Mechanism of repression of RNA polymerase I transcription by the retinoblastoma protein

The retinoblastoma susceptibility gene product pRb restricts cellular proliferation by affecting gene expression by all three classes of nuclear RNA polymerases. To elucidate the molecular mechanisms underlying pRb-mediated repression of ribosomal DNA (rDNA) transcription by RNA polymerase I, we have analyzed the effect of pRb in a reconstituted transcription system. We demonstrate that pRb, but not the related protein p107, acts as a transcriptional repressor by interfering with the assembly of transcription initiation complexes. The HMG box-containing transcription factor UBF is the main target for pRb-induced transcriptional repression. UBF and pRb form in vitro complexes involving the C-terminal part of pRb and HMG boxes 1 and 2 of UBF. We show that the interactions between UBF and TIF-IB and between UBF and RNA polymerase I, respectively, are not perturbed by pRb. However, the DNA binding activity of UBF to both synthetic cruciform DNA and the rDNA promoter is severely impaired in the presence of pRb. These studies reveal another mechanism by which pRb suppresses cell proliferation, namely, by direct inhibition of cellular rRNA synthesis.

Analysis of aircraft exhausts with Fourier-transform infrared emission spectroscopy

Because of the worldwide growth in air traffic and its increasing effects on the atmospheric environment, it is necessary to quantify the direct aircraft emissions at all altitudes. In this study Fourier-transform infrared emission spectroscopy as a remote-sensing multi-component-analyzing technique for aircraft exhausts was investigated at ground level with a double pendulum interferometer and a line-by-line computer algorithm that was applied to a multilayer radiative transfer problem. Initial measurements were made to specify the spectral windows for traceable compounds, to test the sensitivity of the system, and to develop calibration and continuum handling procedures. To obtain information about the radial temperature and concentration profiles, we developed an algorithm for the analysis of an axial-symmetric multilayered plume by use of the CO(2) hot band at approximately 2400 cm(-1). Measurements were made with several in-service engines. Effects that were due to engine aging were detected but have to be analyzed systematically in the near future. Validation measurements were carried out with a conventional propane gas burner to compare the results with those obtained with standard measurement equipment. These measurements showed good agreement to within +/-20% for the CO and NO(x) results. The overall accuracy of the system was found to be +/-30%. The detection limits of the system for a typical engine plume (380 degrees C, ? = 50 cm) are below 0.1% for CO(2), ~0.7% for H(2)O, ~20 ppmv (parts per million by volume) for CO, and ~90 ppmv for NO.

Infrared spectroscopy of tropospheric trace gases: combined analysis of horizontal and vertical column abundances

Vibration-rotation absorptions in high-resolution Fourier-transform infrared spectra from a 246-m horizontal path were used to derive local concentrations of trace gases at the Alpine observatory at the Zugspitze summit, Germany (2964 m above sea level). The analysis was performed by using the line-by-line nonlinear least-squares spectral fitting software, SFIT, based on the 1992 HITRAN line parameter compilation. (HITRAN is a high-resolution transmission molecular absorption database.) A comparison to in situ measurements shows an agreement of better than 4.3% for the species CO, CO(2), and CH(4). Using the same spectrometer and analysis software, we obtained the vertical column density of N(2)O together with an adjusted vertical volume mixing ratio distribution. This translates to a local N(2)O concentration at the altitude of Zugspitze that agrees with the horizontal path-derived value to within 1%.

[Is primary would closure in septic pediatric surgery contraindicated?]

Since 1994, 25 children have been treated for abscesses of the soft issue. After the incision, a complete debridement was done, followed by implantation of a collagen sponge containing gentamicin and primary wound closure. Only two relapse were seen, which had to be re-opened.

Continuous extracorporeal stool-transport system: a new and economical procedure for transitory short-bowel syndrome in prematures and newborns

Between May 1994 and June 1995, nine newborns underwent surgery due to mechanical ileus or intrauterine perforation of the small bowel. Three were very-low-birth-weight infants weighing between 520 and 1,200 g. Surgery was performed in the first 2 days of life and split ileo- or jejunostomas were implanted. Early oral nutrition was initiated. To avoid non-use of the distal bowel and short-bowel syndrome, the aboral stoma was irrigated a few days later with the proximal feces. A new technique was applied to transport the chyle continuously from the oral to the aboral stoma: the stool was collected in an especially constructed stoma bag and transported distally by a roller pump. No major complications were seen. The general outcome was excellent in all cases, and reanastomosis under optimal bowel conditions was achieved in all patients without further problems.

