Biomedical subjects

F Richter

Publications and source records attributed to F Richter.

At least 19 recordsLinked to original sources

PubMed2006

Effect of sympathetic and parasympathetic mediators on the release of calcitonin gene-related peptide and prostaglandin E from rat dura mater, in vitro.

Although not without controversy, an influence of the autonomic nervous system in headache is a matter for current debate. A possible contact site of autonomic and sensory nerves is the dura mater, where they form a dense network accompanying blood vessels. We investigated interactions between autonomic and nociceptive fibres by measuring release of calcitonin gene-related peptide (CGRP) and prostaglandin E2 (PGE2) from the dura mater, in vitro. The parasympathomimetic agent carbachol did not change basal release of CGRP or PGE2, whereas it diminished release induced by a mixture of inflammatory mediators. Norepinephrine did not change induced release of CGRP or PGE2, nor basal release of CGRP. However, basal release of PGE2 was enhanced by norepinephrine, and this enhancement was reduced by serotonin through 5-HT(1D) receptors. We conclude that sympathetic transmitters may control nociceptor sensitivity via increased basal PGE2 levels, a possible mechanism to facilitate headache generation. Parasympathetic transmitters may reduce enhanced nociceptor activity.

Animals↗

PubMed2004

Is there a close relationship between changes in amplitudes of distortion product otoacoustic emissions and hair cell damage after exposure to realistic industrial noise in guinea pigs?

In long-term experiments in awake guinea pigs (n = 12), distortion product otoacoustic emissions (DPOAEs) at various frequencies were measured repeatedly over 6-8 months. About 9 weeks after the first measurement, the animals were exposed to industrial noise (car industry, maximal intensity about 110 dB SPL) for 2 h. The amplitudes of DPOAE were measured prior to noise exposure and 10 min, 70 min, 1 day and 2 days after the noise exposure and then once every week. Three to four months after noise exposure, the animals were killed, and the cochleae were prepared for scanning electron microscopy. The row of inner hair cells (IHCs) was complete in all animals, while the rows of outer hair cells (OHCs) showed a considerable hair cell loss in some of the animals without a correlation to the change in amplitudes of DPOAE. However, a closer relationship between the decline of amplitudes of DPOAE and the number of missing and changed OHCs (fused stereocilia bundles, missing tip links) could be established. The number of lost OHC does not reflect the decline in DPOAE in all cases. This discrepancy must be considered when the degree of hearing loss needs to be established from changed DPOAE.

Animals↗

PubMed2004

Multiphasic helical CT diagnosis of early medullary and papillary necrosis.

PURPOSE: The feasibility of identifying early manifestations of renal papillary necrosis (RPN) and medullary necrosis (RMN) on multiphasic helical CT, leading to prompt treatment for the causative conditions, and its impact on reducing the incidence of late-stage RML and RPN, was investigated. PATIENTS AND METHODS: Sixty-eight patients (35 male, 33 female) aged 19 to 88 years were examined by multiphasic helical CT for complaints of microscopic hematuria (N=49), macroscopic hematuria (N=2), bacteriuria (N=45), pyuria (N=10), fever (N=15), and flank pain (N=27). Preenhancement, arterial corticomedullary, parenchymal, and excretory phase scans generated 1.25 to 7-mm-thick slices. Follow-up CTs were performed at 1 month (N=62) and 3 months (N=58). RESULTS: While the attenuation coefficients of areas suspect for RMN and RPN were similar on preenhancement CT, they differed substantially on the arterial corticomedullary phase (lesions 55 HU mean; normal medulla 120 HU mean) and parenchymal phase (lesions 58 HU mean, normal medulla 210 HU mean). Investigation for predisposing conditions identified diabetes in 18 patients, upper urinary-tract infections in 48, sickle-cell disease or trait in 17, urinary obstruction in 7, and cirrhosis of the liver in 1. On follow-up examinations, enhancement had normalized in 26 compromised areas of 14 patients at 1 month, and 47 areas (23 patients) at 3 months, remained stationary in 28 patients at 1 month and 9 at 3 months, and progressed in 20 at 1 and 26 at 3 months (P<0.001; Fisher's exact test). Patients (N=35) treated for underlying conditions causing ischemia showed reperfusion in 12 cases at 1 month and 20 at 3 months, while of the untreated patients (N=10), none showed reperfusion, and all lesions increased in size. CONCLUSIONS: Multiphasic helical CT is recommended for identification of RMN and RPN at a stage when effective treatment of underlying causative conditions can arrest or reverse the process of devascularization and prevent loss of medullary tissue.

