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Biomedical subjects

D Schmidt

Publications and source records attributed to D Schmidt.

At least 109 records · Page 6Linked to original sources
PubMed2001

VHL c.505 T>C mutation confers a high age related penetrance but no increased overall mortality.

BACKGROUND: Germline mutations of the VHL gene cause von Hippel-Lindau syndrome (VHL). In southern Germany, a specific mutation in this gene, c.505 T>C, is one of the most frequent alterations owing to a founder effect. METHODS: This study was conducted to evaluate morbidity, specific clinical risk profile, and mortality among a series of VHL c.505 T/C mutation carriers. A total of 125 eligible subjects carrying VHL c.505 T/C underwent ophthalmoscopy and gadolinium enhanced magnetic resonance imaging of the brain, the spinal cord, and the abdomen. Age related penetrance, morbidity, and mortality were assessed. RESULTS: Frequently observed lesions were phaeochromocytoma (47%), retinal angiomas (36%), haemangioblastoma of the spine (36%), and haemangioblastoma of the brain (16%). Four patients developed renal cell carcinoma. VHL was symptomatic in 47% of subjects; 30% were asymptomatic despite the presence of at least one VHL related tumour and 23% of the carriers had no detectable VHL lesion. Of the 19 patients who had died (15%), 10 died of symptomatic VHL lesions. Overall penetrance by cumulative incidence functions is estimated at 48% by 35 years and 88% by 70 years. In contrast to the only existing published report based on patients with presumably unselected VHL germline mutations, the mortality rate for c.505 T/C mutation carriers is comparable to that of the general population of Germany. CONCLUSIONS: Our results are an important example that a specific genotype, at least in the case of VHL c.505 T/C, can favourably impact on mortality despite a high age related penetrance. Our study also indirectly provides objective data which might be useful to the life and health insurance industry; it would appear that c.505 T>C mutation positive subjects have similar disease specific mortality to that of the general population owing to a combination of phenotype and timely detection of mutation carrier status followed by aggressive clinical screening and, if necessary, treatment.

Adolescent↗
PubMed2001

Construction of a YAC library from barley cultivar Franka and identification of YAC-derived markers linked to the Rh2 gene conferring resistance to scald (Rhynchosporium secalis).

The Rh2 resistance gene of barley (Hordeum vulgare) confers resistance against the scald pathogen (Rhynchosporium secalis). A high-resolution genetic map of the Rh2 region on chromosome I (7H) was established by the use of molecular markers. Tightly linked markers from this region were used to screen existing and a newly constructed yeast artificial chromosome (YAC) library of barley cv. Franka composed of 45,000 clones representing approximately two genome equivalents. Corresponding YAC clones were identified for most markers, indicating that the combined YAC library has good representation of the barley genome. The contiguous sets of YAC clones with the most tightly linked molecular markers represent entry points for map-based cloning of this resistance gene.

Chromosomes, Artificial, Yeast↗
PubMed2001

CSF norepinephrine concentrations in posttraumatic stress disorder.

OBJECTIVE: Despite evidence of hyperresponsive peripheral and central nervous system (CNS) noradrenergic activity in posttraumatic stress disorder (PTSD), direct measures of CNS norepinephrine in PTSD have been lacking. The goal of this study was to determine serial CSF norepinephrine levels in patients with PTSD. METHOD: CSF samples were obtained serially over a 6-hour period in 11 male combat veterans with chronic PTSD and eight healthy men through an indwelling subarachnoid catheter. Thus the authors were able to determine hourly CSF norepinephrine concentrations under baseline (unstressed) conditions. Severity of the patients' PTSD symptoms was assessed with the Clinician-Administered PTSD Scale. RESULTS: CSF norepinephrine concentrations were significantly higher in the men with PTSD than in the healthy men. Moreover, CSF norepinephrine levels strongly and positively correlated with the severity of PTSD symptoms. Plasma norepinephrine concentrations showed no significant relationship with the severity of PTSD symptoms. CONCLUSIONS: These findings reveal the presence of greater CNS noradrenergic activity under baseline conditions in patients with chronic PTSD than in healthy subjects and directly link this pathophysiologic observation with the severity of the clinical posttraumatic stress syndrome.