[Surgical procedure in children with medullary thyroid gland carcinoma with reference to multiple endocrine neoplasia type II]

Between 1988 and 1995 we treated ten patients aged 7-18 years for familial MTC or MEN II syndrome with a total of 17 operations. Using these surgical procedures, 6/9 patients remained free of tumor after 0-8 years (mean 4.5 years). In conclusion, we recommend thyroidectomy [1] in children younger than 5 years of age and a family history of MEN IIa; [2] in children younger than 3 years of age, presenting the characteristic phenotype of MEN IIb, both with a positive test for mutation of the RET protooncogene [4].

Monoclonal anti-FLAG antibodies react with a new isoform of rat Mg2+ dependent protein phosphatase beta

The FLAG peptide has been widely used as a multi-purpose tag for the identification and detection of recombinant FLAG fusion proteins. The practicability of this approach depends on specific detection of FLAG fusion proteins with no or very little cross-reactivity to cellular proteins. We have isolated a rat cDNA clone coding for a new splicing isoform of Mg2+ dependent protein phosphatase beta (MPP beta) by screening a rat brain expression library with monoclonal antibody Anti-FLAG M2. MPP beta reacts strongly both as a MPP beta-beta-galactosidase- and as a glutathione S-transferase fusion protein with anti-FLAG M2 antibodies. Sequence analysis of MPP beta revealed a sequence motif with five out of eight amino acid residues identical to the FLAG peptide hitherto believed to be mono-specific.

[Cystic degeneration of the adventitia of the popliteal artery as a possible sequela of entrapment syndrome]

We report two cases of cystic adventitial degeneration of the popliteal artery in young sportsmen. The pathogenetic role of microtrauma is suggested by the localisation of the adventitial cysts, the clinical symptoms, as well as the immunohistochemical demonstration of foamy macrophages instead of endothelial cells in the wall of the cysts. In one case the cause of the intermittent claudication could be verified by duplex sonography and comparison of the arterial pressure of both legs with a Doppler method only after physical exercise. As expected, an angiodilatation has only a temporary effect. Therefore a surgical resection of the cyst or of the involved arterial segment had be performed.

Periodic firing pattern in afferent discharges from electroreceptor organs of catfish

Spontaneous afferent activity was recorded from 26 single ampullary electroreceptive organs of freshwater catfish (Ictalurus nebulosus LeS) at various temperatures. Regular grouping of action potentials was apparent in this secondary sensory system at 35 degrees C and occasionally at 30 degrees C. Impulse groups consisted of up to seven impulses. The precise timing of impulse generation and the temporal sequence of impulses indicated that oscillating processes are involved. Expectation density functions were calculated for records of afferent activity obtained at various temperatures below 35 degrees C. In the majority of records the function was periodic. Impulse grouping and expectation density functions became more distinct in units exhibiting extremely high thresholds (i.e. being insensitive) to electrical stimuli. The results suggest that the oscillations originate from the postsynaptic membrane. The temporal pattern of impulse generation within impulse groups of ampullary electroreceptor organs and of specific warm and cold receptors was compared and found to be similar. Application of cadmium and menthol, which both reduce calcium entry, suppressed spontaneous activity in normal and insensitive electroreceptor systems, attenuated the sensitivity of normal receptors and modified the periodic pattern. This indicates that calcium is implicated in sensory transduction and in postsynaptic mechanisms. The data suggest that an oscillating process is one component of signal transmission in ampullary electroreceptor organs of teleost fish.

