Cell type dependent effectiveness of tumour cell inactivation by radiation with increased ionisation density

Radiation with increased ionization density, LET, will in the near future be applied in targeted radiotherapy and has already, to some degree, been applied in external radiotherapy with accelerated ions. There are indications from the literature that different types of cells are sensitized differently when the LET is increased. Radiation with three different ionisation densities was applied in the present study; 0.8 keV/microns photons from a reference 60Co source, 6 keV/microns helium ions from the entrance region of a monoenergetic helium ion beam and 25 keV/microns from a range modulated helium beam. Three types of cultured cells were analysed: human colon carcinoma LS-174T, human glioma U-343MG and hamster embryonic lung V79-379A. There were interesting differences between the cell types; the LS-174T cells showed strong sensitization already at an LET of 6 keV/microns and there was nearly no difference between the shape of the survival curves after irradiation with 6 or 25 keV/microns. The V79-379A cells were less sensitive to the 6 keV/microns radiation quality and the survival curve was, in this case, very similar to the reference 60Co survival curve. However, the V79-379A cells were sensitized when exposed to the 25 keV/microns helium ions. The U-343MG cells were intermediate in the sense that the 6 keV/microns curve fell in between the 60Co and the 25 keV/microns curves. These variations indicate that different types of cells react differently to changes in LET and that this is probably of special interest for intermediate LET radiation. Some cells might be easily sensitized by intermediate LET qualities while others might be more resistant and this is of importance for the future optimization of radiation treatment with both targeted agents and accelerated ions.

New and simplified vaginal approach for correction of urinary stress incontinence in women

Twenty-four patients with urodynamically confirmed urinary stress incontinence were operated upon with a new and simplified vaginal approach. This new technique is a simplification of a previously described transabdominal surgical method, in which a two-component fibrin sealant (Tisseel) was used. The sealant resulted in an excess of fibrin, which induced fibrosis, securing the urethrovesical junction in an elevated position to the retropubic periosteum. In the present study, the sealant was deposited retropubically with a specially designed needle through the anterior vaginal wall. A great advantage with this procedure is that only local anesthesia is used and the patient can leave the outpatient clinic 1 hour after the operation. The minimum duration of the follow-up period was 18 months. The success rate was as high as 63%, and no side effects were observed.

Nitric oxide pathway in cat esophagus: localization of nitric oxide synthase and functional effects

In the cat lower esophageal sphincter (LES) and esophageal body, nitric oxide synthase (NOS) immunoreactive nerves were abundant in the circular smooth muscle layer, especially in the LES region. NADPH diaphorase staining showed an identical pattern. The ability to form L-citrulline from L-arginine corresponded roughly to the distribution of NOS. Confocal microscopic analysis indicated colocalization within neurons of vasoactive intestinal peptide (VIP) in 65% of NOS-positive nerves. In LES circular smooth muscle preparations, electrically induced relaxations (single train stimuli) were generally abolished by NG-nitro-L-arginine (L-NNA). Continuous electrical stimulation for 2 min evoked a relaxation in the presence of L-NNA. This relaxation was inhibited by VIP antiserum and followed by a decrease in guanosine 3',5'-cyclic monophosphate, but not by any consistent change in adenosine 3',5'-cyclic monophosphate levels. K+ (124 mM) induced a biphasic relaxation, with L-NNA inhibiting the first phase but not the second. We conclude that nitric oxide (NO) has a major role as the mediator responsible for relaxation in the cat esophagus. NO seems also to initiate the release and enhance the effect of another transmitter.

