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Biomedical subjects

S Held

Publications and source records attributed to S Held.

14 recordsLinked to original sources
PubMed2006

Factors associated with preweaning mortality on commercial pig farms in England and Wales.

Data from 67 pig farms with a variety of farrowing systems were used to identify factors associated with preweaning mortality in British pig herds. The median mortality reported by the farmers was 10.7 per cent (interquartile range 8.5 to 14 per cent). There was a significantly higher mortality when the pigs were weaned when they were older. A multivariable Poisson model was developed into which the types of farrowing system on each farm and the age at weaning were forced. Factors associated with a lower preweaning mortality rate were insulating the farrowing building, providing extra heat at farrowing, giving the piglets iron injections, dipping their navels, using fan ventilation and using artificial lighting systems. Factors associated with a higher mortality rate were a later weaning age, the use of infra-red lamps rather than other forms of supplementary heat, and the use of a creep without any bedding.

Animal Husbandry↗
PubMed2004

Foraging behaviour in domestic pigs (Sus scrofa): remembering and prioritizing food sites of different value.

This experiment investigated whether domestic pigs can remember the locations of food sites of different relative value, and how a restricted retrieval choice affects their foraging behaviour. Nine juvenile female pigs were trained to relocate two food sites out of a possible eight in a spatial memory task. The two baited sites contained different amounts of food and an obstacle was added to the smaller amount to increase handling time. On each trial, a pig searched for the two baited sites (search visit). Once it had found and eaten the bait, it returned for a second (relocation) visit, in which the two same sites were baited. Baited sites were changed between trials. All subjects learnt the task. When allowed to retrieve both baits, the subjects showed no preference for retrieving a particular one first (experiment 1). When they were allowed to retrieve only one bait, a significant overall preference for retrieving the larger amount emerged across subjects (experiment 2). To test whether this preference reflected an avoidance of the obstacle with the smaller bait, 15 choice-restricted control trials were conducted. In control trials obstacles were present with both baits. Pigs continued to retrieve the larger bait, indicating they had discriminated between the two food sites on the basis of quantity or profitability and adjusted their behaviour accordingly when the relocation choice was restricted. This suggests for the first time that domestic pigs have the ability to discriminate between food sites of different relative value and to remember their respective locations.

Animals↗
PubMed2003

[Atypical resting ecg pattern in a patient with a positive family history of sudden cardiac death]].

A 42 year old male patient presented with atypical ECG pattern at rest and reported that his brother died suddenly of unknown reasons at the age of 40. A performed pharmacological testing with ajmalin discovered strong ST-segment elevations in lead V(1) and V(2) in combination with an incomplete right bundle branch block. As a result, the diagnosis Brugada syndrome was established. The Brugada syndrome is a primary cardiac conduction disturbance without structural heart disease and is associated with an increased risk of sudden cardiac death caused by life threatening ventricular tachyarrhythmia. It is an inherited disease displaying an autosomal dominant mode of transmission with an incomplete penetrance, especially prevalent in females. In some regions like the southeast of Asia and Japan it is endemic. The mutation is linked to the sodium channel gene SCN5A. The annual mortality rate is estimated 30 per 100.000 persons. Today, exact diagnostic criteria do not exist. The diagnosis is based on the typical ECG pattern, combined with clinical symptoms, and a family history of sudden cardiac death. The currently suggested therapy consists of the implantation of an internal defibrillator.

Adult↗
PubMed2002

Biocompatibility tests on the intraocular vision aid IOVA.

Intraocular miniaturized image transmission systems are developed to restore vision in patients with irreversible destruction of the anterior ocular segment (i.e. chemical burns, explosion trauma, trachoma) and high risk for corneal transplantation, provided that the posterior ocular segment is intact. To ensure safety of such a device biocompatibility tests were conducted. In the present study the effects of light and temperature in various intensities and the toxicity of the implanted materials on neural function in the rabbit retina in-vivo was investigated. All tests give encouraging results concerning the feasibility of intraocular miniaturized image transmission systems.

Animals↗
PubMed2000

Social tactics of pigs in a competitive foraging task: the 'informed forager' paradigm.

