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Biomedical subjects

J A Christensen

Publications and source records attributed to J A Christensen.

At least 19 recordsLinked to original sources
PubMed1992

[Rapidly progressing glomerulonephritis].

20 patients with rapidly progressive glomerulonephritis were treated at the nephrological section, Medical Department A, Haukeland Hospital from 1973 to 1988. Nine patients had an idiopathic type of nephritis, while seven patients had this type of glomerulonephritis secondary to systemic lupus erythematosus, endocapillary glomerulonephritis, Henoch-Schönleins purpura or Wegener's granulomatosis. Four patients had antibodies to glomerular basement membrane. All renal biopsies showed extracapillary proliferation and tubular cell damage. All patients were given immunosuppressive treatment with corticosteroids and cytotoxic drugs. Nine patients who were admitted to the hospital from 1973 to 1978 were not treated with plasmapheresis, 11 patients from 1978-1988 were all treated with plasmapheresis. After one year of observation, six of the nine patients in the first group had died, while this applied to only two in the group treated with plasmapheresis. Early diagnosis and plasma exchange, in addition to immunosuppression, seems to be the best treatment for these patients.

Adrenal Cortex Hormones↗
PubMed1989

[Clinical significance of early kidney biopsy].

We use the unexpected results of five kidney biopsies to discuss how early biopsy in renal disease can change the therapy and correct the diagnosis of the disease. The first patient was a 73 year-old male diabetic who had osteomyelitis and developed rapidly progressive glomerulonephritis. The next patient was a 72 year-old man who was treated for cardiac failure and increasing serum creatinine. The kidney biopsy revealed rapidly progressive glomerulonephritis. The third patient developed acute renal failure after an episode with vomiting. Here the histological diagnosis was acute renal failure and parenchymatous renal disease could be ruled out. The next patient was a 13 year-old girl. She had proteinuria (5-6 g/d) and hypertension (200/140 mm Hg). After four months, serum creatinine was 200 mumol/l. She was then biopsied, and we found membranoproliferative glomerulonephritis type 1. After the diagnosis was established she was treated with immunosuppression and her condition improved. The last patient was a 55 year-old male diabetic. He developed nephrotic syndrome and the histological diagnosis of the kidney biopsy was membranous glomerulonephritis stage 1. Six months after the kidney biopsy we found carcinoma of the lung. This underlines the importance of the fact that 10% of membranous glomerulonephritides are tumour associated.

Adolescent↗
PubMed1989

[Membranoproliferative glomerulonephritis].

During the period 1981-1986, membranoproliferative glomerulonephritis was demonstrated in ten patients admitted to the Medical Department, Haukeland Hospital. At the time of the diagnosis all patients had proteinuria and hematuria, and six of them had renal failure. Seven patients exhibited nephrotic syndrome and three patients developed progressive renal failure during the observation period. Three patients died during the follow-up period. Four patients were treated with Cyclosporine A and corticosteroids. With this therapy the proteinuria disappeared in two of the patients with nephrotic syndrome. Immunosuppressive treatment may be tried if the disease shows signs of progression. We believe that some of these patients may benefit from cyclosporine A.

Cyclosporins↗
PubMed1989

Granular epithelioid cells of the kidneys in salmon adapted to fresh- and seawater.

The occurrence of granular epithelioid cells in the kidney arterial vessels was studied in one- and two-year-old Atlantic salmon during the physiological fresh- and seawater periods. The purpose of this study was to make long-term comparison on the morphology of the renin angiotensin system in the same fish species. One-year-old salmon living in freshwater had a statistically significant higher number of granular epithelioid cells (39.9 +/- 8.3/mm arterial vessel) than the two-year-old fish living in seawater (29.8 +/- 5.2/mm arterial vessel, P less than 0.00001). There was also a significant difference from month to month between the groups (P less than 0.05), but not within the groups (P greater than 0.07 freshwater, P less than 0.3 seawater). With the electron microscope the granules were found evenly distributed within the cytoplasm. They were of high electron density and lined by a single membrane. The granules were composed of a finely granular material. The recorded data on length and weight showed that all fish ate and developed normally. From our results and the available literature, we conclude that in primitive vertebrates, the renin angiotensin system is primarily involved in renal circulation, with vasoconstriction on the afferent side of the glomerulus.

