Search PubMed⌕ Search

Biomedical subjects

G Berg

Publications and source records attributed to G Berg.

At least 163 records · Page 9Linked to original sources
PubMed1989

Potentiation of the poliocidal effectiveness of free chlorine by a buffer.

Poliovirus 1 was inactivated by free chlorine at pH 9.0 three times more rapidly in boric acid (0.05 M)-NaOH buffer than in purified (carbon-filtered, deionized) water. Thus, at a given concentration of free chlorine, it took three times longer to inactivate the same fraction of the poliovirus in purified water than in the boric acid-NaOH buffer. Conversely, in a given period of time, three times more chlorine was required to inactivate a given percentage of the virus in purified water than in the boric acid-NaOH buffer. Buffers are almost always used to control pH in disinfection studies with free chlorine and with other chlorine compounds also. The use of buffers for pH control in such disinfection studies may distort the resulting data and, at least for waters that contain little salt, may cause serious overestimation of the rates at which viruses are inactivated.

Boric Acids↗
PubMed1989

Potentiation of the virucidal effectiveness of free chlorine by substances in drinking water.

At 5 degrees C, poliovirus 1 was inactivated by free chlorine (FC) at pH 9.0 more than 10 times as rapidly in drinking water as in purified water. Because ions that comprise many salts potentiate the virucidal effectiveness of FC, we believe that ions and possible other substances in the drinking water potentiated the virucidal effectiveness of FC. Since viruses may be much more sensitive to chlorination in drinking waters than laboratory tests in purified waters have heretofore led us to believe, it may be possible to reduce the amounts of FC applied to many water supplies for disinfection and thereby perhaps reduce the quantities of halomethanes and other toxic compounds produced in these supplies by the chlorination process.

Antiviral Agents↗
PubMed1989

Reversal of brain metabolic abnormalities following treatment of AIDS dementia complex with 3'-azido-2',3'-dideoxythymidine (AZT, zidovudine): a PET-FDG study.

Brain glucose metabolism was evaluated in four patients with acquired immunodeficiency syndrome (AIDS) dementia complex using [18F]fluorodeoxyglucose (FDG) and positron emission tomography (PET) scans at the beginning of therapy with 3'-azido-2',3'-dideoxythymidine (AZT, zidovudine), and later in the course of therapy. In two patients, baseline, large focal cortical abnormalities of glucose utilization were reversed during the course of therapy. In the other two patients, the initial PET study did not reveal pronounced focal alterations, while the post-treatment scans showed markedly increased cortical glucose metabolism. The improved cortical glucose utilization was accompanied in all patients by immunologic and neurologic improvement. PET-FDG studies can detect cortical metabolic abnormalities associated with AIDS dementia complex, and may be used to monitor the metabolic improvement in response to AZT treatment.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Quantitative comparison of cerebral glucose metabolic rates from two positron emission tomographs.

The rapid progress in positron emission tomography technology has created the dilemma of how to compare data from old and new tomographs. We examined cerebral metabolic data from two scanners, with different spatial resolutions and methods of attenuation correction, to see if data from the lower resolution tomograph (ECAT II) could be "corrected" and then compared to data from the higher resolution scanner (Scanditronix PC1024-7B). Nine subjects were scanned on both tomographs after a single injection of [18F]2-fluoro-2-deoxy-D-glucose. Regional and lobar gray matter metabolic rates for glucose were obtained from comparable images from each scanner. Ratios of lobar to global gray matter metabolism also were calculated. Regression coefficients and percent differences were computed to compare ECAT II and PC1024 data. Twenty-four of the 36 regions showed significant regression slopes, and PC1024 measures of glucose utilization ranged from 30% to 120% higher than those from the ECAT II. Lobar differences between the two machines were less variable (50% to 80%), and ratios generally differed by only +/- 5%. Since there was no simple and consistent relation between regional metabolic rates on the two tomographs, an overall adjustment of regional ECAT values for comparison to PC1024 values would be impossible. A region-by-region adjustment would be necessary. On the other hand, ratios are sufficiently similar that direct comparisons could be made.

Aged↗
PubMed1988

Glucose uptake, lactate release, ketone body turnover, metabolic micromilieu, and pH distributions in human breast cancer xenografts in nude rats.