Nitric oxide synthase-containing, peptide-containing, and acetylcholinesterase-positive nerves in the cat lower oesophagus

The innervation of the cat lower oesophagus, including the lower oesophageal sphincter, was studied by enzyme histochemistry, immunohistochemistry, and confocal microscopy. In the lower oesophageal sphincter, and at a level 2 cm above it, no apparent differences were seen in the nerve distribution pattern. Among the nerve populations studied, acetylcholinesterase (AChE)-positive nerves were the most abundant in both these regions. The density of AChE-positive nerves was particularly marked in the circular muscle layer. A rich supply of nitric oxide synthase (NOS)-containing nerves was identified by using an antiserum against neuronal NOS, or by enzyme histochemical staining for NADPH diaphorase activity. Vasoactive intestinal peptide (VIP)-immunoreactive nerves had a similar distribution pattern as NOS-immunoreactive nerves, and nerves displaying immunoreactivity for NOS and VIP often showed profiles coinciding with AChE-positive nerves. As judged by confocal microscopy, immunoreactivities for helospectin, pituitary adenylate cyclase-activating peptide (PACAP) and VIP, to a large extent were found in the same nerves. At a level 7 cm above the lower oesophageal sphincter, the total nerve supply was less than in the sphincter itself and 2 cm above it. Immunoreactivity towards VIP, PACAP and helospectin was also found to co-exist with NOS and neuropeptide Y within the same nerve structures. It is concluded that there is an intricate innervation pattern in the feline lower oesophagus reflecting the complexity in the regulation of its motility.

The natural history of obesity in an obese population and associations with metabolic aberrations

The natural history of obesity was examined in a nation-wide sample of 1,084 obese men and 1,367 obese women aged 37-59 years who were recruited into a registry of potential subjects for an intervention trial. The registry and intervention studies are jointly referred to as SOS ('Swedish Obese Subjects'). In the registry, the mean body mass index was 37.7 kg/m2 in men and 40.9 kg/m2 in women. Descriptive information on subjects' weight histories and the relative weights of their biological parents was collected by means of a self-administered questionnaire. At a physical examination shortly thereafter, weights, heights and selected cardiovascular risk factors were measured in the fasting state. Virtually all subjects reported weight loss attempts in the past, men and women reported having gained weight during adulthood at a considerably higher rate than that observed in population-based samples. Significant correlations were observed between relative weights of obese males and both of their biological parents, but not between obese women and either of their parents. Indices of medical risk were then examined in relation to individual weight histories. Familial predisposition did not relate to most aspects of current medical risk. However, later-onset obesity tended to be associated with greater cardiovascular risk, while prior weight loss was predictive of an improved risk factor profile. These latter associations were not dependent on a subject's current degree of obesity and were particularly consistent with respect to fasting insulin level.

Studies of enteric pathogens and gamma-globulin levels of neonatal calves in Sweden

Faecal and blood samples were taken from 10-30% of calves, 36 hours to 14 days old, in 47 dairy herds in different regions of Sweden from September 1987 to October 1988 (Olsson et al. 1993). Faecal samples from 279 calves were analysed for the presence of Escherichia coli (K99+), rotavirus and Cryptosporidium sp. Twenty (7.2%) of these samples were from diarrhoeic calves. An ELISA was developed and used for the rotavirus analysis. E. coli K99+ was detected in 11.5%, Cryptosporidium sp. in 6.1% and rotavirus in 5.4% of the faecal samples. The presence of rotavirus alone and the combination rotavirus and E. coli (K99+) was found to be associated with diarrhoea (p < 0.001 and p < 0.01 respectively). Blood samples from 327 calves were analysed for the level of total protein and gamma-globulin. In 43 of these samples (13%) gamma-globulin did not separate from the beta 2-region by electrophoresis. The mean total protein concentration was 53.6 g/l in calves free from diarrhoea. The mean gamma-globulin concentration, adjusted to 7 days age was 5.9 g/l. The 20 diarrhoeic calves had lower levels of both total protein and gamma-globulin, compared with calves without diarrhoea, but the difference was not significant. One litre more of colostrum at the first feed increased the level of total protein of the calves' sera by 1.4 g/l (p = 0.05). Calves born between May and September had a 2.0 g/l higher (p < 0.001) serum concentration of gamma-globulin than calves born between October and April.

