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Biomedical subjects

K Bergstrom

Publications and source records attributed to K Bergstrom.

15 recordsLinked to original sources
PubMed2002

Could automated template based quantification of benzodiazepine receptors in brain single photon emission tomography with 123I NNC 13-8241 be used to demonstrate neuronal damage in traumatic brain injury?

Automated methods are required for the analysis of brain single photon emission tomography images. We applied an automated method to assess the benzodiazepine receptor distribution in the brain. Images of 19 patients with mild traumatic brain injury who had received I NNC 13-8241 were compared with a mean brain template accumulated from 18 healthy volunteers. To obtain more information, we calculated the neuronal benzodiazepine receptor binding in the brain by using pre-defined anatomical regions and a voxel-by-voxel technique. The group of patients with mild traumatic brain injury differed significantly (P =0.015) from the group of healthy volunteers in the distribution of benzodiazepine receptors. This methodological work suggests that a reference based template and a three-dimensional brain model help in regional analysis and quantification and could be useful in demonstrating permanent neuronal damage after head injury.

Adolescent↗
PubMed2000

Highwire regulates synaptic growth in Drosophila.

The formation, stabilization, and growth of synaptic connections are dynamic and highly regulated processes. The glutamatergic neuromuscular junction (NMJ) in Drosophila grows new boutons and branches throughout larval development. A primary walking behavior screen followed by a secondary anatomical screen led to the identification of the highwire (hiw) gene. In hiw mutants, the specificity of motor axon pathfinding and synapse formation appears normal. However, NMJ synapses grow exuberantly and are greatly expanded in both the number of boutons and the extent and length of branches. These synapses appear normal ultrastructurally but have reduced quantal content physiologically. hiw encodes a large protein found at presynaptic terminals. Within presynaptic terminals, HIW is localized to the periactive zone surrounding active zones; Fasciclin II (Fas II), which also controls synaptic growth, is found at the same location.

Animals↗
PubMed2000

Growth factor usage patterns and outcomes in the community setting: collection through a practice-based computerized clinical information system.

PURPOSE: Although use of colony-stimulating factor (CSF) is widespread and guidelines for use have been disseminated, actual practice patterns of medical oncologists are unknown. The purpose of this study was to collect these data using an office-based computerized clinical information system. PATIENTS AND METHODS: Data were collected on patients at 10 community-based oncology practices. Information regarding CSF use was captured at the time of prescribing through a computerized clinical support tool and stored in a data warehouse, and an analysis was carried out retrospectively. RESULTS: A total of 6,813 cancer regimens administered to 5,034 patients were evaluated for growth factor use. Overall, CSFs were used in 14% of regimens, with breast, lymphoma, lung, and ovarian being the most common cancers for which CSFs were used. In 49.4% of regimens, CSF was initiated during cycle 1, with an average duration of 1 week, and was used in two or three cycles per regimen. Afebrile neutropenia is rarely followed by CSF initiation. Granulocyte colony-stimulating factor (G-CSF) is associated with fewer dose adjustments, delays, and hospitalizations when compared with granulocyte-macrophage colony stimulating factor (GM-CSF). There is wide variation among oncologists in CSF use, and several substantial differences were noted between the prescribing behavior of American Society of Clinical Oncology (ASCO) survey-reported oncologists and actual clinical practice, as captured by the computerized clinical information system. CONCLUSION: Computerized clinical information systems can collect detailed information regarding practice patterns of medical oncologists. ASCO physician practice survey data do not accurately reflect actual practice patterns and must be interpreted with caution. Substantial deviations from ASCO growth factor guidelines remain, and oncologists' use of CSFs demonstrates wide variation. There may be important clinical differences between G-CSF and GM-CSF, but definitive phase III trials are needed for confirmation.

Antineoplastic Agents↗
PubMed1990

Locus of information in words and the right visual field effect.

The right visual field (RVF) advantage found for the identification or classification of words has usually been interpreted as evidence for left hemisphere language functions. It has more recently been explained as the result of the fact that the most informative part of the word, presumably the beginning, is in a region of better visual acuity. It is not clear from existing evidence that the beginnings of words are in fact more informative. The present study assessed the locus of information in words by deleting either the initial or terminal one or two letters. Subjects were required to generate a completion. Regardless of whether subjects were scored as correct for generating the original target word (as would be appropriate in a naming study) or for producing any legitimate word (as would be appropriate for a lexical decision study), the results indicated that most words have more information in the initial letters. Nevertheless, there are exceptions to this rule, and some words have more terminal information. Equal numbers of words with more initial information and with more terminal information were selected for two visual field studies in order to assess the effect of the locus of information on visual laterality. In neither a lexical decision study nor a naming study did locus of information affect the commonly observed right visual field superiority. Thus the distribution of information is not likely to be a major confounding variable in laterality studies employing horizontally presented words.

