on the posttranslational control of ETS domain factors and their combinatorial interactions with other transcription factors, we suggest that the close coupling of erm and pea3 transcription to Fgf signaling might serve to integrate Fgf signaling with other signals to establish refined patterns in embryonic development.

Animals↗
PubMed2001

The midbrain--hindbrain boundary organizer.

Cell fate in the cephalic neural primordium is controlled by an organizer located at the midbrain-hindbrain boundary. Studies in chick, mouse and zebrafish converge to show that mutually repressive interactions between homeodomain transcription factors of the Otx and Gbx class position this organizer in the neural primordium. Once positioned, independent signaling pathways converge in their activity to drive organizer function. Fibroblast growth factors secreted from the organizer are necessary for, and sufficient to mimic, organizer activity in patterning the midbrain and anterior hindbrain, and are tightly controlled by feedback inhibition.

Animals↗
PubMed2001

The TFIID components human TAF(II)140 and Drosophila BIP2 (TAF(II)155) are novel metazoan homologues of yeast TAF(II)47 containing a histone fold and a PHD finger.

The RNA polymerase II transcription factor TFIID comprises the TATA binding protein (TBP) and a set of TBP-associated factors (TAF(II)s). TFIID has been extensively characterized for yeast, Drosophila, and humans, demonstrating a high degree of conservation of both the amino acid sequences of the constituent TAF(II)s and overall molecular organization. In recent years, it has been assumed that all the metazoan TAF(II)s have been identified, yet no metazoan homologues of yeast TAF(II)47 (yTAF(II)47) and yTAF(II)65 are known. Both of these yTAF(II)s contain a histone fold domain (HFD) which selectively heterodimerizes with that of yTAF(II)25. We have cloned a novel mouse protein, TAF(II)140, containing an HFD and a plant homeodomain (PHD) finger, which we demonstrated by immunoprecipitation to be a mammalian TFIID component. TAF(II)140 shows extensive sequence similarity to Drosophila BIP2 (dBIP2) (dTAF(II)155), which we also show to be a component of Drosophila TFIID. These proteins are metazoan homologues of yTAF(II)47 as their HFDs selectively heterodimerize with dTAF(II)24 and human TAF(II)30, metazoan homologues of yTAF(II)25. We further show that yTAF(II)65 shares two domains with the Drosophila Prodos protein, a recently described potential dTAF(II). These conserved domains are critical for yTAF(II)65 function in vivo. Our results therefore identify metazoan homologues of yTAF(II)47 and yTAF(II)65.

Amino Acid Motifs↗
PubMed2001

sprouty4 acts in vivo as a feedback-induced antagonist of FGF signaling in zebrafish.

In looking for novel factors involved in the regulation of the fibroblast growth factor (FGF) signaling pathway, we have isolated a zebrafish sprouty4 gene, based on its extensive similarities with the expression patterns of both fgf8 and fgf3. Through gain- and loss-of-function experiments, we demonstrate that Fgf8 and Fgf3 act in vivo to induce the expression of Spry4, which in turn can inhibit activity of these growth factors. When overexpressed at low doses, Spry4 induces loss of cerebellum and reduction in size of the otic vesicle, thereby mimicking the fgf8/acerebellar mutant phenotype. Injections of high doses of Spry4 cause ventralization of the embryo, an opposite phenotype to the dorsalisation induced by overexpression of Fgf8 or Fgf3. Conversely we have shown that inhibition of Spry4 function through injection of antisense morpholino oligonucleotide leads to a weak dorsalization of the embryo, the phenotype expected for an upregulation of Fgf8 or Fgf3 signaling pathway. Finally, we show that Spry4 interferes with FGF signaling downstream of the FGF receptor 1 (FGFR1). In addition, our analysis reveals that signaling through FGFR1/Ras/mitogen-activated protein kinase pathway is involved, not in mesoderm induction, but in the control of the dorsoventral patterning via the regulation of bone morphogenetic protein (BMP) expression.

Amino Acid Sequence↗
PubMed2000

Pharmacotherapy for hypertension in the elderly.