A serum-free, cell-free culture system for development of bovine one-cell embryos up to blastocyst stage with improved viability

With the aim of developing a serum-free, cell-free culture system for embryo development, in vitro-matured (IVM) and -fertilized (IVF) bovine oocytes were cultured in TCM 199 with the following supplements: 1) BSA alone (10 mg/ml); 2) BSA with ITS (5 mug/ml insulin, 5 mug/ml transferrin and 5 ng/ml selenium; BSAITS medium); 3) estrous cow serum alone (ECS; 10%); or 4) ECS with BOEC (bovine oviduct epithelial cells) (Experiment 1). In Experiment 2, embryos were cultured in BSAITS medium with or without feeding with fresh medium on Day 4 (day of insemination = Day 0). Embryos were evaluated on Day 2 for first cleavage, on Day 7 for morulae and blastocysts, and on Day 8 for blastocysts. Blastocysts from Experiment 1 were frozen in 10% glycerol in PBS, thawed and further cultured in ECS medium with BOEC for 48 h, and evaluated for formation of a distinct blastocoel, or expansion and hatching of blastocysts. In vivo-developed, Grade-1 and Grade-2, 7-d-old embryos served as control for the freezing, thawing and subsequent culture procedures. The percentage of first cleavage did not differ between the treatments (74 to 79% in Experiment 1 and 80 to 83% in Experiment 2). The percentage of blastocysts developed in BSAITS medium did not differ from that in ECS medium whether BOEC were present or not. However, medium with BSA alone had fewer blastocysts than any other culture system (P<0.05). Feeding embryos with fresh BSAITS medium on Day 4 did not lead to any further increase in the proportion of blastocysts. The culture systems had a significant effect on the post-thaw viability of blastocysts developed in them (P<0.001). Blastocysts developed in BSAITS medium had better (P<0.05) viability (14/38) than those from medium with ECS alone (1/27) or with ECS and BOEC (3/37). The post-thaw survival of control embryos was 80% (n=30). One of the three transfers of BSAITS-treated, frozen-thawed blastocysts resulted in a pregnancy. The results indicate that a serum-free, cell-free culture system can support the development of IVM-IVF bovine oocytes up to the blastocyst stage with better viability than a complex co-culture system.

Cytotoxic susceptibility and defective MHC class I expression do not correlate with mutation of p53 in human carcinomas

Twenty-nine samples of ex vivo ovarian and lung carcinomas were investigated for the relationship between the presence of mutated protein 53 (mp53) and cytotoxic susceptibility. Unaltered expression of MHC class I alleles was required for the cytotoxic susceptibility of tumour cells to the autologous ex vivo blood lymphocytes, i.e. all 4 sensitive tumours belonged to the group of 11 tumours without defect in MHC class I expression. In contrast, the susceptibility did not correlate with the presence of mp53, i.e. cases with mp53 were randomly distributed between the sensitive and resistant tumours (2/4 and 10/17 respectively). There was no correlation either between the p53 mutation and down-regulation of MHC class I alleles. The results suggest that in these tumours the mutated p53 is not the source of immunogenic peptides and that the lack of recognition of the tumours with mp53 is not caused by a defect in the expression of MHC class I molecules.

Survival rate and ultrastructure of vitrified bovine in vitro and in vivo developed embryos

The capacity of different vitrification media and methods was tested onto in vivo and in vitro produced bovine morula/blastocysts and their ultrastructure and survival studied post-thawing. Two vitrification solutions were finally selected, named 40 ES (40% ethylene glycol in PBS containing 0.5 M sucrose) and 35 EFS (composed of 35% (v/v) ethylene glycol in PBS containing 0.5 M/l sucrose and 30% (w/v) Ficoll 70). The straws were either precooled or not precooled in nitrogen vapour, plunged and stored in LN2 for 10-25 days, and then thawed in a 20 degrees C waterbath. The content of the straws was rediluted in 1M sucrose solution in PBS and later cocultured with BOEC for 48 h. The overall survival rates for in vitro and in vivo embryos were 36% (12 of 33) and 20% (3 of 15) after 24 h and 21% (7 of 33) and 33% (5 of 15) after 48 h. The survival rates for precooled embryos were significantly higher than for not precooled (48% vs 13% after 24 h and 44% vs 4% after 48 h) when tested across vitrification media. The in vitro-produced embryos presented an ultrastructure similar to the pre-freeze state, irrespective of the vitrification media used. The in vivo developed embryos showed a rather modified post-thaw ultrastructure, with clear signs of osmotic changes at both the trophoblastic and embryonic cells. The results indicated that in vitro and in vivo developed bovine embryos can survive vitrification using ethylene glycol as a cryoprotectant.