Adult↗

PubMed2004

Multiphasic helical CT criteria for differentiation of recurrent neoplasm and desmoplastic reaction after laparoscopic resection of renal mass lesions.

BACKGROUND AND PURPOSE: Differentiation of recurrent neoplasm and desmoplastic reaction following laparoscopic resection of renal mass lesions poses a problem. The usefulness of multiphasic helical CT-generated criteria based on enhancement and morphologic characteristics was investigated. PATIENTS AND METHODS: The findings in 5 female and 12 male patients aged 29 to 68 years having renal-cell carcinoma (11-38 mm; N = 15) or solitary angiomyolipomas (N = 2) treated by laparoscopic resection (N = 15) or open segmental surgery (N = 2) were analyzed. Multiphasic helical CT was performed in the preenhancement, arterial corticomedullary, parenchymal, and excretory phases generating 2.5- to 7-mm slices. RESULTS: Both recurrent neoplasms showed median postcontrast enhancement of 119 HU in the arterial corticomedullary phase; the median enhancement of desmoplastic masses was 48 HU. In the parenchymal and excretory phase, recurrent neoplasms showed progressive loss of enhancement, whereas desmoplastic lesions sustained enhancement at about the same level. Recurrent neoplasms presented a defined mass with characteristic spiculation, whereas desmoplastic reaction was characterized by an ill-defined mass with spidery projections extending to abutting fat and residual fascial planes. On 2- to 3-month follow-up scans, recurrent neoplasms showed progressive increases in size and desmoplastic reaction a sharp decrease. CONCLUSION: Enhancement of the mass at the operative site on arterial corticomedullary-phase CT to >90 HU strongly suggests recurrent renal-cell carcinoma, while progressive decrease in size on 1- to 3-month follow-up CT suggests a desmoplastic reaction.

Adult↗

PubMed2004

Multiphasic helical computerized tomography for the assessment of microscopic hematuria: a prospective study.

PURPOSE: We evaluated multiphasic helical computed tomography for the detection and characterization of lesions responsible for hematuria not diagnosed on prior urological surveillance studies. MATERIALS AND METHODS: A total of 393 men and 207 women with recurrent microscopic hematuria but negative urological surveillance studies were examined at 4 participating institutions by multiphasic helical computerized tomography, consisting of pre-enhancement, arterial corticomedullary, parenchymal and excretory phase sequences generating 2 to 5 mm slices through the kidney and lower pelvis. RESULTS: The cause of microscopic hematuria was established in 256 of 600 patients with prior negative urological surveillance examinations with 0.91 sensitivity and 0.94 specificity. The diagnosis was correct in all subsequently proven cases of calculous and renal vascular disease. A total of 67 of 70 inflammatory kidney lesions, 24 of 25 renal neoplasms, 15 of 16 bladder neoplasms, 27 of 35 inflammatory bladder conditions and 21 of 23 ureteral lesions were also correctly diagnosed. The diagnosis of renal medullary and papillary necrosis, and neoplastic lesions of the kidney and bladder allowed the early institution of medical therapy or appropriate surgery. CONCLUSIONS: Multiphasic helical computerized tomography diagnosed lesions responsible for microhematuria in 42.6% of 600 patients with negative urological surveillance examinations. This relatively low cost and low co-morbidity examination is advocated for patients with negative urological surveillance examinations or even as a first examination.

Adult↗

PubMed2004

Effects of N-, P/Q- and L-type calcium channel blockers on nociceptive neurones of the trigeminal nucleus with input from the dura.