Animals↗
PubMed1989

Renin-positive granulated Goormaghtigh cells. Immunohistochemical and electron-microscopic studies on biopsies from patients with pseudo-Bartter syndrome.

It is difficult to distinguish between Goormaghtigh cells (G-cells) and media cells of the glomerular arterioles at the border of the Goormaghtigh cell field. Consequently, it has been unclear whether renin-positive G-cells are normally present and also whether renin-producing cells are recruited from the pool of renin-negative G-cells upon stimulation of the renin-angiotensin system (RAS). In the present study, immunohistochemical and electron-microscopic experiments have been carried out on serially sectioned kidney biopsies from four patients with pseudo-Bartter syndrome. The results strongly suggest that with long-lasting stimulation of the RAS all renin-negative ("secretory resting") G-cells are ultimately converted into renin-producing granular cells.

Adult↗
PubMed1988

Peripolar cells in the avian kidney.

Four white leghorn chickens were injected with furosemide (20 mg per kg body weight) three times at 12 h intervals and the kidneys fixed by perfusion after 36 h. Five chickens were injected with DOCA (desoxycortone trimethylacetate, 75 mg per kg body weight) three times at 12 day intervals and the kidneys fixed by perfusion after 36 days. Serial sections from the kidneys of these two groups of birds were made and the number of peripolar cells recorded. These recordings were compared with the number of peripolar cells in four normal, untreated chickens. A significant increase in the number of peripolar cells was recorded in the furosemide treated group. No significant change was seen in the DOCA treated group. However, in the DOCA-group heavily granulated podocytes were found. No distinct morphological difference was found between the granules in the podocytes and the granules in the peripolar cells. A possible lysosomal nature of the peripolar cell granules is discussed.

Animals↗
PubMed1988

Hyperperfusion injury of the human kidney in different glomerular diseases.

Investigations of biopsy material from human kidneys with different forms of glomerulonephritis (n = 1,240) and with diabetic glomerulosclerosis (n = 406) performed in order to find changes caused by hyperperfusion of the kidney tissue gave the following results: (1) Hyperperfusion injury occurs in the different forms of glomerulonephritis with varying frequency. It was rarely found in immunologically negative mesangioproliferative glomerulonephritis. The highest incidence was found in patients with membranoproliferative glomerulonephritis type I. (2) Hyperperfusion injury was also found in kidneys with diabetic glomerulosclerosis. The frequency of this finding increased with the degree of the diabetic changes. (3) The hyperperfusion injury was seen as a complication of glomerulonephritis or diabetic glomerulosclerosis only when the patient clinically had developed malignant hypertension and when the serum creatinine level was elevated, a sign of compensated retention. (4) In patients with glomerulonephritis, the hyperperfusion changes occurred more frequently in males than in females. Diabetic glomerulosclerosis was complicated by hyperperfusion injury with the same frequency in both sexes. (5) Patients with hyperperfusion changes of the kidneys always excrete large amounts of protein in the urine. (6) Hyperperfusion changes occur first in the juxtamedullary glomeruli. The intermediate glomeruli are affected later and the subcapsular glomeruli last.

Adolescent↗
PubMed1988

Role of hyperperfusion in different glomerular diseases.

In various forms of glomerulonephritis, diabetic glomerulosclerosis and decompensated benign nephrosclerosis hyperperfusion injury of the glomeruli may be found in addition to the basic disease in patients with malignant hypertension. The changes consist of adhesions, subendothelial capillary hyalinosis and fat droplets in the hyalin material and in endothelial cells. They occur far more often in males than in females. The highest frequency of hyperperfusion injury was found in patients with membranoproliferative glomerulonephritis type I. The lowest frequency was found with membranous glomerulonephritis. The juxtamedullary part of the kidney, which is not autoregulated, is earlier and more severely affected than the subcapsular part. Hyperperfusion changes occur in the middle and eventually in the subcapsular part of the cortex only when the glomeruli in the juxtamedullar cortex are sclerotic.