The role of the L-arginine/nitric oxide pathway for relaxation of the human lower oesophageal sphincter

Smooth muscle specimens were taken from the oesophagogastric junction (OGJ) in patients operated on for gastrointestinal malignancies not involving the OGJ. The smooth muscle bundles of the inner, circular layer of the OGJ were richly innervated by fine nerve fibres staining positively for NADPH diaphorase. The outer longitudinal layer had a markedly lower number of NADPH-diaphorase positive nerve fibres. When the preparations were suspended in organ baths for recording of isometric tension, they developed active tension. Transmural field stimulation (TMS) induced frequency-dependent relaxations, which were abolished by NG-nitro-L-arginine (L-NNA; 10(-4) M), and were often converted to atropine-sensitive contractions. The effect of L-NNA was concentration-dependent, and the concentration-response curve for L-NNA was shifted to the right by L-arginine pre-incubation. The enantiomer NG-nitro-D-arginine (10(-4) M) also showed inhibitory actions on the responses to TMS, but significantly less than L-NNA. Relaxant responses to vasoactive intestinal polypeptide (VIP), forskolin, and sodium nitroprusside were unaffected by L-NNA pre-incubation. Exposure to a 124 mM K+ solution resulted in a biphasic relaxation of the preparations. This relaxation was not seen in preparations treated with scorpion venom (20 micrograms ml-1) or L-NNA (10(-4) M). Instead, a contractile response to 124 mM K+ solution was found. The results suggest that NANC responses to electrical stimulation of nerves in the human OGJ are mediated by a product generated from L-arginine.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravesical instillation of terodiline--an in vivo study of drug absorption in rabbit and man

The absorption of intravesically administered terodiline was investigated in 8 healthy volunteers (10(-4)) and in 33 rabbits (10(-4)) M., 4 X 10(-4) M. and 1.6 X 10(-3) M.). In the humans, the amount of drug retained and the serum concentration were registered. In the rabbits, the influence of drug concentration, pH (5 and 9.2) and volume (5 and 20 ml.) were evaluated. Liquid scintigraphy of the bladder wall and of serum and tissue samples from striated muscle, kidney and liver was performed. Further, autoradiography of the bladder wall and calculation of drug retention were done. In the humans, 20 +/- 5% of the administered terodiline dose was retained in the body. Clinically significant serum concentrations were not detected. In the rabbits, 21 +/- 4% of the drug was retained with the pH = 5 terodiline solution as compared with 64 +/- 3% with the pH = 9.2 solution. With increasing terodiline concentrations, drug retention increased, as did the tissue and serum activities. At a given concentration, the total amount of drug retained increased with a larger volume. The drug gradient between the bladder muscle layer and serum was of a magnitude of about 100, independent of the drug concentration within the muscle layer. It is concluded that the pH and concentration of the solution are factors of major importance for the amount of terodiline absorbed from the bladder. Compared with the one obtainable by systemic drug administration, the large gradient between the bladder muscle and the serum is conspicuous, and may be of clinical interest.

Immunofixation superior to plasma agarose electrophoresis in detecting small M-components in patients with polyneuropathy