[Effect of diclofenac and flurbiprofen on the course of inflammation after cataract extraction]

In a prospective, randomized, double-blind study the effect of different anti-inflammatories (diclofenac 0.1%, flurbiprofen 0.03%) versus placebo on the intra- and postoperative inflammation in 65 eyes was examined. Prednisolone acetate 0.5% eye drops were the basic therapy in all three groups. As criteria served the difference between pre- and postoperative flare and cell concentration in the anterior chamber, measured using the laser flare cell meter, the clinical course, and the level of the inflammatory mediator 6-oxo-PGF1 alpha (prostacyclin) in the aqueous humor after intraoperative paracentesis, determined by means of enzyme-linked immunosorbent assay. The level of prostacyclin was not influenced in any of the three groups. The numbers of cells decreased continuously, but without marked differences among the groups. On the basis of the concentration of protein measured in the aqueous humor and the clinical course, diclofenac 0.1% proved to be a more potent additive anti-inflammatory therapy than flurbiprofen 0.03% immediately after the surgical procedure (P = 0.039 at 1 day after operation), but the final results (4 weeks after operation) revealed no detectable difference. By application of placebo, an obvious higher concentration of protein was measured during all the observations (P = 0.0002). Therefore in the case of cataract extraction the local steroidal therapy should be combined with nonsteroidal anti-inflammatory drugs (cyclooxygenase inhibitors).

Characterization of the Han:SPRD rat model for hereditary polycystic kidney disease

The Han:SPRD rat model for inherited polycystic kidney disease (PKD) was characterized (clinical parameters, morphology, immunohistochemistry and in situ hybridization). Homozygous animals died of uremia after three to four weeks with severe cystic transformation of virtually all nephrons and collecting ducts (serum urea: 616 +/- 195 mg/dl; kidney-to-body weight ratio: > 20%). In heterozygotes, slow progression of the disease led to death between the 12th and 21st month (median: 17 months; serum urea levels above 200 mg/dl). Kidney enlargement was moderate, and cysts were restricted to the cortex and outer medulla. Immunohistochemical markers showed that approximately 75% of the cysts were derived from the proximal tubule. Cystic transformation started in the proximal tubule with a sharp onset of basement membrane alteration and a loss of epithelial differentiation restricted to small focal areas. In these areas, alpha 1(IV) collagen and laminin B1 mRNA were enhanced as revealed by isotopic and non-isotopic in situ hybridization. Fibroblasts underlying the affected tubular portions were involved in matrix overexpression resulting in subepithelial accumulation of immunoreactive collagen IV and laminin. In later stages of cystic transformation distal nephron segments were affected as well. A reversal in epithelial polarity as judged from Na,K-ATPase-immunoreactivity was not observed. Renal immunoreactive renin-status was significantly decreased. Hematocrit was lowered in heterozygotes (40.4 +/- 5.8 vol% compared to 46.7 +/- 1.99 vol% in controls; P < 0.05) and total renal EPO mRNA was reduced to 36 +/- 14% of the mean value of control animals, whereas serum EPO levels were not significantly altered. We conclude that the Han:SPRD rat is a useful model for the study of human ADPKD since both diseases are similar in several aspects. The model is particularly suitable for the study of epithelial-mesenchymal interactions at the beginning of tubular cystic transformation.

Inspection of non-CO2 greenhouse gases from emission sources and in ambient air by Fourier-transform-infrared-spectrometry: Measurements with FTIS-MAPS

Infrared spectrometry is a versatile basis to analyse greenhouse gases in the atmosphere. A multicomponent air pollution software (MAPS) was developed for retrieval of gas concentrations from radiation emission as well as absorption measurements. Concentrations of CO, CH4, N2O, and H2O as well as CO2, NO, NO2, NH3, SO2, HCl, HCHO, and the temperature of warm gases are determined on-line. The analyses of greenhouse gases in gaseous emission sources and in ambient air are performed by a mobile remote sensing system using the double-pendulum interferometer K300 of the Munich company Kayser-Threde. Passive radiation measurements are performed to retrieve CO, N2O, and H2O as well as CO2, NO, SO2, and HCl concentrations in smoke stack effluents of thermal power plants and municipal incinerators and CO and H2O as well as CO2 and NO in exhausts of aircraft engines. Open-path radiation measurements are used to determine greenhouse gas concentrations at different ambient air conditions and greenhouse gas emission rates of diffusive sources as garbage deposits, open coal mining, stock farming together with additional compounds (e.g. NH3), and from road traffic together with HCHO. Some results of measurements are shown. A future task is the verification of emission cadastres by these inspection measurements.

