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Biomedical subjects

J Christensen

Publications and source records attributed to J Christensen.

At least 217 records · Page 12Linked to original sources
PubMed1983

Inherited ophthalmoplegia with intestinal pseudo-obstruction.

A new inherited neuromuscular disease was identified in 4 patients (1 male, 3 females), offspring of consanguineous marriages, belonging to the same kindred. The proband was a 24-year-old female with history of ptosis and ophthalmoplegia since childhood and progressive intestinal pseudo-obstruction for the last 4 years of her life. A sural nerve biopsy showed axonal and demyelinating neuropathy. Muscle biopsies of pectoral and gastrocnemius revealed myopathic alterations with marked variation in muscle fiber size, atrophy of both fiber types and normal mitochondria. An upper gastrointestinal study showed barium in the stomach after 8 h and jejunal diverticula. Tests for absorption of fat, protein, carbohydrate, folic acid and vitamin B12 were normal. Serum levels of vitamin A and lipoproteins were also normal. The patient underwent partial gastrectomy and gastrojejunostomy. Postoperatively, she developed severe pancreatitis, sepsis, peritonitis and expired. Tissue samples from the proband and from her brother, revealed normal mucosa, but degeneration of smooth muscle of the stomach and small intestine. The myenteric plexus and vagus nerves were normal. The biochemical studies of contractile proteins (myosin, actin, tropomyosin) in the fresh and cultured smooth muscle cells of the proband obtained at the time of gastrectomy showed a 50-75% decrease in the synthesis of different contractile proteins. Turnover of contractile proteins and synthesis and turnover of collagen showed normal values. The reduction in synthesis of contractile proteins may account for the weak peristalsis and be a factor in the pathogenesis of the intestinal pseudo-obstruction.

Adult↗
PubMed1983

Brain scintigraphy with Tc99-pertechnetate in the evaluation of patients with cerebrovascular lesions. The diagnostic value related to age of the lesion and to the size, type and localisation revealed by CT-scan.

Brain scintigraphy with Tc99-pertechnetate (Tc99-scan) was performed 4 times in 95 consecutive stroke patients: on average 5 days, 18 days, 103 days and 194 days after the stroke. The type (infarct, hematoma), size and localisation of the lesion was evaluated by CT-scan performed 3 times in all: on average 3 days, 18 days and 207 days after the stroke. The detection rate of Tc99-scan was 31% on day 5, 47% on day 18, 18% on day 103 and 9% on day 194. The detection rate was however highly dependent upon: (i) the localisation of the lesion, i.e. superficially localised lesions were nearly always identified (90%) while infarcts localised deep in the hemisphere were identified in only 20% of the patients; (ii) the size of the lesion, i.e. large deep infarcts were seen with a much higher frequency than small deep infarcts. The detection rate of the CT-scan was practically not dependent upon the time of investigation: 63% on day 3, 70% on day 18, 69% on day 207. The detection rate of the Tc99-scan and CT-scan was nearly identical for large superficially localised lesions 2-3 weeks after the stroke. In this period, however, CT-scan identified 30 deep infarcts. Only 12 of these were identified by Tc99-scan.

Brain↗
PubMed1983

Characterization of a T-antigen-negative revertant isolated from a mouse cell line which undergoes rearrangement of integrated simian virus 40 DNA.

A transformation revertant has been isolated from an unusual line of simian virus 40 (SV40)-transformed BALB/c-3T3 cells in which rearrangements of integrated viral sequences are common. The revertant produces no SV40 T antigens, yields no virus on fusion with permissive cells, and can be retransformed by SV40 virions. SV40 DNA sequences are present within the cellular DNA, but interruption of the viral early transcription region by deletion and recombination with cellular sequences precludes the synthesis of T antigens. Analysis of this revertant lends further support to the notion that large T antigen plays an essential role in the maintenance of transformation in SV40-transformed BALB/c-3T3 cells. Examination of integration of SV40 DNA in this revertant, as well as in a temperature-sensitive A transformant, after retransformation by SV40 confirms that sequence homology plays little role in the insertion of SV40 DNA into cellular chromosomes.