OBJECTIVES: To quantify the long-term effects of antihypertensive drug therapy on morbidity and mortality in the elderly. To characterize co morbid risk profiles of trial participants. SEARCH STRATEGY: Electronic search of WHO-ISH Collaboration register (August 1997), The Cochrane Library (1997; Issue 1), MEDLINE (1966 to April 1997) and two Japanese databases (1973-1995); references from reviews, trials and 10 previously published meta-analyses; and experts. SELECTION CRITERIA: Randomized controlled trials of at least one year duration in hypertensive elders (at least 60 years old) assessing antihypertensive drug therapy and providing morbidity and mortality data. DATA COLLECTION AND ANALYSIS: At least two independent reviewers abstracted data on morbidity and mortality results and trial characteristics. The following outcomes were assessed: total mortality; coronary heart disease (CHD) mortality; combined CHD morbidity and mortality; cerebrovascular mortality; combined cerebrovascular morbidity and mortality; cardiovascular mortality; combined cardiovascular morbidity and mortality; and drop outs due to side effects of treatment. MAIN RESULTS: Fifteen trials including 21,908 elderly subjects were identified. The average prevalence of cardiovascular risk factors, cardiovascular disease, and competing co morbid diseases was lower among trial participants than the general population of hypertensive elderly persons. Most subjects were 60 to 80 years old. Most trials were conducted in Western, industrialized countries and evaluated diuretic and beta-blocker therapies. Event rates per 1000 participants over approximately 5 years indicated that antihypertensive drug therapy was beneficial. Cardiovascular morbidity and mortality was reduced from 177 to 126 events (95% CI of the difference 31 to 73). Cardiovascular mortality was reduced from 69 to 50 deaths (95% CI of the difference 9 to 31). Total mortality was reduced from 129 to 111 deaths (95% CI of difference 4 to 28). The data from the three trials restricted to persons with isolated systolic hypertension indicated a significant benefit: cardiovascular morbidity and mortality over approximately 5 years was reduced from 157 to 104 events per 1000 participants (95% CI of the difference 12 to 89). Numbers of participants who dropped out of trials secondary to adverse drug effects were often not reported. The four trials that did report this data showed a wide variation in drop out rates ranging from no significant differences between treatment and control groups to as many as one out of four patients dropping out due to side effects of treatment. REVIEWER'S CONCLUSIONS: Randomized controlled trials establish that treating healthy older persons with hypertension is highly efficacious. Benefits of treatment with low dose diuretics or beta-blockers are clear for persons in their 60s to 70s with either diastolic or systolic hypertension. Differential treatment effects based on patient risk factors, pre-existing cardiovascular disease and competing co-morbidities could not be established from the published trial data.

Aged↗
PubMed2000

Inner ear and lateral line expression of a zebrafish Nkx5-1 gene and its downregulation in the ears of FGF8 mutant, ace.

An orthologue of the mouse homeobox gene Nkx5-1 was cloned and characterized in the zebrafish. As in the mouse and chick, the zebrafish Nkx5-1 gene is expressed in the ear placode and vesicle and in cells forming the vestibulo-acoustic ganglion. In addition, a novel expression domain, the lateral line, appears in the zebrafish, supporting a common precursor hypothesis for these two organs. In the FGF8 zebrafish mutant ace, expression of Nkx5-1 in the otic structures is diminished. The most significant reduction of zfNkx5-1 expression was observed in cells of the vestibulo-acoustic ganglion.

Amino Acid Sequence↗
PubMed2000

Overlapping and distinct functions provided by fgf17, a new zebrafish member of the Fgf8/17/18 subgroup of Fgfs.

Members of the fibroblast growth factor (Fgf) family are important signaling molecules in several inductive and patterning processes, and act as brain organizer-derived signals during formation of the early vertebrate nervous system. We isolated a new member of the Fgf8/17/18 subgroup of Fgfs from the zebrafish, and studied its expression and function during somitogenesis, optic stalk and midbrain-hindbrain boundary (MHB) development. In spite of a slightly higher aminoacid similarity to Fgf8, expression analysis and mapping to a chromosome stretch that is syntenic with mammalian chromosomes shows that this gene is orthologous to mammalian Fgf17. These data provide a further example of conserved chromosomal organization between zebrafish and mammalian genomes. Using an mRNA injection assay, we show that fgf17 can act similar to fgf8 during gastrulation, when fgf17 is not normally expressed. Direct comparison of the expression patterns of fgf17 and fgf8 suggest however a possible cooperation of these Fgfs at later stages in several tissues requiring Fgf signaling. Analysis of zebrafish MHB mutants demonstrates a gene-dosage dependent requirement of fgf17 expression for the no isthmus// pax2.1 gene, showing that no isthmus/pax2.1 functions upstream of fgf17 at the MHB in a haplo-insufficient manner, similar to what has been reported for mammalian pax2 mutants. In contrast, only maintenance of fgf17 expression is disturbed at the MHB of acerebellar/fgf8 mutants. Consistent with a requirement for fgf8 function, implantation of FGF8-soaked beads induces fgf17 expression, and expression is upregulated in aussicht mutants, which display upregulation of the Fgf8 signaling pathway. Taken together, our results argue that Fgf8 and Fgf17 act as hierarchically organized signaling molecules during development of the MHB organizer and possibly other organizers in the developing nervous system.

Amino Acid Sequence↗
PubMed2000

Anorexia nervosa in congenital adrenal hyperplasia: long-term follow-up of 4 cases.