In anaesthetized rats, extracellular recordings were made from neurones of the spinal trigeminal nucleus, involved in the processing of nociceptive input from the dura. Blockers of voltage-gated calcium channels (VGCCs) were administered topically to the exposed brainstem. Blockade of N-type (CaV2.2) channels reduced spontaneous activity and responses of the neurones to cold and chemical stimuli applied to the dura, suggesting that N-type channels regulate excitatory synaptic activation. Blockade of L-type (CaV1) channels enhanced spontaneous discharges of the neurones. Blockade of P/Q-type (CaV2.1) channels slightly decreased responses to chemical and cold stimuli but markedly increased spontaneous activity, an effect which was absent during concomitant application of GABA to the brainstem. The data suggest that P/Q-type VGCCs regulate a tonic synaptic inhibitory control of the brainstem neurones. The risk of migraine by genetic modifications of P/Q-type channels may thus be sought in disturbed inhibition in the network that processes nociceptive dura input.

Action Potentials↗

PubMed2003

A functionalized THz sensor for marker-free DNA analysis.

We report on a novel resonant THz sensor for the label-free analysis of DNA molecules. The sensor allows the direct detection of DNA-probe molecules at functionalized electrodes via hybridization. Subsequent time resolved photoconductive sampling of the THz transmission identifies the binding state between probe and target DNA. Integrating neighbouring sensors on a chip, this technique can be extended to a parallel analysis of multiple DNA sequences. A clearly readable sensor response is obtained with less then 40 fmol of 20-mer single-stranded DNA molecules, indicating at least a sevenfold sensitivity increase compared to previous approaches.

Biosensing Techniques↗

PubMed2003

[Improvement of hemostasis in laparoscopic and open partial nephrectomy with gelatin thrombin matrix (FloSeal)].

Long-term follow-up studies have demonstrated that effective local tumor control and long-term tumor-free progression rates can be achieved by nephron-sparing surgery. However, hemostasis is a major issue and the lack of effective means of hemostasis has limited a wider use of the laparoscopic approach to nephron-sparing surgery. Between January 2001 and August 2002, a total of 36 patients with renal cell carcinomas were treated by partial nephrectomies using a two-component tissue sealant (FloSeal). The median age was 55.2 years (range: 34-71 years). Follow-up time was 1-18 months (median: 5.5 months). The tumor diameter ranged from 2 to 5 cm (median: 2.9 cm). Open retroperitoneal surgery was performed in 17 cases and laparoscopic partial nephrectomy in 19 cases. The two-component tissue sealant (consisting of a gelatin matrix with granular and thrombin components) was applied after resection of the tumor and before perfusion of the kidney. The following parameters were recorded: (1) time until complete hemostasis was achieved, (2) decrease in postoperative hemoglobin level, (3) postoperative bleeding, and (4) presence or absence of a perirenal hematoma 24 h and 10 days postoperatively by ultrasound. After application of the tissue sealant for 1-2 min to the moist resection site, hemostasis was immediate in all cases. During the laparoscopic partial nephrectomies, a laparoscopic applicator was used that avoided wasting the tissue sealant within the dead space of the instrument. When reperfusion of the kidney was established, hemostasis was maintained. The decrease in postoperative hemoglobin level ranged from 0.3 to 1.2 points (median: 0.8 points). None of the patients required blood transfusions. There were no cases of postoperative bleeding. An ultrasound examination 24 h and 10 days postoperatively demonstrated the absence of a significant perirenal hematoma. The two-component tissue sealant FloSeal provided immediate and durable hemostasis in open and laparoscopic partial nephrectomies. The tissue sealant may provide a tool to expand the possibilities of laparoscopic nephron-sparing surgery.

Adult↗

PubMed2003

Detection of medullary and papillary necrosis at an early stage by multiphasic helical computerized tomography.

