Low levels and partial exposure to palmitic acid improves mitochondrial function and the oxidative status of cultured cardiomyoblasts

Lipid overload or metabolic stress has gained popularity in research that explores pathological mechanisms that may drive enhanced oxidative myocardial damage. Here, H9c2 cardiomyoblasts were exposed to various doses of palmitic acid (0.06 to 1 mM) for either 4 or 24 h to study its potential physiological response to cardiac cells. Briefly, assays performed included metabolic activity, cholesterol content, mitochondrial respiration, and prominent markers of oxidative stress, as well as determining changes in mitochondrial potential, mitochondrial production of reactive oxygen species, and intracellular antioxidant levels like glutathione, glutathione peroxidase and superoxide dismutase. Cellular damage was probed using fluorescent stains, annexin V and propidium iodide. Our results indicated that prolonged exposure (24-hours) to palmitic acid doses ≥ 0.5 mM significantly impaired mitochondrial oxidative status, leading to enhanced mitochondrial membrane potential and increased mitochondrial ROS production. While palmitic acid dose of 1 mM appeared to induce prominent cardiomyoblasts damage, likely because of its capacity to increase cholesterol content/ lipid peroxidation and severely suppressing intracellular antioxidants. Interestingly, short-term (4-hours) exposure to palmitic acid, especially for lower doses (≤ 0.25 mM), could improve metabolic activity, mitochondrial function and protect against oxidative stress induced myocardial damage. Potentially suggesting that, depending on the dose consumed or duration of exposure, consumption of saturated fatty acids such as palmitic acid can differently affect the myocardium. However, these results are still preliminary, and in vivo research is required to understand the significance of maintaining intracellular antioxidants to protect against oxidative stress induced by lipid overload.

Isoorientin ameliorates lipid accumulation by regulating fat browning in palmitate-exposed 3T3-L1 adipocytes

Stimulation of fat browning using natural bioactive products is regarded as one of the promising approaches to treat obesity and insulin resistance. Here, we investigated the physiological effects of isoorientin on glucose uptake and lipid accumulation in insulin resistant 3T3-L1 adipocytes. To achieve this, 3T3-L1 adipocytes were exposed to 0.75 mM palmitate for 24 h, to induce insulin resistance, before treatment with 10 μM isoorientin or the comparative controls such as CL-316,243 (10 μM), pioglitazone (10 μM) and compound C (1 μM) for 4 h. Relevant bioassays and Western blot analysis were conducted on these insulin resistant cells. Our results showed that palmitate exposure could induce insulin resistance and mitochondrial dysfunction as measured by reduction in glucose uptake and impaired mitochondrial bioenergetics parameters. However, treatment with isoorientin reversed these effects by improving glucose uptake, blocking lipid accumulation, and modulating the process of mitochondrial respiration. Mechanistically, isoorientin could mediate lipid metabolism by activating 5' AMP-activated protein kinase (AMPK), while also effectively modulating the expression of genes involved in fat browning such as peroxisome proliferator-activated receptor gamma (PPAR)γ/α and uncoupling protein 1 (UCP1). In conclusion, isoorientin impacts insulin resistance in vitro by improving glucose uptake and mitochondrial function, consistent to modulating the expression of genes involved in energy metabolism and fat browning.

Islet cell response in the neonatal rat after exposure to a high-fat diet during pregnancy

Although pancreatic beta-cells are capable of adapting their mass in response to insulin requirements, evidence has shown that a dietary insult could compromise this ability. Fetal malnutrition has been linked to low birth weight and the development of type 2 diabetes later in life, while reduced beta-cell mass has been reported in adult rats fed a high-fat diet (HFD). Reported here are the effects of exposure to a HFD, during different periods of gestation, on neonatal rat weight and beta- and alpha-cell development. The experimental groups were composed of neonatal offspring obtained from Wistar rats fed a high-fat (40% as energy) diet for either the first (HF1), second (HF2), or third (HF3) week, or all three (HF1-3) weeks of gestation. Neonatal weights and circulating glucose and insulin concentrations were measured on postnatal day 1, after which the pancreata were excised and processed for histological immunocytochemical examination and image analysis. HF1 and HF2 neonates were hypoglycemic, whereas HF1-3 neonates were hyperglycemic. Low birth weights were observed only in HF1 neonates. No significant differences were detected in the circulating insulin concentrations in the neonates, although beta-cell volume and numbers were reduced in HF1-3 neonates. beta-cell numbers also declined in HF1 and HF3 neonates. alpha-cell volume, number and size were, however, increased in HF1-3 neonates. alpha-cell size was also increased in HF1 and HF3 neonates. In neonates, exposure to a maternal HFD throughout gestation was found to have the most adverse effect on beta-cell development and resulted in hyperglycemia.

An immunocytochemical profile of the endocrine pancreas using an occlusive duct ligation model

CONTEXT

Ligation of the pancreatic duct, distally to its confluence into the bile duct has been shown to induce endocrine tissue regeneration. The surplus endocrine tissue formed is presumed to be able to replace pathologically and/or experimentally compromised tissue.

OBJECTIVE

This is a quantitative study on the histology of duct ligated pancreas employing immunocytochemistry and computerised morphometry.