Studies which evaluate the psychosocial development and integration of adult female congenital adrenal hyperplasia (CAH) patients are rare but show that patients with the salt wasting form are significantly more virilized and more frequently single and childless. Major complaints are irregular menstruation, hirsutism, acne, obesity, deep voice, and cushingoid features. Surprisingly, a higher prevalence of psychosomatic disorders has not yet been described. Since anorexia nervosa (AN) has not yet been described in patients with CAH, we here report 4 cases of female CAH patients who developed AN during adolescence. Diagnosis of CAH was made between the age of 10 days and 3 years. Three patients suffer from the simple-virilizing form of CAH, one patient has a mild salt wasting CAH. Genital malformation varied from Prader stage II to IV. All 4 patients were compound heterozygotes for mutations/deletions of the CYP21B gene. Control of substitution therapy consisting of hydrocortisone and fluorocortisone was good. AN developed at ages 12, 13, 17, and 21 years (ICD 10 criteria for AN are BMI below 17.5 kg/m2, deliberate weight loss, body image disturbance, and primary or secondary amenorrhoea). Diagnosis of AN was established by psychiatrists and/or psychologists. All four patients showed an impressive and deliberate weight loss between 13 and 20 kg within 6 months, had primary or secondary amenorrhoea, and presented with BMI between 13 and 17.9 kg/m2. All patients received psychological treatment and recovered. However, one patient had a severe relapse of AN. Two patients are now married and one has a healthy son. These cases demonstrate that the diagnosis of CAH is compatible with the development of AN and illustrate the importance of providing treatment for CAH patients that encompasses not only medical but also psychological and social care.

Adrenal Hyperplasia, Congenital↗
PubMed2000

Longitudinal analysis of growth over the first 3 years of life in Turner's syndrome.

OBJECTIVE: To evaluate longitudinal growth in Turner's syndrome (TS) over the first 3 years of life. METHODS: Growth of 47 patients with TS was compared with that of 40 age-matched control girls by using an analysis according to the Infancy-Childhood-Puberty and bi-exponential models. RESULTS: A mean of 1.2 SDs were lost before birth and a total of 3.0 SDs were lost by age 3 years. According to the Infancy-Childhood-Puberty model, intrauterine growth retardation contributed -1.24 SDs, a 5-month delay in childhood growth spurt contributed -0.96 SDs, and slow childhood growth contributed an additional -0.8 SDs by age 3 years. The bi-exponential analysis disclosed a quasi-linear first exponent and a confining second exponent, which merged at age 18 months in control subjects and 24 months in patients with TS. The first exponent confers an average annual growth rate of 8.4 cm/y in control subjects and 6.7 cm/y in patients with TS. CONCLUSIONS: Intrauterine growth retardation and the initial 3 years of life contribute most of the deficit in the final height of patients with TS. These data provide a reference of standards for longitudinal growth in patients with TS at age 3 months to 3 years.

Child, Preschool↗
PubMed2000

Characterization of adherence of nontypeable Haemophilus influenzae to human epithelial cells.

The adherence of 58 nontypeable Haemophilus influenzae isolates obtained from patients with otitis media or chronic obstructive pulmonary disease (COPD) and obtained from the throats of healthy individuals to Chang and NCI-H292 epithelial cells was compared. Otitis media isolates, but not COPD isolates, adhered significantly more to both cell lines than did throat isolates. Since high-molecular-weight (HMW) proteins are major adhesins of nontypeable H. influenzae, the isolates were screened for HMW protein expression by Western blotting with two polyclonal sera and PCR with hmw-specific primers. Twenty-three of the 32 adhering isolates (72%) and only 1 of the 26 nonadherent strains were HMW protein or hmw gene positive. Among the 32 isolates adhering to either cell line, 5 different adherence patterns were distinguished based on the inhibiting effect of dextran sulfate. Using H. influenzae strain 12 expressing two well-defined HMW proteins (HMW1 and HMW2) and its isogenic mutants as a reference, we observed HMW1-like adherence to both cell lines for 16 of the 32 adherent isolates. Four others showed HMW2-like adherence to NCI-H292. Of the three other patterns of adherence, one probably also involved HMW protein. Screening of the isolates with six HMW-specific monoclonal antibodies in a whole-cell enzyme-linked immunosorbent assay showed that the HMW proteins of COPD isolates and carrier isolates were more distinct from the HMW proteins from H. influenzae strain 12 than those from otitis media isolates. Characterization of the HMW protein of a COPD isolate by adherence and DNA sequence analysis showed that despite large sequence diversity in the hmwA gene, probably resulting in the antigenic differences, the HMW protein mediated the HMW2-like adherence of this strain.

Adhesins, Bacterial↗