PURPOSE: Multiphasic helical computerized tomography (CT) is advocated to identify early manifestations of papillary and medullary necrosis based on decreased enhancement of circumscribed areas in the medullary pyramid. At this stage the devascularizing process can be reversed if causative conditions such as infections or diabetes mellitus are effectively treated. MATERIALS AND METHODS: Multiphasic helical CTs were performed in 31 male and 26 female patients with complaints of microscopic hematuria (41), macroscopic hematuria (2), bacteriuria (39) and pyuria (9). Pre-enhancement, arterial, early corticomedullary, parenchymal and excretory phase helical CTs generated 1.25 to 5 mm. thick slices. Followup examination included multiphasic helical CT at 1 and 3 months, and excretory urography for some patients at 3 months. RESULTS: Bacteriuria was identified as the probable cause of medullary and papillary necrosis in 39 patients, of whom 28 were treated with effective antibiotic therapy, resulting in normalization and re-perfusion of the initial lesion in 16, no change in 5 and progressive disease in 7 at 3-month followup. Of 8 lesions not treated with specific antibiotic therapy 4 progressed and 4 remained unchanged. CONCLUSIONS: Multiphasic helical CT unlike the excretory urogram can identify medullary and papillary necrosis at an early stage when effective treatment of the underlying cause can reverse the process of devascularization and prevent sloughing of medullary tissues.

Adult↗

PubMed2002

[Spirometry, pulse oximetry, brochospasmolytic test. The pillars of COPD diagnosis].

In addition to case history and clinical examination, the basic diagnostic work-up of chronic obstructive pulmonary disease comprises in particular lung function testing by means of spirometry. In the event of an uncertain diagnosis, or in a search for underlying causes, an additional EKG, chest X-ray and bronchospasmolytic testing to determine the reversibility of the airways obstruction are employed. In COPD patients younger than 50, as well as in those with pulmonary edema largely confined to the basal fields, determination of the alpha-1-antitrypsin should be carried out. In the case of an exacerbation of the clinical presentation, the sputum should be cultured to determine the possible presence of pathogenic bacteria. Recurrent exacerbations or a rapid worsening of dyspnea necessitate hospitalization.

Adrenergic beta-Agonists↗

PubMed2002

Changes in extracellular space volume and geometry induced by cortical spreading depression in immature and adult rats.

Changes in extracellular space (ECS) diffusion parameters, DC potentials and extracellular potassium concentration were studied during single and repeated cortical spreading depressions (SD) in 13-15 (P13-15), 21 (P21) and 90-day-old (adult) Wistar rats. The real-time iontophoretic method using tetramethylammonium (TMA+)-selective microelectrodes was employed to measure three ECS parameters in the somatosensory cortex: the ECS volume fraction alpha (alpha = ECS volume/total tissue volume), ECS tortuosity lambda (increase in diffusion path length) and the nonspecific TMA+ uptake k'. SD was elicited by needle prick. SD was significantly longer at P13-15 than at P21 and in adults. During SD, alpha in all age groups decreased from 0.21-0.23 to 0.05-0.09; lambda increased from 1.55-1.65 to 1.95-2.07. Ten minutes after SD, alpha (in adults) and lambda (all age groups) increased compared to controls. This increase persisted even 1 hour after SD. When SD was repeated at 1 hour intervals, both alpha and lambda showed a gradual cumulative increase with SD repetition. Our study also shows that cortical SD is, as early as P13, accompanied by severe ECS shrinkage and increased diffusion path length (tortuosity) with values similar to adults, followed by a long-lasting increase in ECS volume and tortuosity when compared to pre-SD values.

Aging↗

PubMed2001

Miscibility gap in fluid dimyristoylphosphatidylcholine:cholesterol as "seen" by x rays.

A binary mixture of dimyristoylphosphatidylcholine (DMPC) and cholesterol displays a fluid miscibility gap under excess water conditions. Effects due to the imperfect miscibility of the two amphiphiles are studied near to and far from thermodynamic equilibrium by time-resolved small angle x-ray diffraction. The experiment discloses that this mixture phase separates when leaving the miscibility gap upon heating, a transition that is not included in current phase diagrams. This transition appears to be reversible and shows a temperature hysteresis of only a few degrees. We suggest a model in which the transition is driven with increasing temperature by a movement of the cholesterol away from the hydrophilic-hydrophobic interface toward the hydrophobic core of the bilayer.