Adolescent↗
PubMed1988

Potentiation of the gonadotoxicity of Cytoxan in the dog by adjuvant treatment with a luteinizing hormone-releasing hormone agonist.

This study evaluates the effect on spermatogenesis of coadministration of Cytoxan (cyclophosphamide) and nafarelin, a luteinizing hormone-releasing hormone agonist. Nafarelin causes complete aspermatogenesis in dogs by interrupting the hypothalamic-pituitary-gonadal axis, which might protect against the testicular cytotoxicity associated with cyclophosphamide. The four treatment groups, each consisting of 2 mature male beagle dogs, were (a) no drug; (b) cyclophosphamide (p.o. 3x weekly for 43 and 48 wk for a total dose of 582 and 709 mg/kg, with dose varying according to weekly hematological profile); (c) nafarelin (2 micrograms/kg s.c. daily for 48 and 52 wk); and (d) cyclophosphamide plus nafarelin [same schedule as above with cyclophosphamide (570 and 698 mg/kg total dose) starting 7 wk after beginning nafarelin]. Plasma testosterone, spermatogenesis, and ejaculate volume were completely suppressed by nafarelin prior to starting cyclophosphamide. By 2 wk after cessation of treatment (posttreatment, PT), plasma testosterone reached normal levels, and at 5 wk PT ejaculates appeared which reached normal volumes 2 to 3 wk later. Normally motile ejaculated spermatozoa were noted at 6 to 8 wk PT in nafarelin-only-treated animals; normal sperm numbers were reached at 14 wk PT. The animals receiving cyclophosphamide plus nafarelin were azoospermic for the entire 65-wk PT period, and at 65 wk PT no germinal cells were found upon evaluation of testicular histology. Sperm numbers in cyclophosphamide-only-treated animals began to rise 10-11 wk PT and reached 150 x 10(6) sperm/ejaculate at approximately 65 wk PT (contemporaneous control dogs had sperm numbers of approximately 300-600 x 10(6)/ejaculate). Spermatogenesis in these cyclophosphamide-only-treated animals was normal in most seminiferous tubules at this time. The addition of nafarelin to cyclophosphamide treatment thus exacerbated the deleterious effects of cyclophosphamide on the testes, suggesting caution for use of such a protocol clinically.

Animals↗
PubMed1987

Abnormal auditory brain-stem responses in hallucinating schizophrenic patients.

Abnormal auditory brain-stem responses (ABRs) were recorded in 10 out of 20 schizophrenic in-patients. The response abnormalities did not show any correlation to the degree of psychopathology, sub-group of schizophrenia, age, sex, or cerebral ventricular enlargement. Nor was there any correlation to previous neuroleptic treatment: a pathological ABR was recorded in 5 of the 8 patients who had never received such medication. A statistically significant relationship was found between ABR pathology and auditory hallucinations: 9 of the 11 patients who admitted having hallucinations exhibited brain-stem response abnormality, whereas ABR abnormality was recorded in only 1 of the 9 patients who denied having hallucinations. The data imply that brain-stem dysfunction is involved in the psychopathology of schizophrenia, and that interference with the auditory pathways in the brain-stem may induce auditory hallucinations in schizophrenic patients.

Adult↗
PubMed1986

Peripheral airways function and nonspecific airways reactivity in cigarette smokers.

