NOViSE: a virtual natural orifice transluminal endoscopic surgery simulator

Purpose: Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a novel technique in minimally invasive surgery whereby a flexible endoscope is inserted via a natural orifice to gain access to the abdominal cavity, leaving no external scars. This innovative use of flexible endoscopy creates many new challenges and is associated with a steep learning curve for clinicians. Methods: We developed NOViSE - the first force-feedback enabled virtual reality simulator for NOTES training supporting a flexible endoscope. The haptic device is custom built and the behaviour of the virtual flexible endoscope is based on an established theoretical framework – the Cosserat Theory of Elastic Rods. Results: We present the application of NOViSE to the simulation of a hybrid trans-gastric cholecystectomy procedure. Preliminary results of face, content and construct validation have previously shown that NOViSE delivers the required level of realism for training of endoscopic manipulation skills specific to NOTES Conclusions: VR simulation of NOTES procedures can contribute to surgical training and improve the educational experience without putting patients at risk, raising ethical issues or requiring expensive animal or cadaver facilities. In the context of an experimental technique, NOViSE could potentially facilitate NOTES development and contribute to its wider use by keeping practitioners up to date with this novel surgical technique. NOViSE is a first prototype and the initial results indicate that it provides promising foundations for further development

Nitrate poisoning in cattle. 5. The effect of tungsten on nitrate formation by rumen microbes.

Sodium tungstate added to rumen fluid depressed the nitrate reductase activity of rumen microbes. The rate of nitrite formation in rumen fluid fell by about 86% if 20 mu mol of Na2WO4 were added per litre. At 100 and 500 mu mol/l no nitrite accumulation was observed. This inhibition was overcome by molybdenum. Experiments in cows confirmed these in vitro findings. Tungsten is suggested as a promising preventative of nitrite intoxication in ruminants. [For Part 3 see VB 50, abst. 5179.] (Abstract retrieved from CAB Abstracts by CABI’s permission

Nitrate poisoning in cattle. 6. Tungsten (wolfram) as a prophylactic against nitrate-nitrite intoxication in ruminants.

The amount of nitrite formed in the rumen after supply of potassium nitrate was decreased considerably by tungsten, which was administered as sodium tungstate to cows orally and by rumen fistula in daily doses of up to 6.6 mg per kg body weight. This effect of tungsten depends on the molybdenum content of the fodder and can be overcome in the case of high molybdenum levels. The relationship between the nitrate intake of the animal, the dose of tungsten administered to the animal daily and the highest concentration of nitrite reached in the rumen is given as a mathematical equation as well as in the form of a triangular diagram. By means of this three-element relationship and as a result of kinetic studies on the action of tungsten, a dosage pattern of tungsten was elaborated. The effectiveness of tungsten as a protective against nitrate intoxication was proved on cows dosed repeatedly as well as with single doses of nitrate up to 500 mg NO3 per kg body weight. It is concluded finally that tungsten offers a high degree of protection against nitrate toxicity to ruminants. (Abstract retrieved from CAB Abstracts by CABI’s permission

5 Równoczasowa chemioterapia chorych na drobnokomórkowego raka płuc (DKRP) w postaci ograniczonej. Doświadczenia własne w pilotowej grupie 32 chorych

W styczniu 1994 roku w Krakowskim Centrum Onkologii rozpoczęto prospektywne badanie II fazy celem oceny skuteczności i toksyczności równoczesnego leczenia chemicznego wg schematu EP (etopozyt + cysplatyna) i napromienianiem chorych na DKRP w postaci ograniczonej. Do lutego 1998 roku zakończono leczenie 32 chorych. W całej grupie uzyskano 21% 3-letnich aktualizowanych przeżyć bezobjawowych. Przeprowadzono analizę wpływu na wyniki leczenia takich czynników jak: profilaktyczne napromienianie mózgu, opóźnienie radioterapii w stosunku do leczenia chemicznego, liczba serii chemioterapii, zaawansowanie kliniczne według TNM, obecność regresji potwierdzonej w badaniu histologicznym. Uzyskane wyniki wstępne wskazują na konieczność dalszych modyfikacji protokołu leczenia

Nitrate poisoning in cattle. 7. Prevention.

Results are summarized from 44 feeding trials with dry or lactating cows fed hay, pre-wilted grass silage or freshly mown grass with or without concentrates. As nitrate content of the forage increased, the moment at which the highest methaemoglobin (MHb) concentration occurred was delayed. As the MHb peak increased, more time was required to reduce MHb to normal values of 2-3%. Dry matter (DM) intake varied with type of forage. Consumption of 1.1 kg DM/100 kg bodyweight required 2 hours with hay or silage and 3.5 h with fresh grass. The relationship between nitrate intake and the formation of MHb in the blood was used to calculate the amount of forage that may be consumed per meal without causing symptoms of nitrate poisoning. Hay and pre-wilted silage with a nitrate content of up to 0.75% in the DM may be given ad lib. Indoor feeding of freshly mown grass with a nitrate content of up to 1.5% may also be given with restriction. Under grazing conditions, grass with a nitrate content of 2% in DM was safe without restriction. Nitrate poisoning may also be prevented by inhibiting nitrate reduction in the rumen by a daily dose of tungsten (wolfram). However, all potential hazards of this prophylactic treatment need to be examined before its use under practical conditions can be recommended. (Abstract retrieved from CAB Abstracts by CABI’s permission

Intermittent or Continuous Therapy of Experimental Meningitis Due to Streptococcus pneumoniae in Rabbits: Preliminary Observations on the Postantibiotic Effect in Vivo