Biophysical Phenomena↗

PubMed2001

Management of prepubertal varicoceles-results of a questionnaire study among pediatric urologists and urologists with infertility training.

OBJECTIVES: Varicoceles are a common condition affecting male fertility seen by urologists. However, prepubertal varicoceles are much less common and their management is controversial. We designed a questionnaire to assess the practice patterns among urologists (pediatric urologists/urologists with infertility training) with regard to prepubertal varicocele management. METHODS: A 15-point questionnaire pertaining to management issues of prepubertal varicoceles was sent to 150 pediatric urologists and 150 urologists with infertility training. Two clinical scenarios referring to treatment algorithms of prepubertal varicoceles were included. RESULTS: Of the 300 questionnaires mailed, 174 urologists (58%) responded. Seventy-five of the respondents were urologists with an interest in infertility, and 99 were pediatric urologists. Of the 174 respondents, 86.2% treated prepubertal varicoceles and 13.8% referred patients to interventional radiologists for embolization. The ratio of varicocelectomy to expectant management was about equal between urologists with infertility training and pediatric urologists (46% versus 54%). A difference in testicular size was the most common indication for varicocelectomy (80.5%), followed by pain (51.1%) and potential fertility problems (24.7%). About one third of all urologists would perform varicocelectomy on patients of any age and seven (4%) would not operate before puberty. In 136 responses (78.2%), follow-up information was not available. Among the 35 respondents with follow-up information (21.8%), 21 reported infertility occurring after varicocelectomy and 16 after expectant management. If varicocelectomy was performed, most urologists (47.2%) used magnification loupes, 29.3% used microscopes, and 29% used no magnification. The preferred approach was inguinal (Ivanissevich) in 35.6% followed by subinguinal in 30%; 21% performed retroperitoneal varicocelectomy (Palomo) and 9.8% used a laparoscopic approach. Of the 300 complications reported, postoperative hydroceles were the most common (40.4%), followed by recurrence (20.8%) and hematomas (17.4%). CONCLUSIONS: The management of prepubertal varicoceles is controversial among different urologic subspecialties (pediatric urology/infertility). Differences include indications, timing, and techniques used for varicocelectomy. Accurate follow-up information for children with prepubertal varicoceles is rare. A prospective randomized study comparing varicocelectomy versus expectant management of prepubertal varicoceles is needed to assess the outcomes and define uniform treatment criteria.

Adolescent↗

PubMed2001

Verrucous carcinoma of the renal pelvis.

We report a case of a verrucous carcinoma of the renal pelvis after a long history of a renal pelvis stone. Only 1 case of verrucous carcinoma of the renal pelvis has been previously reported, and ours is the first case not associated with a horseshoe kidney.

Carcinoma, Verrucous↗

PubMed2001

Are we ordering too many PSA tests? Prostate cancer diagnosis and PSA screening patterns for a single Veterans Affairs Medical Center.

BACKGROUND: Limits on the frequency of PSA testing and an endpoint for the age of the screened population have not been established. The numbers of performed serum PSA tests, cost evolution, and utilization patterns by various subspecialties in one medical center were analyzed to gain insight into trends in screening for early detection of prostate cancer and gather information about the appropriate use of PSA testing. METHOD: Computerized records were reviewed for numbers of PSA tests obtained, prostate biopsies performed, and prostate cancer cases diagnosed in the VA NJ-Health Care System from 1996 to 1998. In addition, PSA tests performed during two representative weeks in 1996 and 1997 were analyzed to evaluate a smaller cohort of patients with regard to age, consequences of the test results in their management, and subspecialties ordering the tests. RESULTS: PSA testing increased steadily between 1992 and 1998, with the most significant change (152% increase) between 1997 (9,410 tests) and 1998 (23,684). Prostate cancer diagnoses by biopsy were 164/434 (37.8%) in 1997 and 195/507 (38.5%) in 1998. For the 14,274 additional PSA tests obtained in 1998, 31 more prostate cancers were diagnosed. Prostate cancer diagnoses per PSA tests were 164/9,410 (1.8%) in 1997 and 195/23,684 (0.8%) in 1998. Primary care providers ordered 61% of the PSA tests. CONCLUSIONS: Most PSA tests at this institution were ordered by general practitioners, and the number of PSA tests ordered for men over 75 was high. The dramatic increase between 1997 and 1998 was not accompanied by a similar rise in the diagnosis of prostate cancer, raising the possibility of indiscriminate PSA testing or unnecessary repetition of testing. Guidelines for prostate cancer screening and continued PSA testing in the geriatric population may need further clarification.

