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Biomedical subjects

S Carlson

Publications and source records attributed to S Carlson.

At least 127 records · Page 7Linked to original sources
PubMed1987

Alteration of intestinal tight junction structure and permeability by cytoskeletal contraction.

Permeabilized intestinal absorptive cell brush borders contain a perijunctional ring of actin and myosin (PAMR) that can be induced to contract. Recently, morphological changes suggestive of PAMR contraction were shown to occur in absorptive cells of ileal epithelium after exposure to cytochalasin D (CD) (J. Cell Biol. 102: 2125-2136, 1986). With this response, altered tight junction structure and enhanced tight junction permeability also occur. To further assess the relationship between PAMR contraction and enhanced tight junction permeability, we examined the effect of the uncoupler 2,4-dinitrophenol (DNP) on this CD response. Progressive depletion of functionally defined intraepithelial energy stores occurred with DNP concentrations of 0.1-1 mM. Such DNP concentrations did not independently impair tight junction barrier function. Depletion of energy stores before CD exposure ablated the ability of CD to induce abnormalities of tight junction permeability. Similarly, PAMR condensation and alterations in tight junction structure could be dissociated from CD exposure by prior depletion of functional energy reserves. These data tie CD elicited alterations in tight junction structure and permeability to an energy dependent event that appears to be PAMR contraction. We speculate that tensile forces within the PAMR regulate tight junction structure and function.

Actins↗
PubMed1986

Effects of cytochalasin D on occluding junctions of intestinal absorptive cells: further evidence that the cytoskeleton may influence paracellular permeability and junctional charge selectivity.

Intestinal absorptive cells may modulate both the structure and function of occluding junctions by a cytoskeleton dependent mechanism (Madara, J. L., 1983, J. Cell Biol., 97:125-136). To further examine the putative relationship between absorptive cell occluding junctions and the cytoskeleton, we assessed the effects of cytochalasin D (CD) on occluding junction function and structure in guinea pig ileum using ultrastructural and Ussing chamber techniques. Maximal decrements in transepithelial resistance and junctional charge selectivity were obtained with 10 micrograms/ml CD and the dose-response curves for these two functional parameters were highly similar. Analysis of simultaneous flux studies of sodium and the nonabsorbable extracellular tracer mannitol suggested that CD opened a transjunctional shunt and that this shunt could fully account for the increase in sodium permeability and thus the decrease in resistance. Structural studies including electron microscopy of detergent-extracted cytoskeletal preparations revealed that 10 micrograms/ml CD produced condensation of filamentous elements of the peri-junctional contractile ring and that this was associated with brush border contraction as assessed by scanning electron microscopy. Quantitative freeze-fracture studies revealed marked aberrations in absorptive cell occluding junction structure including diminished strand number, reduced strand-strand cross-linking, and failure of strands to impede the movement of intramembrane particles across them. In aggregate these studies show that CD-induced perturbation of the absorptive cell cytoskeleton results in production of a transepithelial shunt which is fully explained by a defect in the transjunctional pathway. Furthermore, substantial structural abnormalities in occluding junction structure accompany this response. Lastly, the abnormalities in occluding junction structure and function coincide with structural changes in and contraction of the peri-junctional actin-myosin ring. These data suggest that a functionally relevant association may exist between the cytoskeleton and the occluding junction of absorptive cells. We speculate that such an association may serve as a mechanism by which absorptive cells regulate paracellular transport.

Animals↗
PubMed1986

Persistent behavioural blindness after early visual deprivation and active visual rehabilitation: a case report.

Early long lasting binocular deprivation results in behavioural blindness in both man and experimental animals. However, few reported cases show that visual rehabilitation may improve visual behaviour. A 34-year-old man who had experienced 30 years of binocular deprivation due to bilateral cataracts received visual rehabilitation for one year. The rehabilitation included training in eye-hand co-ordination, recognition of objects, evaluation of distance and size, and mobility training. Despite signs of recovery of visual functions the patient never started to use vision in his normal life. The negative outcome of the rehabilitation is partly attributed to the patient's motivational problems and to the relatively short rehabilitation time. Visual rehabilitation may be successful when started immediately after the corrective operation on the eyes when the level of motivation is also high.

Adult↗
PubMed1983

Visual rehabilitation after long lasting early blindness.

A 23-year-old woman, blinded at an early age due to retinopathy of prematurity and cataract was successfully operated. After the operation the patient was behaviourally blind. Visual rehabilitation was started 9 months later and lasted 1 1/2 years. During this time the visual behaviour of the patient improved. Quantitative tests were designed to depict the progress. The functional improvement of the patient is in agreement with the findings of animal studies; binocular deprivation during the critical period of development causes behavioural blindness, which is partially recoverable. The result of this study indicates that the visual rehabilitation facilitates the process of recovery. The progress in visual behaviour is likely to reflect an improvement of the function of the associative systems of the brain.

Adult↗
PubMed1983

The effect of hypotensive anesthesia on cephalosporin concentrations in serum, soft tissue, and bone.

