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Biomedical subjects

F Richter

Publications and source records attributed to F Richter.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Diagnosis and differential diagnosis of bronchial asthma].

Asthma and COPD (chronic obstructive pulmonary disease) are the most important obstructive pulmonary diseases. Patient's history and physical evaluation give major hints of the underlying disease. Further diagnostic measures comprise lung function analysis including spirometry, plethysmography and--in severe cases--blood gas analysis. Bronchial hyperreactivity may be quantified with an unspecific inhalative provocation test. In many cases allergic diseases are accompanied by asthma. Thus, allergy tests--particularly skin prick tests--have to be carried out. To further define an underlying allergy, in some cases even specific inhalative provocation tests have to be performed. X-ray of the thorax and other imaging techniques, detailed blood analysis, further diagnosis of the upper respiratory tract and the cardiac system may have to be carried out a) to quantify the effects of a severe form of asthma or COPD on other organs, and b) for differential diagnostic examinations.

Asthma↗
PubMed2000

The effect of impulse noise exposure on distortion product otoacoustic emissions in the awake guinea pig.

Distortion product otoacoustic emissions (DPOAE) are a sensitive detector of outer hair cell (OHC) function and were monitored in awake guinea pigs before and after impulse noise damaging the cochlea (peak intensity 153 dB SPL, rise time < 0.1 ms). Animals had stable DPOAE levels before noise exposure. In the first hours after noise exposure DPOAE levels were reduced significantly. Three different patterns of recovery of DPOAE were seen in the post-exposure period:restitution exceeding controls, partial recovery and no recovery. In general, DPOAE levels declined and types of recovery closely corresponded to changes in amplitudes of cochlear microphonics after noise exposure. These data suggest that the monitoring of DPOAE is a suitable method for diagnosing impaired OHC function.

Animals↗
PubMed2000

Dimyristoylphosphatidylcholine/C16:0-ceramide binary liposomes studied by differential scanning calorimetry and wide- and small-angle x-ray scattering.

Ceramide has recently been established as a central messenger in the signaling cascades controlling cell behavior. Physicochemical studies have revealed a strong tendency of this lipid toward phase separation in mixtures with phosphatidylcholines. The thermal phase behavior and structure of fully hydrated binary membranes composed of dimyristoylphosphatidylcholine (DMPC) and N-palmitoyl-ceramide (C16:0-ceramide, up to a mole fraction X(cer) = 0.35) were resolved in further detail by high-sensitivity differential scanning calorimetry (DSC) and x-ray diffraction. Both methods reveal very strong hysteresis in the thermal phase behavior of ceramide-containing membranes. A partial phase diagram was constructed based on results from a combination of these two methods. DSC heating scans show that with increased X(cer) the pretransition temperature T(p) first increases, whereafter at X(cer) > 0.06 it can no longer be resolved. The main transition enthalpy DeltaH remains practically unaltered while its width increases significantly, and the upper phase boundary temperature of the mixture shifts to approximately 63 degrees C at X(cer) = 0.30. Upon cooling, profound phase separation is evident, and for all of the studied compositions there is an endotherm in the region close to the T(m) for DMPC. At X(cer) >/= 0.03 a second endotherm is evident at higher temperatures, starting at 32.1 degrees C and reaching 54.6 degrees C at X(cer) = 0.30. X-ray small-angle reflection heating scans reveal a lamellar phase within the temperature range of 15-60 degrees C, regardless of composition. The pretransition is observed up to X(cer) < 0.18, together with an increase in T(p). In the gel phase the lamellar repeat distance d increases from approximately 61 A at X(cer) = 0. 03, to 67 A at X(cer) = 0.35. In the fluid phase increasing X(cer) from 0.06 to 0.35 augments d from 61 A to 64 A. An L(beta')/L(alpha) (ripple/fluid) phase coexistence region is observed at high temperatures (from 31 to 56.5 degrees C) when X(cer) > 0.03. With cooling from temperatures above 50 degrees C we observe a slow increase in d as the coexistence region is entered. A sudden solidification into a metastable, modulated gel phase with high d values is observed for all compositions at approximately 24 degrees C. The anomalous swelling for up to X(cer) = 0.30 in the transition region is interpreted as an indication of bilayer softening and thermally reduced bending rigidity.

Biophysical Phenomena↗
PubMed2000

Endourologic management of benign ureteral strictures with and without compromised vascular supply.