Animals↗
PubMed1983

A familial visceral myopathy with external ophthalmoplegia and autosomal recessive transmission.

A new visceral myopathy family was identified. The disease in this family is transmitted by an autosomal recessive gene. Only 3 patients were identified from approximately 1500 family members. All 3 patients are the products of intermarriage. The patients had gastric atony, dilatation of the entire small bowel, and multiple diverticula throughout. Pathology of the jejunum showed fibrosis and degeneration, mainly of the longitudinal muscle layer, indistinguishable from that of previously reported families. Two of the patients also had ptosis and external ophthalmoplegia. Jejunal manometric studies were performed on the proband's asymptomatic mother and five siblings. All had normal esophageal manometric studies and upper gastrointestinal x-rays. The mother and three siblings had abnormal jejunal manometric studies characterized by the absence of phase 1 in some of the migrating motor complexes and increased motility indices in phase 2. We conclude that familial visceral myopathy can be transmitted by an autosomal recessive gene, and that jejunal manometry is a sensitive technique to identify asymptomatic heterozygotes.

Adult↗
PubMed1983

Differences between esophageal body and lower esophageal sphincter in mitochondria of smooth muscle in opossum.

In opossum, contractions of smooth muscle of the circular layer of the esophageal body resist oxygen deprivation, while tone of the lower esophageal sphincter requires oxygen. Thus, morphologic differences in mitochondria could distinguish the two types of muscle. Transverse strips, cut at regular intervals along the smooth-muscle segment of the esophageal body, were physiologically identified as muscle of body or sphincter. Transverse sections of the circular muscle layer were examined by transmission electron microscopy. Muscle cell profiles located between the ends of the nucleus and the tips of the cells were used to evaluate the number of mitochondrial profiles per muscle cell profile, mitochondrial mass (relative total area of mitochondrial profiles in each muscle cell profile), mitochondrial position (distance from the center of each mitochondrial profile to the nearest point on the cell membrane relative to mean radius of that muscle cell profile), and mass of smooth endoplasmic reticulum (relative total area of profiles in each muscle cell profile). In the nonnucleated part of the muscle cells, sphincter muscle had a greater ratio of mitochondrial profile area to cell profile area (p less than 0.05), mitochondrial profiles in sphincter muscle were more central in location than in esophageal body muscle (p less than 0.05), and sphincter muscle contained more endoplasmic reticulum than body muscle (p less than 0.05). Sphincter muscle did not differ from body muscle in mean muscle cell profile area and number of mitochondrial profiles per muscle cell profile in this region of the muscle cell (p greater than 0.05).

Animals↗
PubMed1983

Arrangement of the myenteric plexus throughout the gastrointestinal tract of the opossum.

Silver impregnation of the myenteric plexus of the opossum gut was used to find differences among various regions. In the esophagus, the plexus was sparse and ganglia were spaced irregularly, many being parafascicular. Ganglia were sparse in the striated-muscle region, but more frequent in the smooth-muscle region. In the stomach, uniformly spaced ganglia were large and intrafascicular; ganglia were larger in the distal stomach than in the proximal stomach. The proximal stomach contained thick fascicles, called shunt fascicles, radiating from the lesser to the greater curvatures and bypassing ganglia. A thick nerve bundle encircled the pylorus. In the small intestine, the regularly spaced ganglia were large and intrafascicular. In the cecum, they were small and intrafascicular. In the colon, they were large and intrafascicular. Shunt fascicles, like those of the proximal stomach, extended from the rectum into the distal colon. In the rectum, the plexus was sparse, and ganglia were small and distributed irregularly. Many ganglia were parafascicular. Unique knots of tangled fascicles were frequent in the rectum; these were called labyrinthine nodes. The least densely innervated regions of the gut are the lower esophageal sphincter and the rectum. Major differences in the anatomy of the plexus characterize the different regions of the gut.