Studies of the social dynamics in foraging groups have focused primarily on birds, rodents and nonhuman primates. We extended the study of animal social tactics to the domestic pig, Sus scrofa, by using an experimental analogue of natural foraging skills, the 'informed forager' paradigm. We investigated the behaviour of 16 pigs foraging in pairs in an arena in which food had been hidden in one of eight monopolizable buckets. Before each pair trial, one of the pigs, the 'informed' pig, was given privileged knowledge about the location of the food during a solitary search trial. The 'noninformed' pig was naïve about the location of the food during pair trials, but heavier than its informed partner and thus able to displace the latter from the baited bucket. By first focusing on the informed pigs' behaviour, we show that pigs are able to remember and relocate the food site. They found the food in relocation trials, using fewer bucket investigations than expected of a random searcher. Second, by focusing on the noninformed pigs, we show that pigs are able to exploit the knowledge of others by following them to a food source. They investigated more buckets immediately after their informed partners significantly more often than expected by chance and required fewer bucket investigations to find the food in pair trials than expected from a random searcher, but not in solitary search trials. We discuss these latter findings with reference to social foraging tactics. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Ethylnitrosourea-induced development of malignant schwannomas in the rat: two distinct loci on chromosome of 10 involved in tumor susceptibility and oncogenesis.

Inbred rodent strains with differing sensitivity to experimental tumor induction provide model systems for the detection of genes that either are responsible for cancer predisposition or modify the process of carcinogenesis. Rats of the inbred BD strains differ in their susceptibility to the induction of neural tumors by N-ethyl-N-nitrosourea (EtNU). Newborn BDIX rats that are exposed to EtNU (80 microg/g body weight; injected s.c.) develop malignant schwannomas predominantly of the trigeminal nerves with an incidence >85%, whereas BDIV rats are entirely resistant. A T:A-->A:T transversion mutation at nucleotide 2012 of the neu (erbB-2) gene on chromosome 10, presumably the initial event in EtNU-induced schwannoma development, is later followed by loss of the wild-type neu allele. Genetic crosses between BDIX and BDIV rats served: (a) to investigate the inheritance of susceptibility; (b) to obtain animals informative for the mapping of losses of heterozygosity (LOH) in tumors with polymorphic simple sequence length polymorphisms (SSLPs); and (c) to localize genes associated with schwannoma susceptibility by linkage analysis with SSLPs. Schwannoma development was strongly suppressed in F1 animals (20% incidence). All of the F1 schwannomas displayed LOH on chromosome 10, with a consensus region on the telomeric tip encompassing D10Rat3, D10Mgh16 and D10Rat2 but excluding neu. A strong bias toward losing the BDIV alleles suggests the involvement of a BDIV-specific tumor suppressor gene(s). Targeted linkage analysis with chromosome 10 SSLPs in F2 intercross and backcross animals localized schwannoma susceptibility to a region around D10Wox23, 30 cM centromeric to the tip. Ninety-four % of F1 tumors exhibited additional LOH at this region. Two distinct loci on chromosome 10 may thus be connected with susceptibility to the induction and development of schwannomas in rats exposed to EtNU.

Animals↗
PubMed1996

Experiences with percutaneous endoscopic gastrostomy.

Today the procedure of choice for long-term enteral tube feeding in patients with prolonged swallowing difficulties or inabilities is percutaneous endoscopic gastrostomy (PEG). The primary indications are head and neck cancers, neurologic dysphagia, cancer cachexia, and obstruction of the esophagus and pharynx with enough space for an endoscopic procedure. This technique requires no general anesthesia and is possible in patients with contraindications to surgical gastrostomy. Between September 1994 and April 1995 a total of 115 patients underwent PEG placement attempts. We employed the pull-technique with 15-Freka PEG tubes. The average procedure time, including esophagogastroduodenoscopy, was 17 minutes. In nine cases PEG insertion was impossible owing to severe obstruction of the esophagus. In 46 (40%) patients local abdominal pains started on the first or second postoperative day; 7 of these patients required surgical consultation, and no further intervention was needed. In only one patient was there a serious complication that required surgical intervention: a presumed perforation that turned out to have no correlate upon review. All patients received single-shot antibiotic prophylaxis; and only in those patients with abdominal symptoms do we recommend a prolonged antibiosis. The abdominal symptoms reported were due to a slight leak of gastric fluid causing a topical peritonitis, which required no further treatment. In our experience PEG is a useful alternative to surgical gastrostomy. The simplicity of this procedure leads to low complication rates, short hospitalization, and is possible on an outpatient basis. It is cost-efficient and has a much better psychological tolerance than nasogastric tubes.

Adult↗
PubMed1996

[Instruments for gasless laparoscopic surgery].

Specially designed instruments for laparoscopic surgery with a pneumoperitoneum are expensive and delicate, and surgeons are initially not familiar with their handling. Beside restrictions of the surgeon's intraabdominal range of motion they lead to a loss of tactile sensation. In gasless laparoscopic procedures not only special laparoscopic instruments, but the standard conventional instruments, used in open surgery, can also be employed with simple valveless trocars. Still using these instruments can put up some difficulties, because ergonomic factors were not considered in their development. With regard to the instrument's length, shape and joint-position we developed a special instrument-set under the ergonomic criteria of gasless laparoscopy.