OBJECTIVES: To retrospectively assess the efficacy of balloon dilation, endopyelotomy/ureterotomy, and stenting alone in the management of benign ureteral strictures with intact or compromised vascular supply. METHODS: One hundred fourteen patients with benign ureteral strictures were assessed after at least a 2-year follow-up (range 2 to 16 years, mean 6.3). Balloon dilation was performed in 81, endopyelotomy/ureterotomy with temporary stenting in 27, and ureteral stenting alone in 6 patients. Ureteral strictures were divided into strictures with intact or with compromised vascular supply. RESULTS: Balloon dilation was successful in short ureteral strictures with intact vascular supply in 33 of 37 (89.2%), but only in 3 of 8 (37.5%) long ureteral strictures and in 1 of 2 (50%) recurrent ureteropelvic junction strictures. Balloon dilation was less successful when the vascular supply was compromised in 2 (40%) of 5 short strictures, 1 (16.7%) of 6 long strictures, and 2 (33.3%) of 6 recurrent ureteropelvic junction strictures. Endopyelotomy/ureterotomy was successful in 17 (89.5%) of 19 strictures with compromised vascular supply. CONCLUSIONS: Balloon dilation is recommended for management of short strictures with intact vascular supply. Endoureterotomy with stenting is recommended for all long ureteral strictures, for ureteropelvic junction stenoses, and for short ureteral strictures with compromised vascular supply and benign underlying etiology.

Adult↗
PubMed2000

Accuracy of diagnosis by guided biopsy of renal mass lesions classified indeterminate by imaging studies.

OBJECTIVES: To define the accuracy, safety, and impact of percutaneous biopsies of indeterminate mass lesions as an additional diagnostic tool. The vast majority of renal mass lesions are routinely diagnosed by radiographic features alone. However, with the increased use of computed tomography scanning and ultrasound, many smaller renal masses, which are "indeterminate" (refractory to categorization on the basis of imaging alone), are now being discovered. METHODS: We retrospectively reviewed 583 patients (364 male and 219 female) with indeterminate renal mass lesions diagnosed by imaging studies that were further investigated by percutaneous biopsy. Patients were followed up for at least 5 years if the biopsy result demonstrated a benign lesion, or they underwent surgical exploration if the biopsy result demonstrated a malignancy. Biopsy or aspiration material was assessed by histopathologic and cytologic evaluation and, when appropriate, with biochemistry, Gram stain, culture, and sensitivity. The biopsy site was localized by computed tomography, ultrasound, or fluoroscopy. RESULTS: Five hundred eighty-three patients with indeterminate renal mass lesions (representing 7.2% of all renal masses diagnosed from 1967 through 1996) were diagnosed by imaging studies complemented by guided biopsy. Sixty-six patients were lost to follow-up, leaving 517 patients who were analyzed. In 393 cases (76%), the imaging-guided biopsy provided a definitive diagnosis. The incidence of false diagnoses was 1.2% (7 biopsies). In 124 of the cases (21%), imaging-guided biopsy was unable to determine the etiology of the lesion with acceptable confidence; of these, 21 biopsies did not provide enough material to establish the diagnosis (16.9%). CONCLUSIONS: Overall, percutaneous biopsy of the kidney has proved to be a safe and accurate diagnostic procedure, with impact on the management of cystic or solid renal lesions.

Adolescent↗
PubMed2000

Effects of industrial noise exposure on distortion product otoacoustic emissions (DPOAEs) and hair cell loss of the cochlea--long term experiments in awake guinea pigs.

Distortion product otoacoustic emissions (DPOAEs), a sensitive detector of outer hair cell (OHC) function, cochlear microphonics (CM), and hair cell loss have been monitored in 12 awake guinea pigs before and after 2 h exposure to specific, played-back industrial noise (105 dB SPL maximal intensity). All animals had stable DPOAE levels before noise exposure. In the first hours after noise exposure DPOAE levels were reduced significantly. In about 70% a partial recovery of the DPOAEs was found within 4 months after noise exposure. In 16% of the investigated ears no recovery of DPOAEs was observed. However, in a few ears increased DPOAEs were observed after noise exposure. Exposure to industrial noise caused both morphological changes in the middle turns of the cochlea and electrophysiological changes in the middle frequency range. A close correlation existed between reduced DPOAE levels, loss in CM potentials, and area of damaged or lost OHCs, but not with the numbers of damaged or lost OHCs in the cochlea. It can be concluded that continuous industrial noise causes a damage to OHCs which differs form the damage caused by impulse noise.