The relative effectiveness of bolus vs. constant intravenous administration of equivalent doses of penicillin G in killing bacteria in vivo was studied in a rabbit model of meningitis due to Streptococcus pneumoniae. Samples of cerebrospinal fluid (CSF) and serum were obtained from 30 rabbits at intervals of ⩽8 hr after treatment for determination of antibiotic concentrations and titers of viable bacteria in the CSF. When penicillin G was given by continuous infusion (105 units/hr after an initial l05-unit loading dose), concentrations of drug in serum and CSF reached a steady state in 1 hr. With intermittent bolus administration of 4 × 105 units every 4 hr, higher peak and lower trough concentrations were achieved, and these concentrations paralleled those in the CSF. Although an initial acceleration in bactericidal rate was observed with the bolus infusion between the first and second hour of therapy, after the second hour the rate of bacterial killing was identical for the two methods of administration. The duration of therapy required for sterilization of the CSF was dependent only on the bacterial count before treatment and not on the mode of drug administration. The effect of single bolus intravenous administration of ampicillin was examined in experimental pneumococcal meningitis. Ampicillin was given at various dosages (3.25-62.5 mg/kg), and frequent samples of CSF were obtained for determination of concentrations of pneumococci and ampicillin. A long postantibiotic effect was observed in the CSF of all animals, and this effect consistently was longer than that observed in vitr

Application of the Feynman-Kac path integral method in finding the ground state of quantum systems

Numerical methods of applying the Feynman-Kac path integral approach to quantum mechanics are presented. The methods are demonstrated on simple quantum mechanical systems, including the hydrogen atom, the simple harmonic oscillator and infinite square wells. New analytic results for the Wiener integrals are obtained and compared with numerical results. A measure of the statistical uncertainty is introduced and rates of convergence are investigated. Implementation of the method on both serial and parallel computers is discussed. © 1997 Elsevier Science B.V

Concurrent chemoradiotherapy in limited-stage small-cell lung cancer. Results of a pilot study

Between January 1994 and February 1998, 32, limited-stage small-cell lung cancer patients were treated with concurrent chemoradiotherapy. Follow-up time ranged from 4 to 34 months, (median 14 months). Complete regression was obtained in 22 of the 30 patients, who received at least four courses of EP chemotherapy and a tumour dose of 50 Gy or more. In all, 2-year actuarial disease-free survival was 21 %. Brain metastases occurred in 8 (36.4 %) patients with CR, in 5/7 (71.4 %) patients without prophylactic cranial irradiation (PCI) and in 3/15 (20 %) patients after PCI. The survival rate was lower in patients with PCI, in Whom chest irradiation was started later than one month from the beginning of course 1 of EP chemotherapy. We have suggested a modification of the treatment protocol

6 Wyniki leczenia u chorych na chłoniaki nieziarnicze o pośrednim i wysokim stopniu złośliwości po chemioterapii MACOP-B lub VACOP-B i radioterapii. Analiza czynników prognostycznych i próba oceny roli radioterapii

W okresie od 1986 do 1995 w Centrum Onkologii – Oddział w Krakowie u 120 chorych (36 kobiet, 84 mężczyzn) na chłoniaka nieziarniczego o pośrednim (76 chorych) lub wysokim (44 chorych) stopniu złośliwości zastosowano chemioterapię MACOP-B (24 chorych) lub VACOP-B (96 chorych). Stopień zaawansowania klinicznego przedstawiał się następująco: I-7 chorych (5,8%), II-18 chorych (15%), III-41 chorych (34,2%), IV-54 chorych (45%). Objawy ogólne (B) stwierdzono u 38 chorych (31,7%). U 103 chorych (85,8%) określono Międzynarodowy Wskaźnik Rokowniczy: 8 chorych (7,8%) znalazło się w grupie niskiego ryzyka, 34 chorych (33%) – w grupie średniego/niskiego, 32 chorych (31,1%) – w grupie średniego/wysokiego, a 29 chorych (28,2% w grupie wysokiego ryzyka. U 37 chorych (30,8%) chemioterapia skojarzona była z radioterapią. Stosowana dawka wahała się od 10 do 50 Gy (mediana 36 Gy). Po przeprowadzonym leczeniu u 84 chorych (70%) uzyskano całkowitą, a u 25 chorych (20,8%) częściową regresję choroby.W analizowanej grupie 120 chorych uzyskano następujące odsetki 5 letnich przeżyć: całkowitego u 45,7% chorych i bez nawrotu chłoniaka u 38,4% chorych. W trakcie obserwacji u 65 chorych (54,2%) stwierdzono rozwój niepowodzenia, które miało charakter wznowy, progresji klinicznej lub histopatologicznej. U 3 chorych stwierdzono rozwój drugiego nowotworu: raka żołądka, raka odbytnicy, ziarnicę złośliwą.Przeprowadzona analiza wpływu czynników prognostycznych na wyniki leczenia wykazała, że niezależnymi istotnymi statystycznie czynnikami prognostycznymi wykazującymi negatywny wpływ na wyniki leczenia w grupie chorych, u których zastosowano leczenie skojarzone są: lokalizacja pozawęzłowa, podanie niepełnego leczenia chemicznego, obniżona wartość hematokrytu, podwyższony odsetek limfocytów oraz podanie niższej dawki. Natomiast w grupie chorych, którzy otrzymali wyłącznie chemioterapię takimi czynnikami są: podwyższone stężenie dehydrogenazy mleczanowej, lokalizacja pozawęzłowa, niepełne leczenie chemiczne.U chorych, u których zastosowano radioterapię uzyskano wyższy odsetek przeżyć bez nawrotu chłoniaka w porównaniu z grupą leczoną wyłącznie chemioterapią. Szczególnie dotyczy to chorych w wyższym stopniu zaawansowania (III-IV) oraz z obecnością dużej masy nowotworu (bulky disease)