Monoclonal immunoglobulins (M-components) in blood are found in some patients with polyneuropathy and are thought to be of pathogenetic importance, especially if the M-component is of IgM isotype. As the finding of an M-component may indicate a treatable polyneuropathy, the potential of the method to uncover an M-component is of importance. Cellulose acetate or agarose electrophoresis used in routine practice may miss small M-components covered by other proteins. We therefore applied the uncovering and specific method of immunofixation in comparison with agarose electrophoresis on patients investigated for polyneuropathy. Of 83 consecutive patients, 5 had M-components. Two of these 5 patients, one with an axonal polyneuropathy and the other with a lower motor neuron syndrome, had extra bands on agarose electrophoresis, verified as IgG M-components by immunofixation. In the 3 additional patients an M-component was uncovered only by immunofixation, not seen in the agarose electrophoresis of plasma; 2 of them were of IgM isotype and one was of IgG isotype. These 3 patients were diagnosed as having a demyelinating (i.e., possibly immune-mediated) polyneuropathy by means of neurophysiology and in one by means of nerve biopsy. A 6th patient had 2 small bands in the gamma region on the agarose electrophoresis, verified as oligoclonal bands of IgG isotype by immunofixation but was not judged as an M-component. Three out of the 83 patients, were judged as having motor neuron diseases. All remaining 80 were found to have polyneuropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitric oxide synthase in pig lower urinary tract: immunohistochemistry, NADPH diaphorase histochemistry and functional effects

1. The distribution and colocalization of nitric oxide synthase (NOS)-like immunoreactivity and NADPH diaphorase activity in the pig lower urinary tract were investigated by immunohistochemical and histochemical staining techniques. Functional in vitro studies were performed to correlate the presence of NOS-immunoreactivity/NADPH diaphorase staining with smooth muscle responses involving the L-arginine/nitric oxide (NO) pathway. 2. NOS-immunoreactivity and NADPH diaphorase activity were expressed in nerve trunks and fine nerve fibres in and/or around muscular bundles in the detrusor, trigone and urethra. Thin nerve fibres that dispersed within the muscle bundles were mainly found in the urethral/trigonal area, whereas such fibres were less common in the detrusor. 3. Almost all neuronal structures that were NOS-immunolabeled were also stained for NADPH diaphorase. In contrast, the urothelium, which was intensively stained by the NADPH diaphorase technique, remained unstained by immunohistochemistry. 4. Electrical field stimulation of pig isolated trigonal and urethral preparations induced relaxations, which were inhibited by tetrodotoxin (1 microM) and NG-nitro-L-arginine (L-NOARG, 10 microM). 5. L-Arginine (1 mM), but not D-arginine, inhibited (25-30%) electrically evoked detrusor contractions. This inhibition was reversed by L-NOARG (0.1 mM). L-Arginine did not inhibit detrusor contractions in the presence of scopolamine (1 microM) and had no direct smooth muscle effects per se. 6. Acetylcholine (1 nM-10 microM) caused concentration-dependent relaxations of noradrenaline-induced contractions in pig vesical arteries. Removal of the endothelium practically abolished the acetylcholine-induced relaxation. Pretreatment with L-NOARG (0.1 mM and 0.3 mM) caused a rightward shift of the concentration-response curves to acetylcholine, but the maximal relaxation obtained was significantly reduced (to 65 +/- 12%; n = 6; P < 0.05) only at 0.3 mM L-NOARG. 7. In vessel segments contracted with K+ (60 mM), acetylcholine induced concentration-dependent relaxations. When the vessels were incubated with 0.3 mM L-NOARG and then contracted with K+ (60 mM) all relaxant responses to acetylcholine were abolished. 8. The presence of NO synthesizing enzyme in nerve fibres and the pharmacological evidence for NO-mediated relaxation of the trigone and urethra suggest that NO or a NO-related substance may have a role in inhibitory neurotransmission in these regions. In the detrusor, the presence of NO-synthesizing enzyme in nerves can be demonstrated, but its functional importance is unclear. NO, as well as other endothelium-derived factors seem to be involved in the endothelium-dependent acetylcholine-induced relaxation of pig vesical arteries.