Diabetic Nephropathies↗
PubMed1987

Nuclear and cell area measurements in the cytological evaluation of pleural effusions: a study of subjective assessments and morphometric measurements.

Morphometric measurements of cellular area, nuclear area and nuclear:cytoplasmatic ratio were performed on single cells in pleural effusions from 15 patients with effusion caused by bronchial, ovarian, or mammary carcinoma. The results were compared with corresponding measurements on mesothelial cells in pleural effusions from 15 patients without malignant disease. Significant differences were found between the mean values from cellular area, nuclear area, and nuclear:cytoplasmatic ratios in mesothelial cells from benign effusion versus malignant cells from effusions associated with metastatic growth. Such morphometric measurements are, however, of little value in routine diagnostic work as more than 90% of the cells in the two groups showed similar values.

Cell Nucleus↗
PubMed1987

The granular epithelioid cells in the kidney of the lemon sole (Pleuronectes microcephalus Donovani).

Serial sections from kidneys of 5 aglomerular lemon soles (Pleuronectes microcephalus) demonstrated the presence of anastomosing arteriolar networks in the caudal half of the organs. There was no preferred location of the networks, which were found both near the surface and in the deeper parts of the kidney. The size of the networks varied; the largest measured more than 900 micrometers in the longest axis and covered an area larger than 500,000 micrometers2, whereas the smallest measured about 60 micrometers in diameter with an area of 2040 micrometers2. The larger networks were invariably located close to large intrarenal veins. Anastomoses were found between the arteriolar networks and the peritubular capillaries and also associated with veins. The walls of the arterioles were composed of granulated epithelioid cells, exhibiting numerous intracytoplasmic granules. These granules occasionally had a rod-like appearance with a paracrystalline substructure. Using antibodies directed against murine and human renin, the epithelioid cells in the walls of the arteriolar networks and the cytoplasmic granules revealed a positive immunoreaction. The results suggest that the renin-angiotensin system in the aglomerular lemon sole may be important for both the regulation of the systemic blood pressure and the blood supply to the peritubular capillaries of the kidney.

Animals↗
PubMed1987

Effect of volume depletion on the afferent arterioles in the avian kidney.

Nine white leghorn chickens were injected i.m. with furosemide (10 to 60 mg/kg body weight) twice daily for 18 days. The birds were then anesthetized with a combination of equithesin and diazepam and the kidneys perfused via the heart. Kidney tissue was sectioned serially and the granular epithelioid cells were counted in the juxtaglomerular apparatuses of the furosemide treated birds and in 3 normal chickens. Hyperplasia and hypergranulation of the epithelioid cells was found to occur in the juxtaglomerular apparatuses of both mammalian and reptilian type nephrons (with and without Henles loop) in the furosemide treated group. This finding was interpreted as an effect of hypovolaemia on the juxtaglomerular apparatuses. Furosemide caused an immediate stop in weight gain, an increase in the erythrocyte volume fraction and a sudden drop in blood pressure. The blood pressure later rose to subnormal levels. The heart rate was not altered. Plasma sodium and chloride fell significantly one day after furosemide administration and remained low throughout the experiment. Potassium fell during the second part of the experimental period. Captopril was injected after 18 days of furosemide treatment and lowered the blood pressure significantly. This was interpreted as indirect evidence for the presence of renin in the granular epithelioid cells and indicates the importance of the renin angiotensin system in maintaining the blood pressure in hypovolaemic conditions.

Animals↗
PubMed1985

Structure of the avian kidney.