Focal overexpression of collagen IV characterizes the initiation of epithelial changes in polycystic kidney disease

Changes of extracellular matrix are involved in the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD). The relationship between epithelial changes and extracellular matrix production was studied in a new rat model (Han:SPRD/cy+) at an early phase of cystogenesis. Messenger RNA expression of the alpha 1(IV)-chain of collagen type IV, the main structural component of basement membrane, was localized by in situ hybridization. The presence of collagen IV-protein was shown by immunohistochemistry. At an initial stage, cysts were lined with normal-appearing epithelium except for focal zones of less differentiated cells exhibiting strong collagen alpha 1(IV) mRNA expression and a thickened basement membrane. In these zones, an increase in cell number (2.39-fold) per unit epithelial area indicated hyperplastic growth. Conspicuously, these zones were found at 'bottleneck'-like transitions from normal-size tubules to cystic expansions. Intermediate stages of cysts showed more prominent extracellular matrix deposits and an overall maximally enhanced collagen IV mRNA expression, whereas terminal stages were lined with a flat, simplified epithelium and exhibited moderate collagen IV expression. We suggest that focally enhanced expression of collagen IV in the tubular epithelium and surrounding interstitium of Han:SPRD/cy+ rat kidney is initially involved in cyst development.

[Subcutaneous struma recurrence as a sequela of autologous thyreocyte implantation]

Goiter recurrence is a well known fact in the surgical therapy of thyroid diseases. Extremely rare the goiter recurrence is localized in the subcutis or the muscle of the neck. We report on two patients with this type of recurrence. The reason may be an autologous implantation of thyroid follicle cells intraoperatively. It can be avoided by removing all particles of the thyroid gland from the operation area.

Oscillation and noise determine signal transduction in shark multimodal sensory cells

Oscillating membrane potentials that generate rhythmic impulse patterns are considered to be of particular significance for neuronal information processing. In contrast, noise is usually seen as a disturbance which limits the accuracy of information transfer. We show here, however, that noise in combination with intrinsic oscillations can provide neurons with particular encoding properties, a discovery we made when recording from single electro-sensory afferents of a fish. The temporal sequence of the impulse trains indicates oscillations that operate near the spike-triggering threshold. The oscillation frequency determines the basic rhythm of impulse generation, but whether or not an impulse is actually triggered essentially depends on superimposed noise. The probability of impulse generation can be altered considerably by minor modifications of oscillation baseline and amplitude, which may underlie the exquisite sensitivity of these receptors to thermal and electrical stimuli. Additionally, thermal, but not electrical, stimuli alter the oscillation frequency, allowing dual sensory messages to be conveyed in a single spike train. These findings demonstrate novel properties of sensory transduction which may be relevant for neuronal signalling in general.

Breath hydrogen excretion in patients with alcoholic liver disease--evidence of small intestinal bacterial overgrowth

The hydrogen breath test has been used to investigate the incidence of small-bowel bacterial overgrowth in 45 chronic alcoholics and in 60 controls with no history of alcohol abuse. In the group of patients with alcoholic liver disease, the percentage of cases with bacterial overgrowth was almost three times (37.8%) that of controls not abusing alcohol (13.3%; p < 0.001). A separate evaluation of alcoholics with cirrhosis in comparison with those without cirrhosis, revealed no significant difference in the incidence of bacterial overgrowth (42.9% and 33.3%; p > 0.05). Some 16.7% of the controls and 8.9% of the patients with alcoholic liver disease were classified as "non-excreters". Among patients with alcoholic liver disease, the mouth-to-caecum transit time was prolonged by 21.5% in comparison with the controls not abusing alcohol (p < 0.025). The results suggest that bacterial overgrowth might contribute to the functional and/or morphological abnormalities of the small intestine commonly found in patients with chronic alcohol abuse.

