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Biomedical subjects

P Holck

Publications and source records attributed to P Holck.

35 records · Page 2Linked to original sources
PubMed1993

Structure and segmental localization of glycogen in the diabetic rat kidney.

Pathological accumulations of glycogen were studied in the kidney tubular epithelium in untreated STZ-induced diabetic rats of 50 days diabetes duration. Blood glucose concentrations were approximately 17 mM, and the animals had no ketonuria. At the termination of the experiment, the kidneys were perfusion-fixed, and serial sections were cut from the renal capsule to the tip of the papilla and stained with toluidine blue and periodic acid Schiff. By tracing tubular profiles from section to section in a light microscope, the outlines of nephrons were reconstructed, and abnormal glycogen accumulations were mapped in accordance with the outlines. The exact segmental localization, character, and extension of the glycogen accumulations were determined. The predominant location of the pathological glycogen accumulations was in the thick ascending limb of Henle's loop. Dot-shaped and diffuse-appearing glycogen accumulations were discretely distributed throughout the segment, and large confluent cytoplasmic accumulations of glycogen were also present. On a continuous basis, glycogen was present only in the cortical thick ascending limb of Henle's loop and the macula densa segment excluding the macula densa cells. In the distal convoluted tubule and the cortical collecting duct system, scattered dot-shaped and diffuse glycogen accumulations were discretely distributed. Furthermore, glycogen appeared as confluent, cytoplasmic accumulations in the initial part of the descending thin limb of Henle's loop. In addition, glycogen accumulations were found in nuclei within a narrow stripe of the outer stripe of the outer medulla in the medullary thick ascending limb of Henle's loop.

Animals↗
PubMed1991

Fixation of the macula densa with fixatives of different osmolarities in normal and diabetic rats.

The influence of different fixative osmolarities on the ultrastructure of the macula densa region has been studied in normal and in streptozotocin diabetic rats after 50 days' duration of diabetes. In vivo perfusion fixation of the kidneys was performed retrogradely through the aorta in five groups of controls and diabetic animals with a 1% glutaraldehyde fixative in a Tyrode solution. Between groups, the osmolarity of the fixative solution varied from 216 to 476 mosm/l. This was accomplished by variation of the NaCl concentration of the fixative vehicle. The tissue was embedded in Epon and midcortical tissue was prepared for electron microscopy. The volume density of the lateral intercellular spaces between the macula densa cells was measured applying a morphometric technique. The results confirmed that the lateral intercellular spaces are narrowed in diabetes and also showed that for all fixative osmolarities the difference is persistent between diabetic and non-diabetic animals, except at very low osmolarities. The abnormal macula densa ultrastructure has been suggested to be connected with the functional abnormalities in diabetes, i.e. the resetting of the tubuloglomerular feedback and subsequent increases in GFR. It is therefore of interest to further understand the mechanisms underlying the narrowing of the lateral intercellular spaces in diabetes. The present study has shown that the size difference in lateral intercellular spaces between diabetic and normal animals is reproducible over a wide range of fixative osmolarities, further indicating that it is an in vivo phenomenon. The diminution of the LIS in diabetes could perhaps indicate a decrease in signal function, previously reported at the MD level in diabetic animals, contributing to the increased GFR in diabetes.

Animals↗
PubMed1991

Macula densa morphology in diabetic rats with and without hyperglycemia and in nondiabetic hyperglycemic rats.