Adult↗
PubMed2001

[Massive intestinal hemorrhage as the first sign of diverticular disease of the colon].

Retrospective and prospective analysis of massive enterorrhagia (m.e.). The aim of the study is the analysis of frequent causes of m.e--diverticular disease of the colon (DDC). The total number of patients with m.e. was 154 and the proportion of DDC in this total group was 17%, i.m. 24 patients. The total number of patients with the acute symptomatic DDC was 198 and the proportion of haemorrhagic DDC in this total group was 13.3%. The dominant form is conservative therapy (88.4%), surgical therapy was performed in 11.6% of cases. Discontinuous types of operations predominated. The analysis of the group and comparison with problems of m.e. in the literature.

Acute Disease↗
PubMed2001

[Primary tumors of the liver: radiologic interventional procedures].

Primary liver tumors are one of the most common malignant tumors worldwide. Surgical resection of the tumors is considered the only potentially curative therapy. It has been estimated that only 20%-30% of patients with HCC (hepatocellular carcinoma) are surgical candidates. For this reason a number of alternative therapies have been used for the treatment of HCC. These include transarterial chemoembolisation (TACE), percutaneous alcohol instillation (PAI) and thermal ablative techniques. Thermal ablation for the treatment of HCC include both freezing (cryoablation) and heating (radiofrequency, microwave, laser and high-intensity focussed sonography) techniques. Of these techniques, percutaneous radiofrequency ablation (PRFA) is increasingly used for the local tumor destruction. The low rate of complications and the technical development increasing the efficacy of PRFA have shown that this is a very promising and safe technique.

Angiography↗
PubMed2000

Chemoenzymatic synthesis of sialyl oligosaccharides with sialidases employing transglycosylation methodology.

A series of sialyloligosaccharides was synthesized using the transglycolytic activity of the sialidases from Vibrio cholerae, Clostridium perfringens, Salmonella typhimurium, and Newcastle disease virus. According to their hydrolytic activities the sialidases from V. cholerae and C. perfringens catalyze preferentially the formation of sialyl alpha(2-6)-linkages whereas the sialidases from S.typhimurium and Newcastle disease virus show a distinct preference for alpha(2-3) directed sialylations. Using combined chemical and enzymatic methodologies structures such as T-(Thomsen-Friedenreich) antigen [beta-D-Gal-(1-3)-alpha-D-GalNAc-OThr], Tn-(Thomsen nouveau) antigen (alpha-D-GalNAc-OThr) and beta-D-Gal-(1-4)-alpha-D-2-deoxy-Gal-OMe were sialylated in alpha(2-3)- and alpha(2-6)-positions regioselectively or in high regioisomeric excess and purified by simple isolation procedures. Depending on the enzyme source and acceptor structure yields for transsialylation varied between 10 and 30%.

Carbohydrate Conformation↗
PubMed2000

The translating brain: cerebral activation patterns during simultaneous interpreting.

Brain activation was measured in professional interpreters during simultaneous interpreting (SI) vs. repetition (shadowing) of auditorily presented text by positron emission tomography (PET). SI into the native language (Finnish) elicited left frontal activation increases. SI into the non-native language (English) elicited much more extensive left-sided fronto-temporal activation increases. Our results indicate that SI activates predominantly left-hemispheric structures (particularly the left dorsolateral frontal cortex) previously related to lexical search, semantic processing and verbal working memory. Brain activation patterns were clearly modulated by direction of translation, with more extensive activation during translation into the non-native language which is often considered to a be more demanding task.

Adult↗
PubMed2000

Evidence of a source of HIV type 1 within the central nervous system by ultraintensive sampling of cerebrospinal fluid and plasma.