Glucose uptake, lactate release, ketone body utilization, spatial distribution of glucose, lactate, and ATP concentrations as well as tissue pH distributions were systematically investigated in s.c. and/or "tissue-isolated" human breast cancer xenografts in T-cell-deficient rnu/rnu rats. Large variations in all parameters were detected within and between tumors indicating a very nonuniform substrate turnover. Glucose was taken up by all xenografts. Glucose consumption rates increased with increasing glucose availabilities, implying that the glucose uptake is mainly determined by the efficiency of nutritive tumor blood flow. The average glucose uptake was 0.37 mumol/g/min in medullary and 0.26 mumol/g/min in squamous cell carcinomas of the breast. At wet weights below 5 g, medullary breast cancers consumed more glucose than squamous cell carcinomas (2P less than 0.05). Most tumors (97%) released lactate in an amount linearly related to glucose consumption. The lactate production of medullary (0.33 mumol/g/min) and squamous cell (0.31 mumol/g/min) breast cancers was similar. In general, the xenografts utilized ketone bodies. beta-Hydroxybutyrate was consumed by 82% and acetoacetate by 73% of the tumors, the uptake rates being linearly related to the respective availabilities. The mean uptake of beta-hydroxybutyrate was 3.48 nmol/g/min and that of acetoacetate 2.56 nmol/g/min. No significant differences were seen between medullary and squamous cell breast cancers. The beta-hydroxybutyrate/acetoacetate ratio in the tumor-venous blood rose with decreasing tumor blood flow indicating the development of hypoxia at advanced growth stages. Glucose, lactate, and ATP levels were all very heterogeneously distributed in medullary and squamous cell tumors as compared with normal tissue. No relationship was evident between the spatial distribution of concentrations of these three substrates. The xenografts were acidotic compared with pH values in normal subcutis. The mean tissue pH in medullary breast cancers was 6.81 +/- 0.25 (SD). Compared with these values, the tissue pH distribution in squamous cell breast cancers was shifted to significantly higher values. The mean pH of the latter tumors was 7.04 +/- 0.19 (2P less than 0.001). From the experimental data presented there is clear indication that the metabolism of the xenografts investigated was mainly determined by the efficiency of nutritive blood flow, i.e., by substrate availability, and not by the metabolic demand of the cancer cells.

Animals↗
PubMed1988

Long-term administration of 3'-azido-2',3'-dideoxythymidine to patients with AIDS-related neurological disease.

3'-Azido-2',3'-dideoxythymidine (AZT) has been administered to 7 patients with human immunodeficiency virus-associated neurological disease: 3 with dementia, 2 with peripheral neuropathy, 1 with dementia and peripheral neuropathy, and 1 with T-10 paraplegia. Six of the patients showed improvement in their neurological dysfunction on being administered AZT, as assessed by clinical evaluation, neuropsychological testing, nerve conduction studies, and/or positron emission tomographic scans. Three of these 6 patients showed sustained improvement 5 to 18 months after the initiation of AZT therapy. These results suggest that certain human immunodeficiency virus-associated neurological abnormalities are at least partially reversible following the administration of antiretroviral therapy and provide a rationale for further studies using antiretroviral chemotherapy.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Climacteric symptoms among women aged 60-62 in Linköping, Sweden, in 1986.

By means of a simple postal questionnaire, all women aged 60, 61 and 62 (n = 2015) living in the community of Linköping, Sweden, were screened for vasomotor symptoms and local vaginal complaints. After one reminder, answers were received from 73% of the women. At the time of the survey (April 1986) all the women were post-menopausal, the median period since menopause being 11 yr. Slightly over one in four of the women (27%) were suffering from sweating and hot flushes. Ten percent (10%) of the women who were more than 15 yr post-menopausal still had moderate to severe climacteric symptoms. Vasomotor symptoms were significantly more common among oophorectomized women than among those whose ovaries were intact. Local vaginal symptoms were positively correlated with urinary problems, repeated urinary tract infections and a high risk of disturbance of sexual activity. It was concluded that climacteric symptoms often persist for more than 15 yr after the menopause.

Climacteric↗
PubMed1988

Longitudinal study of the early neuropsychological and cerebral metabolic changes in dementia of the Alzheimer type.

To examine the progression of neuropsychologic and metabolic changes in the early stages of dementia of the Alzheimer type (DAT), we studied 11 midly demented patients longitudinally. Three aspects of neuropsychological function were measured: memory, attention to complex sets and abstract reasoning, and lateralized functions, i.e., language and visuoconstruction. Regional cerebral metabolic rates for glucose were measured in frontal, parietal, and temporal association cortices. Our results show that, in general, memory deficits are the first neuropsychological impairments to occur in DAT, followed by problems with attention to complex cognitive sets and abstract reasoning, which are followed in turn by deficits in language and visuospatial abilities. In addition, neocortical metabolic abnormalities usually precede impairment of neocortically mediated attention and abstract reasoning by 8 to 16 months, and precede impairment of neocortically mediated language and visuospatial function by 12 to 37 months. These findings suggest that the first nonmnestic neuropsychological consequence of neocortical physiological dysfunction in DAT is a loss of attentional capacity. Since neocortical metabolic changes generally precede the appearance of neocortically mediated neuropsychological dysfunction, physiologic dysfunction may exist for some time before cognition is affected.

Aged↗
PubMed1988

Group therapy with schizophrenic patients in outpatient departments.

Twelve schizophrenic patients were treated with neuroleptic drugs and psychoanalytically oriented group therapy during a period of 2 years. Twelve other patients, matched with regard to the state of their disease, sex, age, civil status and social situation, were given neuroleptic drugs and contact therapy during the same period. All patients were evaluated by the same test procedures. The Rorschach test, the Defence Mechanism Test (DMT), interviews and a self-evaluation test, were performed before and after 2 years of treatment. The dates of discharge, number of days in hospital and neuroleptic drugs prescribed were recorded for all patients over a 2-year period before, during and after treatment. Half of the patients improved, regardless of the treatment they received. No evaluation instrument used before the start of treatment could predict the patients who later improved. After 2 years of treatment, it was assessed that the patients who improved required a further period of insight therapy.