The objective of this study was to determine the efficacy of a hypotensive anesthetic in enhancing tissue perfusion while simultaneously controlling surgical blood loss. One hundred ten patients undergoing 126 total hip arthroplasties were administered either cephalothin or cefamandole on a double-blind basis. Hypotensive anesthesia was administered to 64 patients; 46 received a normotensive anesthetic. Degree of tissue perfusion was measured by the concentration of cephalosporin found in samplings of serum, soft tissue, and bone. These samples, obtained during the course of total joint arthroplasty, indicate that the hypotensive anesthetic sodium nitroprusside did not significantly alter the concentrations of cefamandole or cephalothin from those found in the normotensive group.

Anesthesia↗
PubMed1981

Early visual deprivation alters modality of neuronal responses in area 19 of monkey cortex.

Monkeys deprived on vision during the first year of life by lid suture appear functionally blind after the opening of the eyes, but move actively in familiar surroundings using somesthetic cues. Microelectrode recordings of multiple unit activity in the associative visual cortical area 19 of deprived monkeys indicated that 20% of the neuron groups studies responded only during active somatic exploration. In normal animals all neuron groups studied responses exclusively to visual stimuli, but in the deprived animals only 40% of them did. Visual deprivation alters the synaptic pathways to visual associative cortex enhancing the efficiency of those inputs that can mediate somatic information to this region.

Animals↗
PubMed1981

Diet modifications and behavioral changes for bariatric gastric surgery.

Gastric bypass and gastroplasty are effective in causing a reduction in weight averaging 55 percent of excess weight, 30 percent of initial weight, or 40 kg. in morbidly obese patients. Education in appropriate eating habits helps patients to lose weight and results in fewer complications. Patient education should emphasize behavioral changes, which include eating slowly and chewing well to prevent blockage, vomiting, and disruption of the staples and sutures. High-calorie beverages and frequent snacking should be avoided. Three meals per day eaten slowly and in a pleasant atmosphere will satisfy hunger. Gastric bariatric surgery makes the morbidly obese responsive to instruction. Dietitians have an important part to play in this rapidly expanding and effective treatment of a group of patients who until now have been ignored and rejected.

Behavior Therapy↗
PubMed1978

Touch.

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Humans↗
PubMed1978

Modification of visual functions of the parietal lobe at early age in the monkey.

In addition to the visual pathway ending in the visual cortex, visual information is also processed in the associative areas of the cortex. We have studied the posterior parietal association area (Brodmann's area 7), and in our sample about 40% of the neurons were influenced by visual stimulation or ocular movements. The visually activated neurons in this region in normal adult monkeys have large, binocular receptive fields and they respond well to all moving visual stimuli near the animal. They do not differentiate between different patterns of visual stimuli but respond well to objects of interest, such as food, drinks, new objects, etc. Many visual neurons also respond to somatic stimulation. Preliminary experiments on two young monkeys suggest that the visual input into area 7 is strongly modified by early visual deprivation. In one monkey monocular deprivation lead to total absence of any influence from the deprived eye to area 7. No deprivation effect was observed in the lateral geniculate nucleus of the thalamus and the effect in area 7 was stronger than in the visual cortex (area 17). One monkey raised with bilateral eye closure was behaviourally blind after the opening of the eyes and remained so for the observation period of one month. In area 7 of this monkey the proportion of recording sites responsive to visual stimulation was sharply reduced. In kittens binocular deprivation is known to effect the function of the visual cortex much less than monocular deprivation. It seems possible that at early age inputs representing different sensory systems compete for influence in the associative cortical areas in the same way as there is competition between inputs from the two eyes to the visual cortex.

Age Factors↗
PubMed1976

Evolution of an active psychogeriatric day hospital.

A geriatric day hospital was established as part of the psychogeriatric unit of the Royal Ottawa Hospital. While initially this day hospital was integrated with day hospital programs of other units, it became apparent that a separate facility was desirable. The activities and programs of the psychogeriatric day hospital, run by one registered nurse, were integrated with those of the geriatric inpatient unit. It was found to be advantageous for inpatients and day hospital patients to share the same physical facilities. The majority of day hospital patients came from the inpatient unit; almost all had affective disorders. The emphasis was on reintegration into the community. During the 1st year of operation there were 75 patients in the program; only 3 needed admission to the inpatient unit and 1 was readmitted after discharge.

Aged↗
PubMed1976

Primary care.

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Nursing Service, Hospital↗
PubMed1976

[Studies on virus inactivation by chlorine during water disinfection (author's transl)].

The studies described indicate a potential for water-borne transmission of viral diseases and the problems involved in virus inactivation by means of water chlorination. In contrast to the amount of free chlorine, the value of the oxidation-reduction potential (ORP) was found to be a criterion of virus inactivation. For virus inactivation, higher ORP values and longer periods of contact than for the killing of bacteria, respectively, were found to be necessary. To ensure the inactivation of poliovirus in water contaminated with organic substances, an ORP of + 780 mV (0.3-0.6 mg/l free chlorine) should be maintained for 15-30 min. Adenovirus has shown an almost identical resistance to inactivation. Possibilities for utilizing the mechanism of virus inactivation by the action of chemical disinfectants are discussed.

Chlorine↗