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Biomedical subjects

S Carlson

Publications and source records attributed to S Carlson.

144 records · Page 8Linked to original sources
PubMed1975

[Water disinfection by means of chlorine: killing of aggregate bacteria (author's transl)].

Rising water demands ask for an increasing utilization of more or less contaminated surface water that has to be chlorinated prior to treatment. Especially during periods of lake bloom, the desired disinfecting effect is not achieved in spite of high concentrations of chlorine present. This is due to a coating of bacterial surfaces by substances such as algal products having a protective effect as demonstrated in experimental studies by the authors. Bacteria in a central position within bacterial aggregates as e. g. formed by the addition of flocculants in the process of water treatment, are also protected against the action of chlorine. In cases of inadequate filter backwashing, such aggregates may penetrate into clean water. Accumulations of bacteria in the shape of widespread growth may also form on activated carbon filters, ion exchangers, at walls of tanks under unfavourable hydraulic concitions, and in stagnant parts of supply pipes. Curves depiciting the kill of dyspectic E. coli differentiated by O-agglutination and S. anatum were exhibiting longer survival periods as compared with non-aggregate bacteria. For organisms differentiated by H-agglutination, kill was between these values. The killing rate was found to be a function of the oxidation-reduction poteential. Furthermore, survival times for E. coli and S. anatum were found to be different. It has been confirmed by these experiments that chlorine concentrations as common in the practice of water works frequently do not suffice to kill bacteria within aggregates and that a colony count does not permit conclusions as to the bacterial count if bacterial aggregates are present.

Agglutination↗
PubMedDate not supplied

Clinical decision-making and mammography referral.

BACKGROUND: Physician characteristics, practice/structural factors, and patient characteristics have all been found to influence mammography referral. The relationship of a patient's advanced age and comorbidity to the physician's decision has not received much attention. METHODS: Community-based, primary care physicians (n = 132) in two medium-sized U.S. cities completed questionnaires. RESULTS: Physicians report that they refer nearly all (89%) of the women ages 50-64 in their practice, slightly fewer of those 65-74 (83%), but many fewer (57%) of those 80 and over. Foreign medical graduates and physicians who are not board certified reported lower referral rates, and those who were residency trained reported substantially lower rates for the oldest patient group. Common reasons for not referring included assuming a gynecologist or another physician will make the referral, patient cost, comorbidity, and type of encounter, i.e., whether the patient is being seen for an acute condition. However, the lowest rate of referral was associated with believing that the patient was too old to benefit from early detection. CONCLUSIONS: Results are discussed in terms of the debate about whether guidelines should be based on patient age or functional status and the need to openly discuss and evaluate the decision rules being used.

Adult↗
PubMedDate not supplied

Albumin kinetics in hypoalbuminemic patients receiving total parenteral nutrition.

BACKGROUND: By using undenatured purified albumin preparations radiolabeled with iodine, the half-life of serum albumin in well patients who are stable is known to be approximately 17 days. However, when a patient is suffering with an acute illness such as sepsis, trauma, burns or after an extensive operative procedure, the serum albumin level decreases. It is not known whether this fall in serum albumin is due to increased catabolism, decreased synthesis, or a combination of both factors. This study explores the kinetics of albumin catabolism under these circumstances to clarify the issue. METHODS: 125I-labeled albumin was administered intravenously to 10 critically ill, hypoalbuminemic patients receiving total parenteral nutrition (TPN). Each subject had frequent blood samples taken for at least 10 days to measure the decline of plasma radioactivity over time. None was receiving unlabeled albumin during the investigation. It was assumed that the plasma decay would follow first-order kinetics after the early equilibration phase. Radioactivity of heparinized blood samples (counts/2 mL sample) were counted and the results were graphically expressed. RESULTS: One subject was not evaluated because he was discharged on the 8th day. The APACHE (acute physiology and chronic health evaluation) score for the other nine subjects ranged from 4 to 18 (mean, 7.5). The serum albumin remained below 3.0 g/dL in each subject and did not change statistically throughout the study. The radioiodinated albumin half-life ranged from 5.52 to 11.76 days (mean 9.10 days; compared with published normal of approximately 17 days). The equilibration time was 3 to 7 days. The average albumin catabolized for this group is similar to previously reported normal subjects, 0.18 g/kg/d. CONCLUSION: Hypoalbuminemic patients receiving TPN have markedly shortened plasma albumin half-lives, but the albumin catabolized per day is similar to normal patients. These data argue for both a synthetic and catabolic defect that explains the hypoalbuminemia in this patient group.

APACHE↗
PubMedDate not supplied

The development of sucking patterns and physiologic correlates in very-low-birth-weight infants.

The purpose of this investigation was to assess the development of nutritive sucking patterns and physiologic correlates in very-low-birth-weight infants. Fifty infants with a mean gestational age of 29.5 weeks (SD = 1.8 weeks) and mean birth weight of 1466 g (SD = 322 g) generated 106 sucking records. The mean number of sucks and maximum pressure increased with increasing postconceptual age. The time required per burst decreased between 32 weeks and 36 weeks. The mean time between sucks also decreased. The mean heart rates for the three 5-minute periods ranged from 158.56 to 177.97 bpm. Mean oxygen saturation ranged from 94.36% to 97.15%. Mean systolic pressure ranged from 69.82 mm Hg to 76.85 mm Hg mean diastolic pressure from 43.63 mm Hg to 45.33 mmHg. Sucking parameter measurements can be used to distinguish an infant who is maturing and organizing appropriately for postconceptual age.

Blood Pressure↗