Defining the source of HIV-1 RNA in cerebrospinal fluid (CSF) will facilitate studies of treatment efficacy in the brain. Four antiretroviral drug-naive adults underwent two 48-hr ultraintensive CSF sampling procedures, once at baseline and again beginning on day 4 after initiating three-drug therapy with stavudine, lamivudine, and nelfinavir. At baseline, constant CSF HIV-1 RNA concentrations were maintained by daily entry of at least 10(4) to 10(6) HIV-1 RNA copies into CSF. Change from baseline to day 5 ranged from -0.38 to -1.18 log(10) HIV-1 RNA copies/ml in CSF, and from -0.80 to -1.33 log(10) HIV-1 RNA copies/ml in plasma, with no correlation between CSF and plasma changes. There was no evidence of genotypic or phenotypic viral resistance in either CSF or plasma. With regard to pharmacokinetics, mean CSF-to-plasma area-under-the-curve (AUC) ratios were 38.9% for stavudine and 15.3% for lamivudine. Nelfinavir and its active M8 metabolite could not be accurately quantified in CSF, although plasma M8 peak level and AUC(0-8hr) correlated with CSF HIV-1 RNA decline. This study supports the utility of ultraintensive CSF sampling for studying HIV-1 pathogenesis and therapy in the CNS, and provides strong evidence that HIV-1 RNA in CSF arises, at least in part, from a source other than plasma.

Adult↗
PubMed2000

Earthquake potential along the northern hayward fault, california

The Hayward fault slips in large earthquakes and by aseismic creep observed along its surface trace. Dislocation models of the surface deformation adjacent to the Hayward fault measured with the global positioning system and interferometric synthetic aperture radar favor creep at approximately 7 millimeters per year to the bottom of the seismogenic zone along a approximately 20-kilometer-long northern fault segment. Microearthquakes with the same waveform repeatedly occur at 4- to 10-kilometer depths and indicate deep creep at 5 to 7 millimeters per year. The difference between current creep rates and the long-term slip rate of approximately 10 millimeters per year can be reconciled in a mechanical model of a freely slipping northern Hayward fault adjacent to the locked 1868 earthquake rupture, which broke the southern 40 to 50 kilometers of the fault. The potential for a major independent earthquake of the northern Hayward fault might be less than previously thought.

Journal Article↗
PubMed2000

NGF ligand alters NGF signaling via p75(NTR) and trkA.

Nerve growth factor (NGF) binds to two neurotrophin receptors: p75(NTR) and p140(Trk) (TrkA). Both receptors dimerize in response to NGF binding. TrkA homodimers and heteromers of TrkA and p75(NTR) promote cell survival whereas homodimers of p75(NTR) mediate apoptosis upon binding of NGF. The interaction between receptor and NGF can be inhibited either on the level of the ligand by altering NGF conformation so that NGF is no longer recognized by the receptor or on the level of the receptor by blocking the binding site of p75(NTR) or TrkA. The effect of altering NGF conformation on NGF signaling was investigated in two neuron-like cell lines: in human SK-N-MC cells that express only p75(NTR) and in rat PC12 cells that express both p75(NTR) and TrkA. In the present study we demonstrate that Ro 08-2750 binds to the NGF dimer thereby probably inducing a change in its conformation such that NGF cannot bind to p75(NTR) anymore. In SK-N-MC cells this leads to inhibition of NGF-induced programmed cell death. In PC12 cells enhanced signaling through TrkA was observed.

Animals↗
PubMed2000

Induction of gynogenesis in muskellunge with irradiated sperm of yellow perch proves diploid muskellunge male homogamety.

Diploid gynogenesis was induced in muskellunge Esox masquinongy using UV-irradiated muskellunge sperm as the first step in producing monosex females. In this approach, we have to rely on negative controls as an indirect reference for sperm genetic material destruction. In the first experiment, equal proportions of gynogenetic females and males were produced. Negative controls, UV-irradiated sperm without heat shock, yielded some normal hatching larvae, described as spontaneous diploids. In the second experiment, muskellunge eggs were activated using sperm from yellow perch. Because hybrids between these species are not viable, we produced unambiguous gynogens. When UV-irradiated yellow perch sperm was used to inseminate muskellunge eggs, haploids resulted (22.5% +/- 2.8% survival to the eyed stage). To produce diploid gynogens, a heat shock of 31 degrees C was applied to inseminated eggs 20 min after activation for a duration of 6 min. This process yielded several hundreds of gynogens for rearing. Several treatments of masculinizing hormone, 17alpha-methyltestosterone (MT), were carried out. Fish were dissected and gonads examined histologically for sex determination. Gynogens produced using yellow-perch sperm confirmed the presence of males in the control group, whereas the MT bath treatment (400 microg/liter) resulted in the production of fish with ovotestis. These results provide evidence for male homogamety in muskellunge and imply that a change of strategy is needed to produce monosex populations.