Increasing concentrations of inhaled aerosolized histamine acid phosphate were administered to 31 heavy cigarette smokers from a smoking cessation clinic. Nineteen of 31 smokers (mean age +/- ISD: 39.6 +/- 11.5 yrs; pack years 25.5 +/- 13.5) failed to reduce forced expired volume in one second (FEV1) while inhaling histamine and were labelled nonresponders. In 12 of 31 smokers (age 38.4 +/- 9.4 yrs; pack years 23.0 +/- 10.5), extrapolated provocation concentration of inhaled histamine required to reduce forced expired volume in one second (FEV1) by 10 percent (PC10) could be determined and these smokers were labelled responders. We also measured maximum expiratory flow volume curves with air and also a mixture of 80 percent helium and 20 percent oxygen (HeO2) to determine the percentage of increase in maximal flow at 50 percent vital capacity breathing HeO2 as compared to air (delta Vmax50), and the slope of phase III of the single breath oxygen test (delta N2/L). In the responders, PC10 ranged from 1.4 mg/ml to 10.2 mg/ml (mean 5.5 +/- 3.3 mg/ml) and delta Vmax50 ranged from 7.1 percent to 68.4 percent (mean 39.6 +/- 18.3 percent). There was a significant positive correlation between PC10 and delta Vmax50 (r = 0.77, p less than 0.01), and a significant negative correlation between PC20 and delta N2/L (r = -.61, p less than 0.01). There was no difference between responders and nonresponders in mean values for lung function tests, allergy skin tests, or symptoms. These results suggest that there may be two fundamentally different groups of smokers with peripheral airways dysfunction: one group in which dysfunction is associated with, or related to, airways reactivity, and one group in which dysfunction is related to other factors.

Adult↗
PubMed1983

Assessment of a new spermicidal agent against ejaculated dog and human spermatozoa in vitro.

The spermatostatic potencies of a new vaginal contraceptive agent, RS-37367, and a standard surfactant compound, nonoxynol-9, have been compared by using ejaculated dog and human spermatozoa. RS-37367 was 25 to 50 times more potent than nonoxynol-9 against dog spermatozoa. Nonparallel concentration-response lines were obtained against human spermatozoa. Concentrations of RS-37367 causing immediate spermatostasis against dog spermatozoa resulted in vesiculation of the plasma and outer acrosomal membranes of spermatozoa; similarly, immediately spermatostatic concentrations of nonoxynol-9 were associated with the previously documented generalized membrane stripping. The activities of both RS-37367 and nonoxynol-9 were affected by the concentration of dog spermatozoa in semen-compound mixtures. Short-term (5-minute) exposure of spermatozoa to concentrations of RS-37367 not immediately spermatostatic resulted in progressive immobilization of spermatozoa. Extensive washing of the spermatozoa was not able to reverse this effect, in contrast to spermatozoa transiently exposed to nonoxynol-9.

Animals↗
PubMed1980

Follow-up study with computerized tomography and clinical evaluation 5 to 10 years after surgery for pituitary adenoma.

This study was based on 24 consecutive patients operated on for pituitary adenoma with suprasellar extension, and treated postoperatively with radiotherapy. The follow-up period was 5 to 10 years. A clinical examination, endocrine evaluation, perimetry, computerized tomography (CT) and sellar roentgenography were performed in 19 of 20 surviving patients. The CT scans revealed four recurrences, while perimetry only showed an increased visual field defect in one patient. Plain sellar films were of no value for diagnosis of recurrence. Prolactin determinations seemed to have a limited value in recurrence diagnosis, but very high levels spoke in favor of a recurrence. Thus, CT was found to be the superior method of diagnosing recurrences. It is proposed that CT be used regularly in the follow-up study of patients operated on for a pituitary adenoma.

Adenoma↗
PubMedDate not supplied

Inability of continuous long-term administration of D-Nal(2)6-LHRH to abolish fertility in male rats.

A highly potent agonist of LHRH, [6-D-(2-naphthyl)-alanine]-LHRH, was administered chronically for 12 weeks to adult male rats by repetitive implantation of pellets, and its effects upon mating, fertility, and reproductive organ weights have been evaluated. Although significant declines in testicular (P less than 0.001) and epididymidal (P less than 0.001) weights were achieved, no effects on seminal vesicles, prostate, or pituitary weights were observed. After 12 weeks of continuous treatment, three of six agonist-treated rats were still successfully impregnating females. The decline in successful impregnation appeared to be related to the observed reduction in testicular spermatogenesis and in numbers of epididymal spermatozoa. The drug effects appeared reversible, as all six of the agonist-treated rats were fertile by the fifth week after cessation of treatment. Plasma levels of testosterone were markedly elevated immediately after implantation of each pellet and consistently, but not significantly, lowered during the inter-implantation periods. These observations, and the lack of effect on accessory organ weights, are consistent with the maintenance of libido in these treated rats. This is the second demonstration of a selective inhibition of spermatogenesis in the absence of a marked decline in gonadal steroidogenesis with this agent. As in the first demonstration using twice weekly injections, the degree of inhibition of spermatogenesis was insufficient to abolish fertility in the treated male rats.

Animals↗