Animals↗
PubMed1982

Fractures of the shaft of the tibia treated with AO-compression osteosynthesis.

Ninety-six displaced fractures of the shaft of the tibia in a series of 162 consecutive fractures were treated by AO internal fixation. Forty per cent were open fractures, of which 93 per cent received prophylactic treatment with antibiotics at the time of admission. The average time between the accident and the operation was 10 hours in closed fractures and 5 hours in open fractures. All cases were operated on by senior surgeons. The infection rate was 5.3 per cent in closed fractures, and 0 in open fractures. The average stay in hospital was 13 days. More than 90 per cent returned to work within 6 months after the accident. No case of pseudarthrosis or re-fracture was seen. The median time to final review was 36 months. Rigid internal fixation is advocated for all displaced fractures of the shaft of the tibia and is advocated as an urgent procedure especially in open fractures, and should be performed by experienced surgeons only. Rigid internal fixation appears to provide effective prophylaxis against secondary soft-tissue damage and limits the consequences of the initial soft-tissue damage.

Adult↗
PubMed1982

Determinants of pulmonary interstitial fluid accumulation after trauma.

We have sequentially measured the daily extravascular lung water (EVLW) changes in 16 severely traumatized patients to better define the principal etiologic factors causing post-traumatic interstitial fluid accumulation and subsequent respiratory failure. We found that severe hemorrhagic shock (mean initial BP = 40 mm Hg), massive transfusion (12.7 liters of blood), and crystalloid resuscitation with resulting hemodilution of plasma colloid osmotic pressure (PCOP) (PCOP less than or equal to 15 mmHg) do not cause EVLW accumulation. Post-traumatic elevations in EVLW were seen after lung contusion (average EVLW = 15.3 +/- 2.5 ml/kg), sepsis (average EVLW = 17.1 +/- 2.9 ml/kg) and cardiac failure (EVLW = 15.3 +/- 0.3 ml/kg). Severe hemorrhagic shock, massive transfusion, and crystalloid resuscitation with resulting hemodilution of plasma colloid oncotic pressure do not cause EVLW accumulation. Post-traumatic elevations in EVLW are seen after lung contusion, sepsis, and cardiac failure. We conclude that after trauma elevations in capillary hydrostatic pressure and capillary permeability alterations resulting from lung contusion or sepsis are the primary determinants of interstitial fluid accumulation.

Adult↗
PubMed1982

Modeling the effect of wall movement on absorption in the intestine.

Intestinal wall movements may influence intestinal absorption by inducing flow in the luminal volume. Direct evidence for this is scant and weak. Such evidence was sought by mechanical and analytical modeling. Wall motions resembling peristaltic ring contractions were induced in dialysis tubing filled with a concentrated salt solution and immersed in tap water. The disappearance of solute from the inside of the tube was monitored with conductivity probes and correlated with various kinds of wall motions. In analytical modeling, equations representing wall motions, flow, and mass transfer were constructed, with the assumptions that ring contractions are axisymmetric, the wall is totally compliant, the Reynolds' number is low, the fluid volume is conserved, the no-slip condition exists at the luminal surface, and inertial flow is negligible. In the mechanical model, wall motions caused a 30-35% increase in absorption that was matched in the corresponding analytical model. The analytical model demonstrated that the effect is progressively greater for nonpropagative stationary contractions, asymmetric progressive contractions, and symmetric progressive contractions, the increase being 33, 70, and 100%, respectively.

Animals↗
PubMed1982

Juxtaglomerular apparatus of the human kidney: correlation between structure and function.

Electron microscopic and morphometric evaluation of the juxtaglomerular apparatus (JGA) of the human kidney showed the following: (1) The JGA of the human kidney consists of the epithelioid cells of afferent and efferent arterioles, the Goormaghtigh cells, and the macula densa, and it is abundantly supplied with sympathetic nerves. (2) The macula densa is in contact with the juxtaglomerular cell complex (JGC), the endocrine part of the JGA, via the Goormaghtigh cell field. The surface area of the macula densa is much larger than is the contact area with the JGA, totalling, in the healthy human kidney, some 66 cm2. (3) The total volume of all JGC's is 26 to 40 mm3. (4) Morphometric investigations of the JGC showed that appropriate stimulation by a decrease in the intrarenal or systemic blood pressure led to hypertrophy and hyperplasia of the JGC, which, in extreme cases, may also lead to a transformation of both the Goormaghtigh cells and mesangium cells into epithelioid cells.