The morphology of the macula densa was studied in streptozotocin diabetic insulin-treated rats with hyperglycemia for 50 days, and in three groups of diabetic rats that were first hyperglycemic for 50 days and then put onto different insulin regimes to achieve normoglycemia. One of the latter groups of rats was given a single dose of insulin and was studied 4 hours later when the animals were normoglycemic. The other two groups were treated with insulin for 5 and 15 days in such a way that the animals were nearly normoglycemic throughout the treatment period. In a further set of experiments two groups of nondiabetic rats were made hyperglycemic by intravenous injection of glucose and studied after 1 and 10 minutes of hyperglycemia. A perfusion fixation of the kidneys was performed in all animals with a 1% glutaraldehyde solution retrograde through the aorta, and the tissue was embedded in Epon for light and electron microscopy. Juxtaglomerular apparatuses were randomly selected from thick sections and reembedded for electron microscopy. The volume density of the lateral intercellular spaces (LIS) between the macula densa cells was determined on electron micrographs, by use of a morphometric technique. The study showed that the volume density of the LIS comprised about 10% in the nondiabetic normoglycemic animals and about 1.5% in the diabetic hyperglycemic animals. In all the insulin-treated normoglycemic diabetic animals, the volume density of the LIS was the same as in the nondiabetic normoglycemic animals (about 10%), independent of the duration of the insulin treatment. In the nondiabetic hyperglycemic animals the volume density of the LIS comprised about 1.5%, as in the diabetic hyperglycemic animals. In conclusion, the volume density of the LIS between the macula densa cells is reduced in a hyperglycemic state, irrespective of how the hyperglycemia was achieved, and they are normalized (i.e., enlarged) in insulin-treated diabetic normoglycemic animals irrespective of the duration of the treatment. The results indicate that changes in the blood glucose concentration have a major impact on the size of the macula densa LIS.

Animals↗
PubMed1990

[From the history of brain research].

This paper describes the understanding of the brain and central nerve system from antiquity up to our own century. It also describes the first attempts at brain research in the Nordic countries, and in Norway in particular.

Animals↗
PubMed1989

[Asbestos in the work environment. The occurrence of pulmonary changes among workers exposed to asbestos at an electrotechnical factory].

A number of workers exposed to asbestos dust for more than three months were medically examined for lung diseases caused by asbestos. A follow-up examination four years later revealed that the lung capacity of these workers was significantly lower than in the normal population. 9% of them showed changes in the lungs caused by asbestos dust, but no case of cancer was discovered. There was no development of significance in these changes during the four years.

Adult↗
PubMed1988

Ultrastructure of the macula densa in streptozotocin diabetic rats.

Morphometric analyses of the macula densa in streptozotocin diabetic rats have revealed, that the volume density of the large lateral intercellular spaces, which are present in normal animals between the macula densa cells, decreases significantly in magnitude from 8.7 to 1.5% in diabetic animals. The volume density of cytoplasmic glycogen in the macula densa cells increases significantly from 5.4% in the controls to 14.8% in the diabetic animals, but the total volume density of mitochondria is the same in the two groups. The contact area between macula densa cells and the Goorgmaghtigh cells is increased by 38% in the diabetic animals compared with controls. The structural abnormalities in the macula densa in response to diabetes might be considered a structural counterpart to the alterations in the tubuloglomerular feedback mechanism and the increase in glomerular filtration rate in diabetes.

Animals↗
PubMedDate not supplied

Pap prevalence and cervical cancer prevention among Alaska Native women.

The goals of the Alaska Native Women's Health Project (WHP) were to determine the following: (1) Pap prevalence based on chart review before and during an intervention period; (2) the level of understanding of cancer and cancer screening services with emphasis on cervical cancer; (3) use and satisfaction with current health maintenance services; and (4) improvement in knowledge and cancer screening rates following intervention. A random sample of 481 Alaska Native (Eskimo, Aleut, Indian) women living in Anchorage were interviewed face to face about their understanding of cancer risk factors (tobacco use, sexually transmitted diseases (STDs), reproductive issues), cancer screening examinations (Pap test, breast self-examination (BSE), breast exam by a provider, mammography), and their attitudes about health care and health care services. Sixty-two percent of control women were documented to have had at least one Pap test within the 3-year period prior to the beginning of the study; however, only 9% were documented to have had annual Pap screening. The intervention included distribution of educational materials, counseling on any woman's health issue, special evening clinics, and reminders (mail/phone call) of scheduled Pap appointments.

Adult↗
PubMedDate not supplied

Cancer mortality among Alaska natives, 1994-1998.