Animals↗
PubMed2000

Early detection of aspergillus infection after allogeneic stem cell transplantation by polymerase chain reaction screening.

Invasive aspergillosis (IA) has become a major cause of mortality in patients after allogeneic stem cell transplantation. To assess the potential of prospective polymerase chain reaction (PCR) screening for early diagnosis of IA, 84 recipients of an allogeneic stem cell transplant were analyzed with the investigators blinded to clinical and microbiologic data. Of 1193 blood samples analyzed, 169 (14.2%) were positive by PCR. In patients with newly diagnosed IA (n=7), PCR positivity preceded the first clinical signs by a median of 2 days (range, 1-23 days) and preceded clinical diagnosis of IA by a median of 9 days (range, 2-34 days). Pretransplantation IA (relative risk [RR], 2.37), acute graft-versus-host disease (RR, 2.75), and corticosteroid treatment (RR, 6.5) were associated with PCR positivity. The PCR assay revealed a sensitivity of 100% (95% confidence interval [CI], 48%-100%) and a specificity of 65% (95% CI, 53%-75%). None of the PCR-negative patients developed IA during the study period. Thus, prospective PCR screening allows for identification of patients at high risk for subsequent onset of IA.

Adolescent↗
PubMed2000

Ocular massage in a case of central retinal artery occlusion the successful treatment of a hitherto undescribed type of embolism.

BACKGROUND: The pathogenesis of central retinal artery occlusions (CRAO) varies, depending upon the underlying disease. An embolic origin of an occlusion often occurs. PATIENT AND METHODS: A 50-year-old man with an occlusion of the left internal carotid artery was examined because of a left central retinal artery occlusion. Fluorescein angiography revealed that in no blood vessel could any circulation of blood be demonstrated. The slight vascular filling with dye mainly came from collateral circulation at the disc. RESULTS: Ocular massage was carried out. After a delay of several minutes, the vessels of the fundus became increasingly filled with blood. The patient noticed continuing recovery in the vision of his left eye. During fluorescein angiography, carried out one day later, white embolic clots appeared in the arteries of the papilla, some of them moving with the velocity of the blood flow through the retinal vessels and reaching the periphery of the retina and immediately disappearing. Others moved more slowly. This was seen repeatedly over several minutes. CONCLUSIONS: In this patient we have recorded in a fluorescein angiogram bright boluses visible in the blood of the retinal arteries. We suggest that conglomerations of blood cells can also cause an obstruction of blood flow. The observation of this kind of bright clots (boluses) visible in the blood of the retinal arteries we did not find described in the literature. In such a situation ocular massage is extremely helpful. Therefore, ocular massage should be carried out in every patient with CRAO.

Arteriosclerosis↗
PubMed2000

Early detection of preeclampsia by determination of platelet aggregability.

Preeclampsia is still a leading cause of maternal and fetal morbidity and mortality. There is evidence for the involvement of platelets. Therefore, we investigated the suitability of corrected whole blood impedance aggregometry as an early predictor of preeclampsia in 71 consecutive, high-risk pregnancies. According to the occurrence of preeclampsia, defined postpartum by an independent investigator, and the stage of pregnancy (early and late, cutoff: 25 weeks of gestation), four study groups were defined. Platelet aggregation data were corrected for the influence of hematocrit and platelet count by a special purpose software package. Women developing preeclampsia showed significantly higher platelet aggregation response compared to controls in early and late pregnancy. In early pregnancy, all women developing preeclampsia had aggregation responses to collagen higher than the highest responses among the controls. Hence, this test had a 100% positive predictive value of subsequent preeclampsia. Despite being significantly increased, platelet aggregability was of minor predictive value in late pregnancy. We conclude that preeclampsia is accompanied by exaggerated platelet aggregability, particularly perceptible early in the course of pregnancy. We propose collagen-induced whole blood platelet aggregation with correction for the influence of hematocrit and platelet count for early detection of preeclampsia.

Adenosine Diphosphate↗
PubMed2000

Long-term results of laser treatment for retinal angiomatosis in von Hippel-Lindau disease.