Animals↗
PubMed2000

[Scanning electron microscopic findings concerning the formation of the organ of Corti near the helicotrema in guinea pigs].

We report on findings in guinea pigs with objectively tested normal hearing ability. At the apical end of the Corti organ only in the inner row of hair cells the stereociliae are detectable by scanning electron microscopy. Here the row is interrupted several times. Near the helicotrema we find first the inner row of the outer hair cells, then the middle row and finally the outer row. At the beginning of the D-turn their arrangement is disordered. Normally, at the basal end of the D-turn all rows of inner and outer hair cells show their typical formation. This finding should be taken into consideration when making a cochleogram for proving of experimental noise damages.

Animals↗
PubMed2000

Endourologic management of malignant ureteral strictures.

PURPOSE: This retrospective analysis assessed the efficacy of balloon dilatation, endoureterotomy, percutaneous ureteroneocystostomy with stenting, and insertion of Wallstents in the management of malignant ureteral strictures with an intact or compromised vascular supply. PATIENTS AND METHODS: A series of 127 patients with ureteral strictures secondary to malignancies were assessed after at least 2-year follow-up (range 2-5 years; mean 3.5 years). Balloon dilation (antegrade approach) was applied in 46 patients, endoureterotomy with temporary stenting in 37, percutaneous ureteroneocystostomy with stenting in 34, bougie and stents in 13, and Wallstents in 31. RESULTS: Balloon dilatation was successful in only two of four malignant midureteral stenoses with intact vascular supplies and was even less successful (10%) in midureteral strictures with a compromised vascular supply. Endoureterotomy failed in all cases to prevent ureteral obstruction. Percutaneous ureteroneocystostomy achieved patency in 11 of 34 patients (33%) having a compromised ureteral vascular supply. Wallstents were successful in 18 of 31 patients (58%) with stenoses of the pelvic ureter. CONCLUSIONS: Percutaneous ureteroneocystostomy with stenting meets the requirement for palliation in patients with obstruction secondary to pelvic neoplasms. Wallstents proved to be most successful when used in the pelvic ureter.

Adult↗
PubMed2000

The appendix as right ureteral substitute in children.

PURPOSE: The appendix has occasionally been used to replace sections of the right ureter. We reviewed the literature of the last 25 years on the use of the appendix as right ureteral replacement and report our experience with right ureteral substitution using the appendix. MATERIALS AND METHODS: We retrospectively reviewed the charts of 3 children who underwent appendiceal replacement of the right ureter. The appendix replaced the upper third of the ureter and the lower ureter in 1 and 2 cases, respectively. RESULTS: Followups of 4, 7 and 15 years, respectively, demonstrated that the appendix transports urine satisfactorily and permits renal function to be maintained with no evidence of obstruction. CONCLUSIONS: We believe that our small series supports the use of the appendix as a right ureteral substitute in select cases.

Adult↗
PubMed1999

Hypoxia- and hypercapnia-induced DC potential shifts in rat at the scalp and the skull are opposite in polarity to those at the cerebral cortex.

In anaesthetized and artificially ventilated rats DC (direct current) potential shifts induced by hypoxia or hypercapnia for 10 min were monitored at the surface of the skin, of the skull and of the cerebral cortex. Hypoxia was induced by decreasing the inspiratory O2 content from 20 to 10 or to 6% O2 in N2. Hypercapnia was induced by applying gas mixtures with CO2 contents from 0 to 5, 10, 20 or 30% CO2 in O2. DC potentials were recorded with non-polarizing electrodes filled with 150 mM NaCl solution. Hypercapnia evoked a negative DC shift (1.2-1.9 mV) epicranially and a large positive DC deflection (8.8-17.1 mV) epidurally. In contrast, hypoxia elicited a positive DC shift in skull recordings with a negative DC shift (2.6-3.1 mV) overshooting the baseline during recovery. DC shifts at the skin were positive, but smaller in amplitude (up to 3.1 mV). At the surface of the dura hypoxic DC shifts were negative and smaller (1.5-2.2 mV) than at the skull. The results show that a negative DC shift induced by hypercapnia recorded non-invasively from the skin or the skull is not always reflecting an increased cortical activation state and, vice versa, a positive DC shift does not always reflect a decreased state of neuronal activation. The electrogenesis of gas content-induced potentials could be due to the electrochemical diffusion of ions through the selective permeability barrier between the blood and tissue compartment. These observations are relevant for any application of non-invasive DC electroencephalography in the human cortex.