Adult↗
PubMed1988

Variable bioavailability of papaverine.

The plasma concentration curves of papaverine have been studied in nine healthy males and seven patients after administration of single intravenous (80 mg) and oral (80 mg) doses. The bioavailability of the drug was highly variable with a mean of 28% (range 5-99%) but reproducible within the same individual (4 of the volunteers) after a repeated (80 mg) oral dose. The calculated half-life after intravenous administration ranged between 1.2-6.6 hours (mean 3.0). The mean apparent volume of distribution was 3.1 l/kg and the mean total plasma clearance was 836 ml/min. It is concluded that papaverine shows an unacceptable inter-individual variation in the bioavailability after oral administration of 80 mg tablets.

Administration, Oral↗
PubMed1988

Low-temperature stability of viruses in sludges.

Enteroviruses survived for up to 38 days without diminishing in numbers in extended-aeration sludges maintained at 5 degrees C. In oxidation ditch sludges similarly maintained, enteroviruses survived for up to 17 days without diminishing in numbers. The pHs of the sludges in this study were well inside the pH 6 to 8 corridor in which destruction of enteroviruses by the detergents and ammonia present in sludges reportedly does not occur. Unexplained, however, was the survival of large numbers of enteroviruses in sludges at pH 3.5, a pH at which some anionic detergents commonly present in sewage are rapidly virucidal. The long survival of enteroviruses in these sludges at 5 degrees C indicates that such sludges can probably be stored under refrigeration in the laboratory for extended periods while awaiting processing without suffering significant losses in enterovirus numbers.

Cold Temperature↗
PubMed1988

Optimum pH levels for eluting enteroviruses from sludge solids with beef extract.

This study demonstrates that elution of enteroviruses from a mixture of primary- and activated-sludge solids with beef extract at pH 9.2 +/- 0.2 may be less efficient than elution with beef extract at pH 7.2 +/- 0.2 and that elution of enteroviruses from extended-aeration-sludge solids with beef extract is at best no more efficient at pH 9.2 +/- 0.2 than at pH 7.2 +/- 0.2. Thus, the common practice of adjusting the pH of beef extract used for eluting enteroviruses from the natural neutral level of the elutant to alkaline levels is unnecessary and probably undesirable.

Animals↗
PubMed1988

Low back pain during pregnancy.

All pregnant women from a well defined area (the central district of the County of Ostergötland, Sweden) attending antenatal clinics over a period of seven months were interviewed with regard to low back pain during pregnancy. Of 862 women who answered the questionnaires, about half developed some degree of low back pain. Seventy-nine women who were unable to continue their work because of severe low back pain were referred to an orthopedic surgeon for an orthoneurologic examination. The most common reason for severe low back pain was dysfunction of the sacroiliac joints. Physically strenuous work and previous low back pain were factors associated with an increased risk of developing low back pain and sacroiliac dysfunction during pregnancy.

Back Pain↗
PubMed1987

Response of human-immunodeficiency-virus-associated neurological disease to 3'-azido-3'-deoxythymidine.

Four patients with human-immuno-deficiency-virus-associated neurological disease were treated with 3'-azido-3'-deoxythymidine (AZT). Three (two with chronic dementia, and one with chronic dementia and peripheral neuropathy) improved as assessed by clinical examination, psychometric tests, nerve conduction studies, and/or positron emission tomography; there was no improvement in the fourth patient who presented with paraplegia. These results support the hypothesis that certain AIDS-virus-associated neurological abnormalities are reversible by antiretroviral chemotherapy.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Effects of enprofylline, a new xanthine derivate, on human pregnant myometrium.

The recently developed xanthine derivate, enprofylline, was studied in an in vitro system with human pregnant myometrium, in particular its effect on spontaneous myometrial contraction, cyclic adenosine monophosphate content, cyclic adenosine monophosphate protein kinase, and cyclic adenosine monophosphate-and cyclic guanosine monophosphate-dependent phosphodiesterase activity. Enprofylline was shown to be a rather potent smooth muscle relaxant [inhibitory concentration that decreases response by 50% (IC50) = 3 X 10(-5) mol/L] and an almost equally potent cyclic adenosine monophosphate-dependent phosphodiesterase inhibitor (IC50 = 10(-4) mol/L), whereas it was a less potent cyclic guanosine monophosphate-dependent phosphodiesterase inhibitor. Enzyme kinetic studies revealed that enprofylline is a competitive cyclic adenosine monophosphate phosphodiesterase inhibitor. Enprofylline increased the cyclic adenosine monophosphate content in a dose-dependent way with subsequent increased activity of cyclic adenosine monophosphate-dependent protein kinase. It is suggested that enprofylline relaxes myometrial smooth muscles and that this is at least partly the result of interference with the cyclic adenosine monophosphate system.

3',5'-Cyclic-AMP Phosphodiesterases↗