PURPOSE: In von Hippel-Lindau disease (VHL), retinal detachment is often a real threat if the retinal angiomas are left untreated. The aim of this trial was to diagnose and treat capillary angiomas early at an asymptomatic stage. METHODS: Since 1983, we have investigated patients with key lesions and those who are at risk for VHL in a multidisciplinary study. Classical retinal angiomas and microangiomas were treated with the Argon laser. Checks during a follow-up of 15 years have provided us with long-term results. RESULTS: We detected 189 retinal angiomas in 97 eyes of 69 patients (105 classical angiomas, including 19 fibrotic angiomas in 15 eyes, 84 microangiomas). During the study, 20 patients (twenty-one symptomatic eyes) entered the study already with a visual impairment. Sixty asymptomatic eyes from 49 patients with a total of 108 retinal angiomas (55 microangiomas and 53 classical angiomas) were treated by us with photocoagulation. Nineteen asymptomatic eyes with angiomas of fibrotic type were observed only. During a mean follow-up of 5.1 years (range: 0.25 - 15; SD: 3.88) observed after treatment, no deterioration of vision occurred in 37 patients treated with photocoagulation. Regular controls showed 5 relapsing angiomas and 9 new angiomas which were successfully coagulated again. New angiomas occurred in those eyes with several angiomas as a predisposition. Patients with a tendency to multiple angiomas need to be seen more frequently because these eyes have a high risk of becoming blind, even in already coagulated angiomas. CONCLUSION: Laser treatment was successful. Early ophthalmological examination of patients with retinal angiomatosis is a great challenge, since these lesions can only be successfully treated at an early stage. Treatment is then effective and safe, but long-term follow-up is necessary. New angiomas occurred in those eyes with several angiomas as a predisposition.

Adolescent↗
PubMed2000

The difference between electroacupuncture only and electroacupuncture with manipulation on analgesia in rats.

Plain acupuncture uses manipulation (rotation or varying the depth of insertion of the needle) to increase its effect. However, in commonly used electroacupunture (EA), variable manipulations have not been used. This study was performed to investigate the possibility of an increase in analgesic effect by adding manipulation to EA. The pain index used was the Tail-Flick latency (TFL) of the rat, which was lightly anesthetized with thiopental sodium (intraperitoneally). Four types of manipulation were used. Rotation and varying the depth of the needle (RN and VN) was employed using two different types of manipulation during each 20 min stimulation of EA. Each manipulation persisted for 1 min out of every 5 min (long - duration and long - interval: LDLI) or 12 s every 1 min (short - duration and short interval: SDSI). EA produced an increase in TFL; peak value was 49.7+/-12.2% of the pre - EA and occurred immediately after cessation of 20 min of EA stimulation. Performing RN or VN combined with EA also increased TFL more than just EA and a greater peak increase in TFL was observed with a SDSI - RN and SDSI - VN as compared to a LDLI - RN and LDLI - VN (77.5+/-13.8, 79.2+/-19.8 and 67.3+/-14.0%, 65.6+/-23.7% of the pre - EA, respectively). These results indicate that manipulation combined with EA produces a more potent antinociception than when only EA is applied.

Acupuncture Analgesia↗
PubMed2000

Increased activity of the hypothalamic-pituitary-adrenal axis of rats exposed to alcohol in utero: role of altered pituitary and hypothalamic function.

Prenatal exposure to ethanol (E) enhances the offspring's ACTH and corticosterone responses to stressors. Here, we determined the role of increased pituitary responsiveness and/or PVN neuronal activity in this phenomenon. Pregnant rats were exposed to E vapors during days 7-18 of gestation, and we compared the responses of their 55- to 60-day-old offspring (E rats) to those of control (C) dams. PVN mRNA levels of the immediate early genes (IEGs) c-fos and NGFI-B, which were low under basal conditions in all groups, showed a peak response 15 min after shocks and 45 min after LPS treatment. These responses were significantly enhanced in E, compared to C offspring of both genders. CRF, but not VP hnRNA levels were also significantly higher in the PVN of shocked E offspring. Resting median eminence content of CRF and VP, and pituitary responsiveness to CRF, were unchanged, while responsiveness to VP was marginally increased in females. These results indicate that prenatal alcohol selectively augments the neuronal activity of hypothalamic CRF perikarya.

Adrenocorticotropic Hormone↗