Rare ovarian tumors in childhood

Between 1972 and 1990 44 patients with ovarian tumors were treated at the Department of Pediatric Surgery of the University of Heidelberg. 27 patients (61%) suffered from tumor-like lesions: neonatal, pubertal (functional) cysts, and cysts in case of syndromes. 17 genuine tumors were found (39%): 8 germ-cell tumors, 7 cystomas respectively cystadenomas and 2 tumors of the gonadal stroma. Malignancy has been observed only in two cases: 1 malignant teratoma and 1 malignant granulosa-theca-cell tumor. 2 tumor-like lesions were caused by syndromes: Albright-McCune-Sternberg- and Stein-Leventhal syndrome: Treatment of uncommon tumors depends on their size, hormonal activity, on the syndromes with which they are associated, and on the tumor status.

[Revascularization of colonic anastomoses]

The revascularization of colonic anastomosis after colon segmental resection in rabbits in 9 different end-on-end and inverting suture techniques was examined macroscopically, microangiographically, micropreparatorily and histologically. Independently of the suture technique revascularization started 4 days after surgery. 8 days postoperatively the suture line is mainly bridged, 14 days postoperatively the vasal connection to the opposite side is completed. The new vessels mainly originate from the subserosal and submucosal tissue. The adhesions participate in the revascularization, too. It (the revascularization) directly correlates with the development of granulation tissue. This is evident from the excess reactive revascularization of abscesses and ulcers in the anastomoses. There always results a vascular scar in the angioarchitecture of the colonic wall. Start and extent of the revascularization cannot--in contrast to former literature--be looked at as a guarantee of quality for the healing of anastomoses.

[Extremity-threatening ischemia in ergotism. Successful treatment with the intra-arterial administration of nifedipine]

A 39-year-old woman suffering from migraine took two suppositories of an ergotamine-containing proprietary drug (Cafergot, containing 2 mg ergotamine tartrate) for the first time again after an abstinence of two years. Twenty-four hours later she developed symptoms of decreased peripheral blood flow in all four limbs. Walking distance without pain was reduced to 100 m, but the severest changes affected the right arm, with livid discolorations and complete immobility 16 hours after the onset of symptoms. Despite administration of morphine derivatives the pain progressively increased. Angiography demonstrated spastic narrowing of all arm arteries below the axillary artery. No vessels were visualized below the lower-arm bifurcation. Thereupon 4 mg nifedipine were injected through the angio-catheter within 30 min (five individual doses of 0.8 mg each). This was followed by intravenous infusion of 0.5 mg/h. The pain immediately decreased and the livid discoloration as well as impaired arm movement improved. A residual deficit, incomplete lesion of the median nerve, persisted but gradually regressed during the following two months.

Discharge pattern analysis suggests existence of a low-threshold calcium channel in cold receptors

The regular periodic activity patterns of mammalian cold receptors have been quantitatively studied. Analysis of the timing of either single impulses or impulse groups demonstrated that the periodic receptor process is maintained independently of impulse generation and continues to operate under conditions when afferent impulses are not initiated. These results imply that the underlying conductances must be operational at threshold potentials related to impulse generation. In addition to temperature, the periodic process is considerably sensitive to calcium, which affects mainly the probability of impulse generation during each cycle. Reduction of external calcium and application of calcium entry blockers with relative selectivity for low-threshold calcium channels are similarly effective in modulating cold receptor activity. The data imply the existence of a low-threshold calcium conductance at the sensory terminal.

Ampullary electroreceptors in catfish (Teleostei): temperature dependence of stimulus transduction

The response properties of ampullary electroreceptors have been studied in the catfish Ictalurus nebulosus at skin temperatures between 5 and 35 degrees C. A unimodal relationship between spontaneous activity and temperature was obtained. Mean (+/- SEM) peak discharge rate was 57.3 +/- 1.8 impulses s-1 at 25 degrees C; the receptors were active at 5 degrees C (15.0 impulses s-1) and at 35 degrees C (31.5 impulses s-1). There were no dynamic responses to temperature changes in either the warming or cooling direction. The shape of the frequency characteristic depended on temperature: the peak of the gain curve shifted to low frequencies at low temperatures. There was a concomitant change of the phase characteristic: the intersection at zero degree phase angle shifted to higher frequencies with an increase of temperature, thus increasing the lead at lower frequencies and decreasing the lag at higher frequencies. Latency after combined excitatory and inhibitory impulse stimulation was temperature dependent, ranging from 16.4 ms (5 degrees C) to 5.6 ms (35 degrees C). Application of the specific calcium channel blocker menthol (0.2 mM) suppressed spontaneous activity, the effect becoming more prominent at higher temperatures. Sensitivity to sinusoidal electrical stimulation was also impaired, but to a lesser degree and mainly at lower temperatures. We conclude that the filter properties of the receptor organ can be modelled by a band-pass filter in series with a latency, both of which are temperature dependent. These filter properties might be partially based on the activation kinetics of the transduction channels.