Animals↗
PubMed1999

Retinoid and androgen regulation of cell growth, epidermal growth factor and retinoic acid receptors in normal and carcinoma rat prostate cells.

Recent in vivo and in vitro studies suggest that retinoic acid receptor (RAR)-mediated processes may be involved in androgen regulation of prostate cells in a manner that may be altered during prostatic carcinogenesis. We tested this hypothesis in the newly established carcinoma and non-carcinoma rat prostate epithelial cell lines, NRP-154 and NRP-152, respectively. In DMEM/F-12 medium supplemented with 10% charcoal stripped fetal calf serum (cFCS), the number of both NRP-152 and NRP-154 cells were stimulated by testosterone (T), with a 4-fold greater effect in NRP-152 than in NRP-154 cells. Retinoic acid (RA) alone also stimulated the growth of NRP-152 cells, but failed to induce cell growth of NRP-154 cells. Importantly, the level of RAR alpha mRNA was elevated whereas the levels of RAR gamma and androgen receptor (AR) mRNA were lower in NRP-154 cells compared to those in NRP-152 cells. Treatment of NRP-152 cells with increasing doses of T resulted in a dose-dependent decrease and rebound of the level of RAR alpha and gamma mRNA in NRP-152 cells; these effects were not apparent, if not reversed, in NRP-154 cells. Both ligand binding and Western blot analyses revealed that epidermal growth factor receptor (EGF-R) was stimulated by 20 nM T but was suppressed by 0.1 microM RA, which also attenuated the stimulating effects of T on EGF-R in NRP-152 and to a lesser extent in NRP-154 cells. The differences in the level and androgen regulation of RAR mRNAs and reciprocal regulation of EGF-R expression by T and RA between NRP-154 and NRP-152 cells suggest that variations in the EGF-R and RAR signal events may contribute to differences in growth rate between these two cell lines.

Animals↗
PubMed1999

Percutaneous nephrostomy as adjunct management in advanced upper urinary tract infection.

OBJECTIVES: To determine by retrospective review of 315 percutaneous nephrostomies, performed for pyonephrosis, whether this intervention has major clinical advantages. METHODS: From 1977 to 1996, under the direct supervision of the senior author of this report (E.K.L.), at seven hospital sites, 315 patients (181 males, 134 females; 17 to 88 years of age) were treated with percutaneous nephrostomy and antibiotic therapy for infected hydronephrosis. RESULTS: Additional or disparate pathogens were identified in 116 (36.8%) of 315 patients, leading to a clinically significant change in, or addition of, antibiotics and/or antifungal agents in 84 (73%) of 116. Most notably, we often found a clinically important disparity between the results of cultures obtained from the nephrostomy and those obtained from bladder-urine specimens. CONCLUSIONS: This retrospective review confirms previously reported advantages of percutaneous upper urinary tract drainage as a potentially life-saving adjunct in the treatment of pyonephrosis. Several case studies highlight the advantage of this maneuver in difficult cases involving obstruction due to extensive fungus or debris. In particular, our review focuses attention on the clinically important insight that urine cultures from percutaneous nephrostomy drainage often identify pathogens that differ from those detected in concurrent bladder cultures.

Humans↗
PubMed1999

Management of victims of urban chemical attack: the French approach.

Since the early 1980s several disasters involving mass release of toxic substances have focused the attention of different administrations and the fire services into producing protocols and guidelines for action in civilian situations. The bomb attack in the Tokyo subway, in March 1995, made it clear that a terrorist attack using highly toxic agents is now feasible. Management of disasters in the civil sector in France is based upon two interlinked plans: the Red Plan, which covers on-site organisation, and the White Plan, which concerns the interface with hospital services. Special procedures have been developed to adapt the Red and White Plans for use in the event of toxic attack and concern the deployment of emergency responding personnel, the provision of life support and antidotes in the contaminated zone, the prevention of secondary contamination and the transport and reception of victims at the hospital. Based on the established principle of pre-hospital resuscitation and well-tried assistance plans, this doctrine allows a safe and effective response to terrorist attacks as well as to other toxic release incidents.