Winter dysentery diagnosed by farmers in dairy herds in central Sweden: incidence, clinical signs and protective immunity

The occurrence of winter dysentery, diagnosed by farmers and defined as an outbreak of diarrhoea among at least 30 per cent of adult cattle in a herd, was monitored in 256 dairy herds in an area of central Sweden. The cumulative incidence of winter dysentery between April 1988 and March 1989 was 28.5 per cent. A typical outbreak lasted for one to two weeks and 74 per cent of the outbreaks occurred between November and January. A decrease in milk yield was reported in 90 per cent of the affected herds and the cows showed respiratory signs in 57 per cent of them. There was a significant (P < 0.05) association between the occurrence of fever and coughing. In 31 per cent of the outbreaks the farmer also noticed diarrhoea among the calves. One-third of the affected herds had experienced an outbreak within the previous four years and 18 per cent had at least one further outbreak during the following two years. There was a significantly (P < 0.05) lower disease score in herds that had had an outbreak within the previous four years than in herds which had had a less recent or no previous outbreak, indicating the development of temporary immunity to the causative agent.

Swedish obese subjects (SOS)--an intervention study of obesity. Baseline evaluation of health and psychosocial functioning in the first 1743 subjects examined

This part of an on-going intervention trial analyses impacts of obesity on psychosocial factors and health. The study sample comprised 800 obese men (BMI > or = 34 kg/m2) and 943 women (BMI > or = 38 kg/m2) ranging in age from 37 to 57 years. All participants completed standardized health-related quality of life measures, a validated obesity-specific eating inventory and study-specific questionnaires on current and past health status, use of medical care and medications, socioeconomic status, dietary habits, physical activity habits, weight history and familial history of obesity. Chronic patients and population samples were used as reference. The obese reported distinctly poorer current health and less positive mood states than the reference subjects, women being worse than men. Anxiety and/or depression on a level indicating psychiatric morbidity were more often seen in the obese and again women reported more affliction than men. Furthermore, the average poor mental well-being was worst than in chronically ill or injured patients, such as rheumatoid, cancer survivors and spinal cord injured persons. Predictors of perceived health and psychosocial functioning could be discerned using a comprehensive system of statistical analyses (16-28% explained variance). A background of both somatic and psychiatric morbidity was decisive for the health and psychosocial functioning in the obese; joint symptoms and angina pectoris dominated among somatic variables. Physical inactivity was the most prominent of traditional risk factors. The number of dieting attempts and body image were important weight correlates. Our results provide further evidence to the effect that severe obesity is a crippling condition.

A facility for biomedical experiments with thermal neutrons

The Studsvik thermal-neutron facility was originally designed for neutron capture radiography (NCR) at high thermal-neutron fluence and low fast-neutron contamination. It has now been modified to permit irradiation of living cells and animals without the need for stopping and restarting the R2-0 reactor. Previous calculations of the thermal-neutron intensity at the NCR position were performed using the two-dimensional diffusion theory code DIXY. In this report the Monte Carlo program MCNP 3B is used to calculate the neutron fluence at the radiography position, and neutron and photon fluences at the positions of the cell specimens. The normalized neutron fluences from the calculations agree well with measured values and show that the contamination with high-energy neutrons is low. The agreement between measured and calculated photon doses was reasonable. The thermal-neutron fluence rate is (2.3 +/- 0.1) x 10(9) cm-2 s-1 at 100 kW at the NCR position and (0.96 +/- 0.03 x 10(9) cm-2 s-1 at 100 kW at the front plate of the loading tube. The photon dose is about (1.6 +/- 0.2) x 10(-12) Gy per neutron. Survival curves of V79 cells grown as monolayers and irradiated in the thermal neutron beam, with and without boron, are presented.

Immunohistochemical localization of peripheral nitric oxide synthase-containing nerves using antibodies raised against synthesized C- and N-terminal fragments of a cloned enzyme from rat brain