Modulation of periodic cold receptor activity by ouabain

The effect of ouabain on the periodic discharge pattern of feline cold receptors was studied in order to substantiate a possible contribution of Na/K pump activity to signal transduction. Afferent activity was recorded from the cold fibres of an isolated preparation of the tongue. The periodic pattern consisted of beating activity and of grouped discharges and was characterized by two parameters, the oscillation frequency and the number of impulses initiated per cycle. Ouabain (10(-7)-10(-6)M) induced in all receptors excitatory responses, consisting of a short vigorous increase of activity followed by inhibition. Thus the receptors never stabilized to or maintained a new static level of activity. The ouabain-induced responses occurred repeatedly in several receptors and were produced by remarkable stereotyped modifications of both the oscillation frequency and the number of impulses per cycle. The oscillation frequency attained peak values which increased monotonically with higher static temperatures and which were considerably greater than peak control values. The data indicate that an electrogenic Na/K pump contributes to the transducer process of cold receptors and that inhibition of this pump evidently gives rise to a depolarizing imbalance of the membrane potential, accelerating the oscillation frequency to a maximum value. Thus the oscillation frequency seems to be controlled by temperature and by membrane potential in cold receptors.

[Surgical therapy of malrotations in childhood]

From a total of 174 children treated with malrotations from 1971 to 1988, 148 could be evaluated for long-term results of surgical treatment. The various modalities of treatment were: no correction, dissection of Ladd's bands only, caecoascendopexy, Ladd's procedure and the so-called total correction. Comparing the late results in children with and without correction it was found that those without correction, i.e. without pexy, had to be reoperated in 17% of the cases, whereas the totally corrected children required reoperation in 8% of the cases only. Corrected cases needed to be admitted but not operated later because of pain, constipation, vomiting or poor weight gain in 23%, the uncorrected ones in 6%. Likewise, corrected malrotations resulted in complaints in 27% in contrast to the noncorrected ones in 9%. The conclusion is that total correction results in fewer reoperations but in more symptoms not requiring surgery.

Analysis of facial cold receptor activity in the rat

Afferent activity of single facial cold receptors was extracellularly recorded from infraorbital nerve fibers in the rat, and the response properties of 28 receptors to thermal stimulation were quantitatively studied. Generally, on repeated stimulation, the afferent activity was highly reproducible and was not dependent on previous adapting temperatures. At constant temperatures, a periodic pattern was apparent in the discharges of 24 receptors; in the remaining 4 receptors periodic elements could not reliably be detected. The temperature dependence of the cyclic pattern corresponded to that observed in other mammalian cold receptor populations: we observed regular impulse groups (bursts) at lower and beating activity at higher adapting temperatures. Rapid changes of temperature induced transient alterations of activity. The dynamic response to cooling was biphasic, indicating a complex sequence of receptor events. A transient acceleration of impulse frequency was followed by a dynamic burst discharge which was characterized by longer pauses and a greater number of impulses per burst compared with the steady-state activity at the same temperature. This indicates a deceleration of the periodic receptor events during the adaptation process following dynamic responses, which is accompanied by a concomitant shift of these processes to a more pronounced suprathreshold condition. In an additional series of experiments, parameters of the periodic activity in the rat were compared with corresponding data of facial and lingual cold receptors in the cat. Whereas the number of impulses per cycle was similar in the 3 receptor populations, the frequency of the periodic pattern proved to be considerably higher in the rat than in the cat.