The kidneys from 6 domestic fowl were fixed in situ by perfusion from the left ventricle. In the bird there are two types of nephrons. One reptilian-type without Henle's loop and medullary tissue, and one mammalian-type with Henle's loop lying in medullary tissue. Serial sections from kidney tissue embedded in plexiglass or in paraffin were used to study the architecture of eight reconstructed reptilian-type nephrons from different cortical levels. All reconstructed nephrons had four major bends, but particularly in the subcapsular nephrons additional bends parallel to the kidney surface were found. There was no loop of Henle, but before entering the collecting duct the distal tubule usually had a very thin-walled segment. No proximal convoluted part was found in the reptilian-type nephrons. The length of the tubules varied between 3,000 microns and 6,000 microns. In the distal tubule a macula densa segment was found in all nephrons of the reptilian and mammalian type. The capillary network between the inter- and intralobular veins was composed of increasingly larger capillaries towards the intralobular vein. Segments of the distal tubule were indented into these capillaries and completely surrounded by them. In the nephrons of the mammalian type the proximal tubule was found to be convoluted as is usual for mammalian species.

Animals↗
PubMed1982

Granular epithelioid cells in the kidney of the Atlantic salmon (Salmo salar).

Two-year-old salmon at the migrating stage were kept in two different aquaria, the one containing seawater, the other freshwater. The fish kept in seawater showed retarded growth at the beginning of the year, but their growth had caught up with and passed the freshwater fish by the end of the year. At this time, 69 out of 79 of the freshwater fish died without any evident reason. When the fish were in seawater or freshwater at the biologically appropriate time, the number of granular epithelioid cells was equal in both groups. But the fish forced to remain in freshwater subsequently developed a considerably higher number of epithelioid cells. This may reflect an effort to maintain normal blood pressure.

Animals↗
PubMed1982

Juxtaglomerular apparatus in the domestic fowl (Gallus domesticus).

The juxtaglomerular apparatus in the kidney of the domestic fowl was studied with the light and electron microscope after fixation by vascular perfusion. The height of the macula densa cells was greater and the internuclear distance less than were those of other distal tubule cells. Goormaghtigh (lacis) cells were found in the angle between the hilar arterioles and the glomerulus. The branching pattern of the basement membrane of the macula densa was extensive, surrounding both the Goormaghtigh cells and the mesangial cells. The basement membrane ended in the walls of both hilar arterioles and in the glomerular capillaries. Thus, all juxtaglomerular and glomerular structures were linked together by the branches of basement membrane. The afferent and efferent arterioles were often found ramifying in the mesangial cell mass. Granular epithelioid cells and adrenergic nerves were found within the glomerulus.

Animals↗
PubMed1980

Delayed neurologic injury secondary to high-voltage current, with recovery.

A patient with delayed neurologic injury secondary to high-tension current, with recovery, is presented. The mechanism of injury and pathophysiology are felt to be either vascular or direct damage to the spinal cord. This case demonstrates the need for frequent, repeated neurologic examinations of electrical injury victims. The cause of delay in onset of neurologic injury and the mechanism of recovery need further experimental study.

Adult↗
PubMed1979

Pharmacokinetics of femoxetine in man.

The pharmacokinetics of a structurally new 5HT-uptake inhibitor, femoxetine (FG 4963), with antidepressant properties have been investigated in man using a radioactive as well as a non-labelled substance. A two compartment open model gives a good description of the data, both after oral and intravenous administration. The substance was almost completely absorbed after an oral dose, but only 5-10% reached the systemic circulation due to extensive first pass metabolism. The metabolites had distribution and excretion rates similar to the parent compound. Only a small part (less than 2%) was excreted as femoxetine in the urine. The urinary excretion of the parent compound varied more than a 100-fold depending on the pH of the urine. The urine pH, however, did not influence the plasma concentration of femoxetine. Most of the substance (up to 80%) was eliminated by urinary excretion of metabolites, and only a small part of the radioactive dose was excreted in the faeces (up to 11%). The pharmacokinetic parameters were not found to be dose dependent in the range investigated, but it was not possible to decide whether the bioavailability was dependent on the dose. The variation between subjects was rather large, giving only a limited possibility for prediction of the plasma concentration from one subject to another.

Administration, Oral↗