Although overall cancer mortality rates in the U.S. declined throughout the 1990s, Alaska Native rates increased. This study compares mortality patterns of Alaska Natives for the period, 1994-1998, and U.S. Whites, and examines changes in rates since 1960-1969. We used death certificate data and Indian Health Service population estimates to create age-adjusted mortality rates for Alaska Natives. We compared these rates to NCHS mortality for U.S. Whites. In all, 597 Alaska Natives died of cancer over the five-year period, 1994-1998, their age-adjusted average annual mortality rate (224.5 per 100,000) was thirty percent higher than that of U.S. Whites (166.7 per 100,000), a statistically significant excess (OR = 1.3, 95% CI: 1.2-1.4). Alaska Natives were forty percent more likely to die of lung cancer than U.S. Whites (OR = 1.4, 95% CI: 1.2-1.6). This population also demonstrated elevated mortality rates for several other smoking-related cancers. Also, Alaska Natives are at excess risk for nearly all cancers of the digestive system. Alaska Natives experienced the same or lower mortality rates for genitourinary cancers excluding cancer of the kidney. Smoking related cancers, and particularly, lung cancer, were the major contributors to the excess mortality rates. These data suggest that the burden of cancer on the Alaska Native healthcare system will continue to increase as the population ages. Intensified efforts to modify behavioral risk factors are needed.

Alaska↗
PubMedDate not supplied

Cancer incidence in Alaska Natives thirty-year report 1969-1998.

The Alaska Native Tumor Registry includes data from 1969 to the present. This report provides incidence rates over the thirty year period, 1969 through 1998, and compares trends over time for Alaska Natives (AN) with those of US Whites and Blacks. To examine current rates, average annual age-adjusted incidence rates for AN for 1984-98 are compared with US Whites. Data from the registry document numerous differences in rates of occurrence of specific cancers compared to US Whites and Blacks. Studies of these differences may provide clues to the causes and risk factors for the cancers. Most importantly, these data show that although cancer was considered a rare disease in the Alaska Native population as recently as the mid-twentieth century, the incidence rate for all cancers combined among Alaska Natives is now as high as that of US Whites, and even higher in women. On the other hand, despite relative differences in rates, the most frequently diagnosed cancers among Alaska Natives are the same as US Whites. Cancers of the lung, colon/rectum, breast, and prostate are most frequently diagnosed among Alaska Natives and in the U.S. These four cancers comprise over 50% of all diagnosed invasive cancers. Cancer of the lung is almost entirely preventable by eradication of tobacco use. Screening and early detection have been proven to reduce mortality for cancers of the colon/rectum and breast. Primary and secondary prevention of these cancers could markedly improve morbidity and mortality.

Black or African American↗
PubMedDate not supplied

NIHSS applied to cerebral neurological dive injuries as a tool for dive injury severity stratification.

BACKGROUND: Evaluation via National Institutes of Health Stroke Scale (NIHSS) upon presentation in hospital triage following ischemic stroke is predictive of recovery or progression to neurological deficits. Cerebral injuries sustained while diving have symptoms similar to stroke. Applying the NIHSS to dive injuries may successfully summarize neurological dive injuries, providing a standardized tool for study of dive injury data. METHODS: We retrospectively determined NIHSS scores for a diverse population of 192 divers presenting to the University of Hawaii recompression chamber from 1983-2002, both prior to initial treatment and after all treatment. Spinal and vestibular decompression sickness cases were excluded. RESULTS: The performance of the NIHSS among this diving population was similar to its performance as an accepted tool in evaluation of ischemic stroke, although results are influenced by the abundance of mild injury cases in the data set. The estimated C-statistic with NIHSS predicting no observable deficit was 0.88, and predicting post NIHSS of 0-1 was 0.85 (vs. 0.86 when applied to stroke). Sensitivity for predicting recovery (NIHSS 0-1) at discharge was 0.99 (vs. 0.97 for stroke). CONCLUSIONS: The NIHSS applied to cerebral dive injuries has adequate predictive ability and correlates with other measures of dive injuries, while providing a standardized, more graduated scale. The NIHSS may be useful as a standardized measurement for evaluation of treatment regimens and adjunctive therapy for diving injuries.

Adolescent↗