Aged↗

PubMed2001

Sclerosing cholangitis and liver cirrhosis after extrabiliary infections: report on three cases.

OBJECTIVE: To describe three unusual cases of sclerosing cholangitis after severe extrahepatic/extrabiliary bacterial infections. DESIGN: Case report, clinical. SETTING: Tertiary care intensive care unit (ICU). PATIENTS: Three patients admitted to the ICU with infections from Gram-positive bacteria followed by sclerosing cholangitis and secondary biliary cirrhosis. MAIN RESULTS: Three unusual cases of persisting cholestasis that occurred after bacterial infections originating from extrahepatic/extrabiliary foci are described. Endoscopic retrograde cholangiopancreatography and magnetic resonance cholangiopancreatography revealed multiple strictures of the intrahepatic bile ducts as a sign of sclerosing cholangitis. All patients progressed to biliary cirrhosis within months after the onset of cholestasis. CONCLUSION: Infection-associated cholestasis is usually a functional disorder and subsides after effective treatment of the underlying inflammatory focus. In rare cases, however, extrahepatic/extrabiliary infections may lead to sclerosing cholangitis and secondary biliary cirrhosis via unknown mechanisms.

Adult↗

PubMed2001

Butyrate and propionate downregulate ERK phosphorylation in HT-29 colon carcinoma cells prior to differentiation.

We have characterized the effects of different short-chain fatty acids (SCFAs) on cell growth and differentiation as well as the phosphorylation state of ERK1 and 2 in the human colon adenocarcinoma cell line HT-29. Of the five SCFAs tested, only butyrate and propionate impaired cellular proliferation. Moreover, butyrate and propionate specifically resulted in a decrease in ERK1 and 2 phosphorylation at 3 and 6 hours post-treatment, suggesting a correlation between the ability of these SCFAs to inhibit cellular proliferation and decrease ERK phosphorylation. Notably, the decrease in ERK phosphorylation was observed prior to the induction of the differentiation markers alkaline phosphatase (AP) and carcinoembryonic antigen (CEA) by butyrate and propionate from days 6 to 18 post-treatment. In the case of butyrate- and propionate-induced differentiation, ERK phosphorylation is a marker and may play a role in the proliferation and/or differentiation states of this cell line.

Alkaline Phosphatase↗

PubMed2001

Is there a correlation between spreading depression, neurogenic inflammation, and nociception that might cause migraine headache?

The time course of propagation of scotoma and blood flow changes during migraine aura parallels the phenomenon of cortical spreading depression (CSD). It was proposed that CSD generates a sterile neurogenic inflammation in the meninges, which may then lead to the activation or sensitization of nociceptors, thus generating headache. We performed rat experiments in which the effect of CSD on plasma extravasation in the dura mater and on neuronal activity in deep laminae of the trigeminal nucleus was assessed in vivo. CSD did not alter dural plasma extravasation measured by means of bovine serum albumin-coupled flourescein (n = 17 rats) compared to the CSD-free contralateral side. In an in vitro model, the application of KCl to the dura at concentrations extracellularly found during CSD did not alter the release of calcitonin gene-related peptide and prostaglandin E2 from the dura. In 33 rats, neither single CSDs nor a series of CSDs altered ongoing neuronal activity or mechanical and/or thermal sensitivity of the deeply located neurons to stimulation of their receptive fields in the dura mater. These results are at variance with data that showed increased c-Fos labeling in superficial laminae of the trigeminal nucleus following CSD. They do not suggest that CSD initiates migraine headache via neurogenic inflammation.

Animals↗