Decontamination↗
PubMed1999

Salvage continent vesicostomy after enterocystoplasty in the absence of the appendix.

PURPOSE: We describe a surgical procedure for a select group of children who had previously undergone augmentation enterocystoplasty, following which intermittent catheterization became more and more difficult or impractical. A new access to the reservoir became necessary, and alternative conduits included the appendix, ureter and tubularized ileum or stomach. Each conduit had its advantages and disadvantages but all required transperitoneal dissection. We report a simple extraperitoneal surgical technique that involves use of the Mitrofanoff and Nissen principles. MATERIALS AND METHODS: A 2x6 cm. flap of the anterior wall, which is usually intestine, of the augmented bladder is raised. The base of the flap is just below the bladder dome. The flap is then tubularized over a 14F catheter and the cystostomy is closed. The bladder is plicated around the base of the tube, similar to the Nissen gastroesophageal fundoplication. The plication extends and covers the proximal 3 cm. of the tube. Intraoperative bladder distention is performed to confirm the competence of the continence mechanism. The distal part of the tube is then anastomosed to the inverted umbilical skin or to a tubularized abdominal wall skin flap. RESULTS: The aforementioned technique was used in 5 children 3 months to 6 years old. Earlier augmentation ileocystoplasty and bladder neck reconstruction had been performed in 4 children. The appendix was unavailable for a Mitrofanoff vesicostomy in all cases. This procedure was also performed on a 13-year-old boy with severe myogenic detrusor failure, due to posterior urethral valves, and a bladder capacity of 700 ml. There was no significant surgical morbidity and all children are dry between clean intermittent catheterizations 1 to 5 years postoperatively (mean 3.3). CONCLUSIONS: Use of the Mitrofanoff and Nissen principles proved to be simple and reliable, and avoided secondary intraperitoneal exploration and use of bowel in these select cases.

Child↗
PubMed1998

Postnatal conditioning for spreading cortical depression in the rat brain.

The cerebral cortex of anaesthetised 2- to 12-day-old rats was superfused with artificial cerebrospinal fluid containing 100 mM acetate substituted for chloride to condition the brain for spreading depression (SD). After such superfusion, the earliest SD-like events were found at day 9 and full blown SD at day 10, whereas in the unconditioned brain the first SD occurred between days 12 and 15. Acetate conditioning of the cerebral cortex may be used to unmask neuronal and glial properties that are hidden in early stages of development.

Acetates↗
PubMed1998

Comparison of the phagocytosis of two types of cyclosporin (SDZ OXL 400 and SDZ IMM 125) by alveolar macrophages from hamsters.

The aim of this study was to compare two types of cyclosporin (Cs) particles, SDZ OXL 400 and SDZ IMM 125, the latter being more hydrophilic, to understand their uptake by airway macrophages. Alveolar macrophages (AM), harvested by bronchoalveolar lavage (BAL) of hamster lungs, were cultured with two different doses (0.1 mg and 0.5 mg) for 1 h, 6 h, and 24 h. Control incubations without Cs particles or with latex particles were carried out simultaneously. Cell viability, cell activation (i.e., respiratory burst, interleukin-6 (IL-6) synthesis) and mean volume of particles phagocytosed per macrophage were measured. Both types of Cs particles did not modify the AM viability, and failed to induce IL-6 synthesis during phagocytosis but slightly decreased the cell oxidative respiratory burst. The comparison between SDZ OXL 400 and SDZ IMM 125 showed that for the lower dose the mean volume of both Cs types phagocytosed was similar at 1 h and 6 h. At 24 h an increase of the mean volume phagocytosed was seen for SDZ IMM 125 but not for SDZ OXL 400. For the higher dose the mean volume of SDZ IMM 125 phagocytosed was higher than SDZ OXL 400 at 1 h and 6 h and comparable for both types at 24 h. SDZ IMM 125 particles were phagocytosed more rapidly than SDZ OXL 400. The mean volume of phagocytosed latex particles increased with time and dose and was higher than for both Cs particle types. In conclusion, AM were seen to phagocytose particles of different physical properties (i.e., form, size, and shape), chemical properties (i.e., inert or peptidic) and degrees of hydrophilicity in a different manner.

Animals↗