Humans↗
PubMed1982

Anatomy of the myenteric plexus of the opossum esophagus.

Silver-impregnated stretch preparations of the opossum esophageal body and lower esophageal sphincter were compared as to the general aspect of the plexus, density of perikarya and ganglia, type and size of ganglia, nerve bundle diameter, density of nerve bundle intersections, and relations between ganglia and nerve bundle intersections. Density of perikarya and ganglia, but not density of nerve bundle intersections, declined along the esophagus, with a nadir at the sphincter. The proximal body contained 960-1358 perikarya/cm2 and the sphincter, 70-333 perikarya/cm2. Ganglia contained 3-100 cells, 54% having less than 10. Many small ganglia lay outside nerve bundles (parafascicular ganglia), the proportion being greatest in the sphincter (25%-54%). Many ganglia (15%-22%) were remote from nerve bundle intersections and many intersections were remote from ganglia, 28%-35% in the body and 66%-69% in the sphincter. Nerve bundle diameter was a single population with a skewed distribution; the mode was about 0.1 mm.

Animals↗
PubMed1981

Malignant fibrous histiocytoma of the lung.

A case of malignant fibrous histiocytoma of the lung is reported. The tumour margin was well circumscribed, showing an expanding border and no capsule. The main part of the tumour was composed of spindle-shaped fibroblast-like cells arranged in broad fascicles with a partially storiform pattern. Other parts of the tumour were arranged in a haphazard pattern, containing many mononucleated and multinucleated giant cells. Ultrastructurally six different cell types were encountered. The dominant type was a fibroblast-like cell; also present were many giant cells and some histiocyte-like cells, together with their intermediate forms, and few undifferentiated mesenchymal cells. We consider this tumour to have developed from the peribronchial connective tissue; it has the same cellular composition as the malignant counterpart arising in soft tissues.

Female↗
PubMed1981

Effects of autonomic drugs on cat colonic muscle.

The cat colon was divided in vitro into four equal segments, and one transverse and one longitudinal strip (1.5 cm x 2.5 mm) was taken from each. Transverse strips contracted rhythmically, each strip generating 0.9-1.2 g force. Longitudinal strips contracted irregularly, each strip generating 11.9-16.8 g force. Acetylcholine (10(-7) to 10(-5) M) and physostigmine (10(-8) to 10(-5) M) increased frequencies in longitudinal (P less than 0.05) but not in transverse strips (P greater than 0.05) and increased amplitudes in both (P less than 0.05). Atropine (10(-8) to 10(-6) M) reduced frequencies and amplitudes in longitudinal strips (P less than 0.05) but only amplitudes in transverse strips (P less than 0.05). Phenylephrine (10(-7) to 10(-5) M) and norepinephrine (10(-7) to 10(-5) M) increased amplitudes in transverse strips (P less than 0.05) but decreased frequencies and amplitudes in longitudinal strips (P less than 0.05). Isoproterenol (10(-7) to 10(-5) M) decreased frequencies an amplitudes in both transverse and longitudinal strips (P less than 0.05). Dopamine (10(-7) to 10(-5) M) decreased amplitudes in longitudinal strips (P less than 0.05). Tetrodotoxin (10(-7) M increased amplitudes in transverse (P less than 0.05) but not in longitudinal strips (P greater than 0.05). Both layers are affected by cholinergic and adrenergic drugs. Muscarinic receptors are excitatory in both. alpha-Adrenergic stimulations result in excitation in circular muscle and inhibition in longitudinal muscle. Circular muscle is dominated by an inhibitory neural tone.

Animals↗