Antibodies were raised in rabbits against C- or N-terminal fragments of a cloned nitric oxide synthase (NOS) enzyme from rat cerebellum, and used for demonstration of NOS-immunoreactive (NOS-IR) nerves in different tissues from the rat (colon, duodenum, adrenal gland, aorta, caval vein, penis and urethra). Both antisera demonstrated the same neuronal elements, although with differences in intensity in the immunoreaction in some tissues. Sections incubated with antisera preabsorbed with excess of the antigens showed no NOS immunoreactivity. In duodenum and colon, NOS-immunoreactivity was found in the cytoplasm of numerous cell bodies in myenteric ganglia and in some nerve cell bodies in the submucosa. NOS-IR nerve fibres were numerous in the circular muscle layer, while few were found in the longitudinal layer or the mucosa and submucosa. In the penis, strong NOS immunoreactivity was found in nerves surrounding the deep penile and dorsal arteries, and in nerves in the stroma of the cavernous tissue. In the urethra, NOS immunoreactivity was found in nerves in the mucosa. No NOS immunoreactivity was found in the urothelium. The adrenal medulla, and occasionally the cortex, contained nerve cell bodies with strong cytoplasmic NOS immunoreactivity as well as scattered nerve fibres. No NOS immunoreactivity was found in the abdominal aorta or inferior caval vein. Combined NOS immunostaining and NADPH diaphorase staining showed that virtually all NOS-IR nerve structures were also NADPH diaphorase-positive. However, thin nerve fibres and cell linings were sometimes better visualized by NOS-immunohistochemistry. Furthermore, the adrenal cortex, which only occasionally showed NOS immunoreactivity, was strongly NADPH diaphorase-positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative neutron capture radiography for boron in biological specimens

Track-etch detectors made of cellulose nitrate (LR 115, Kodak Pathé) and polycarbonate (CR 39, Pershore Mouldings Ltd) were compared regarding sensitivity and background when used as detectors for boron determination in biological samples. Measurements were made on two kinds of sample, cryosectioned biological tissue, and liquid samples deposited directly on the detector surface as microdroplets. The CR 39 films were pretreated or washed before irradiation. When cryosectioned tissue was used, measurements were made with and without the inclusion of Mylar foils between the samples and the detectors. Foil thicknesses used were 2 microns in the case of LR 115 and 2, 4, and 6 microns in the case of CR 39. All samples were irradiated with a thermal-neutron fluence of 5 x 10(12) neutrons cm-2 at the thermal-neutron facility in Studsvik, Sweden. The use of a Mylar foil generally suppressed the background tracks relative to the tracks from the 10B disintegration. No difference in resolution between CR 39 and LR 115 was observed. Pretreatment of the CR 39 resulted in an improved sensitivity of detection but the detector became saturated at 0.25 parts per million of 10B. The background was found to be lower in the pretreated detector.

The L-arginine/nitric oxide pathway in the rabbit urethral lamina propria

A non-adrenergic, non-cholinergic (NANC)-mediated relaxation has been demonstrated in the female rabbit urethral lamina propria, both in response to electrical stimulation and after administration of acetylcholine. The present study was performed to investigate if these relaxations are mediated via the L-arginine/nitric oxide (NO) pathway. In the lamina propria of the female rabbit urethra, numerous NADPH diaphorase-positive, fine varicose nerve fibres were observed both around arteries, in and around smooth muscle bundles, and in arterial endothelium. Since NADPH diaphorase histochemistry may be a marker of NO synthase-containing neurons, this finding suggests the occurrence of NO synthase in this tissue. Isolated preparations of the rabbit urethral lamina propria, contracted by noradrenaline, produced frequency-dependent NANC relaxations in response to electrical field stimulation, and concentration-dependent NANC relaxations in response to acetylcholine. Electrically induced relaxations were possible to evoke even in preparations where acetylcholine-induced relaxation was poor or absent. Pretreatment with the NO synthase inhibitor, NG-nitro-L-arginine (L-NOARG) reduced the maximum relaxation obtained at 30 Hz to 12% of the control response. NG-nitro-D-arginine (D-NOARG) had no effect. The effects of L-NOARG were antagonized by the addition of L-arginine. Acetylcholine relaxed noradrenaline-precontracted strips by 36%; vasoactive intestinal polypeptide (VIP) reduced the contraction by 95%. L-NOARG, but not D-NOARG, abolished or reversed acetylcholine-induced relaxations, but failed to reduce the relaxations produced by VIP. The results demonstrate the occurrence of NADPH diaphorase-positive nerve fibres in the lamina propria of the female rabbit urethra.(ABSTRACT TRUNCATED AT 250 WORDS)