Equipment Design↗
PubMed1994

[Whiplash injury of the cervical spine--on the role of pre-existing degenerative diseases].

Radiological investigations contribute little in differentiating the problems of patients with whiplash injuries. Nevertheless the more prolonged cases of whiplash injuries must not be attributed to preexisting degenerative disease, despite radiologically-proven medicolegal opinion. In this study, 60 patients who were seen for whiplash injuries in the Department for Trauma and Reconstructive Surgery at the University Hospital Hamburg-Eppendorf for clinical and radiological evaluation, an average of 5.7 years post injury, were divided into two groups (n = 30) depending on radiologically-proven preexisting degenerative changes of the cervical spine. On average the patients with degenerative changes were 11.2 years older than those with healthy vertebral columns and also demonstrated an increase in acute symptoms in the lower cervical spine (cervicobrachial syndrome). The chronicity of individual symptoms such as neck-pain, dizziness, nausea and psychological illness was also observed in both groups. Problems such as paresthesias as well as pain in the shoulder-arm-area appeared to increase in subsequent check-ups, irrespective of the earlier degenerative changes. Patients with typical posterior headaches recovered faster when they had radiologically normal spines. Presenting late, there was a significant accumulation of patients with pre-existing degenerative changes complaining merely of tinnitus. The earlier changes in any individual motion segment do not determine the clinical course of whiplash injuries, but merely represent an area of increased vulnerability to trauma. On the other hand, trauma has not been proven to influence the development or aggravation of degenerative changes in normal or diseased spines. We are not able to differentiate the posttraumatic course from the natural history of the degenerative process, either clinically or radiologically. Considering the involvement of sensitive neurological structures the classical objective organic diagnosis of "whiplash injury" may not be adequate in describing the complaints of patients, and should not be used to justify the rejection of the patients subjective symptoms as mere simulation for financial gains. The evaluation of the patients' X-rays using Arlen's technique sheds no further light on the issue.

Accidents, Traffic↗
PubMed1990

Merbromin (mercurochrome)--a photosensitizer for singlet oxygen reactions.

Merbromin, produced in many countries and used world wide as an antiseptic under the trademark "mercurochrome", is shown to be an efficient sensitizer for type II (singlet oxygen) photo-oxygenations by using 2-methyl-2-butene, (+)-limonene, (+)-alpha-pinene, alpha,alpha'-dimethylstilbenes and (--)-L-methionine as oxygen acceptors. Type I photo-oxygenations are negligible. An estimate of the quantum yield of singlet oxygen formation by merbromin in methanol gives a value of about 0.1.

Cyclohexenes↗
PubMed1984

Evaluation of family stroke education.

To increase families' involvement in rehabilitation, a series of informational sessions called the Family Stroke Education Class was implemented at a 305 bed medical center serving disabled veterans and their families. Questionnaires completed by family and patients at the meetings showed that anxiety level decreased significantly. More than 90% of participants felt more comfortable about approaching team members with questions in the future, and 77% felt more informed as a result of taking the class. Knowledge scores improved significantly and sustained over a 3 month time period. The educational format was a practical way of including the needs and soliciting participation of the family as well as a means for providing basic information on stroke rehabilitation.

Aged↗
PubMed1982

Effects of polychlorinated biphenyls and environmental biotransformation products on aquatic nitrification.

The effects of polychlorinated biphenyls (PCBs) on nitrification were examined for pure cultures and natural reservoir samples. PCBs at concentrations greater than 10 microgram liter-1 inhibited nitrification, principally ammonium oxidation, in one of two natural reservoir environments. However, this inhibition could not be reproduced in pure high-cell-density cultures or in previously contaminated reservoir waters. A PCB environmental biotransformation product, p-chlorophenylglyoxylic acid, and p-chloromandelic acid had no effect on nitrification.

Biotransformation↗
PubMed1978

Poisoning of palm doves with dibutyltin dilaurate.

Dibutyltin dilaurate was inadvertently introduced into dairy feed which was consumed by wild palm doves (Streptopelia senegaleniss). About 150 dead and dying doves were found within several days. Extremely high concentrations of tin were found in samples of liver and skeletal muscle in these birds. A sample of the feed, which was found to contain about 2,500 ppm tin, was fed exclusively to 2 normal palm doves. On the 8th day of feeding, one dove died and the other was moribund. High concentrations of tin (27 to 141 ppm) were found in the livers of poisoned birds. Signs of poisoning in both the naturally occurring and experimentally induced poisonings were severe depression and yellow diarrhea.

Animal Feed↗