INTERVENTIONS

Pancreatic duct ligation was performed on 25 groups of six normal Sprague-Dawley rats. Experimental animals were sacrificed at 12-hour intervals from day one to ten post-duct ligation and every 24 hours thereafter to day 14, the pancreas removed, fixed and processed. Six consecutive 3-6 micron serial sections were cut on a rotary hand microtome, floated onto 3-aminopropyl-trimethoxysilan coated slides and alternatively immunocytochemically stained for insulin, glucagon, pancreatic polypeptide and somatostatin.

RESULTS

Pancreas transformation between days 1/2 and 3 1/2 was characterised by acinar deletion and the appearance of immunoreactive cells for the primary endocrine hormones. Transdifferentiation of existing endocrine tissue saw islet insulin core cells replaced by pancreatic polypeptide- and somatostatin positive cells, glucagon deletion and random appearance of all endocrine cell types within the inter-islet interstitium by day 3 1/2. Days 4 to 14 were characterised by cellular migration and islet reconstruction.

CONCLUSIONS

To date our laboratory has investigated transplantation of foetal tissue beneath the renal capsule in syngeneic, isogeneic and allogeneic normal and diabetic rats. As pancreatic duct ligation induces the development of surplus endocrine tissue our next step would be to investigate the use of ligated pancreas as a replacement for foetal tissue.

An ultrastructural study of the development of the chicken perineurial sheath

Three phases of perineurial development were recognised in the chicken sciatic nerve: (1) an early primitive phase during which the embryonic perineurium appeared to organise from the surrounding mesenchyme; (2) an intermediate phase of differentiation with the formation of a multilayered cellular network around the Schwann cell-axon complexes, and (3) a final phase of maturation during which the perineurial sheath showed features correlating with those of a functional barrier. Our observations support a mesenchymal origin for the perineurium rather than a schwannian derivation with clear separation of these 2 cell populations during all stages of development. Although the embryonic perineurial cells initially showed a fibroblast-like appearance, distinctive features of perineurial differentiation were present as early as 5 1/2 days (d) (Hamburger & Hamilton stage 28 embryo). Perineurial differentiation appeared to be intimately associated with developmental events in the Schwann cell-axon complexes, particularly during the period of most active Schwann cell proliferation. It is proposed that factors released by the Schwann cell-axon complexes during this period may be responsible for perineurial differentiation and organisation from the surrounding mesenchyme. The presence of endoneurial blood vessels following the appearance of perineurial basal lamina at 17 d (stage 43) suggested the emergence of a perineurial barrier. A perineurial architecture and cytological fine structure comparable to that of the adult animal was, however, only observed in the 10 d-old-chick.

Rural anaesthetic practices in the western Cape

The findings of specialist anaesthetists on visits to rural towns in the western Cape over 6 years are reported. The importance of academic units communicating with general practitioners, nursing staff and hospital authorities in their own working environment is emphasised. Hospital anaesthetic facilities and general practice anaesthetic methods are discussed and recommendations made and, in addition, common problems that could improve anaesthesia in general practice are summarised.

Accuracy or inaccuracy of spleen mass measurements from radionuclide images

In a retrospective study, scintigraphic spleen size was compared with actual spleen weight. Using the formula W = pi/7 h (h2 + 3ab), the normal weight was calculated too large and splenic enlargement was calculated too small. Other scintigraphic parameters seem to be just as unreliable. We suggest to judge scintigraphic spleen mass as normal and only be enlarged in obvious situations.

In-111 leukocyte scanning and partial functional asplenia in a patient with Sézary syndrome

Functional asplenia is described in the case report of an 80-year-old woman who was admitted with Sézary syndrome. The spleen could not be visualized by a Tc-99m tin colloid (SnC) liver and spleen scan, but was visualized by a Tc-99m sulfur colloid (SC) scan, suggesting a different mechanism in accumulation of SnC and SC in the spleen. In-111 oxine labeled Sézary cells could be found in the spleen, bone marrow, and lymph nodes.

Radiology and the law in South Africa

In terms of regulations gazetted in 1973, the Department of Health has control of the practice of medical radiology in South Africa. The regulations and the rules of the South African Medical and Dental Council that apply to radiology are discussed, and the legal position of workers is noted.

[Radiology in cases of trauma--an obligatory investigation]

The radiology of trauma is of increasing importance in South Africa, where the treatment of victims of motor accidents forms a major part of emergency medical practice. All practitioners should be aware of the medical and legal obligations that they have to fulfil in this investigation, which nowadays is regarded as part of clinical medicine. The most important principles in the radiology of trauma are briefly discussed.

[Clinical characteristics and genetic identity of the basal cell nevus syndrome (Gorlin-Goltz syndrome)]

The clinical, genetic, radiological, dental and dermatological aspects of 3 patients with the autosomal dominant basal cell naevus syndrome are reported. An analysis of the phenotypic features of 72 cases described in the literature is presented and compared with a previous analysis. Ash leaf hypopigmentation similar to that found in tuberous sclerosis represents a unique finding in this syndrome. Other similarities to the phacomatoses are discussed. We were able to support a previous report that patients with the basal cell naevus syndrome have a normal end-organ response to parathormone stimulation, and that it is most probably not related to pseudohypoparathyroidism, as earlier reports suggested.

[Radiological service at Tygerberg Hospital]

The Tygerberg Hospital, of the Medical Faculty of the University of Stellenbosch, has a decentralised radiological service where 50% of the radiology forms part of specialised departments. This obviates patient traffic and ensures an efficient technical service and close collaboration between the radiologist and the specialist concerned. The main department, when finally completed in a few years' time, will have 24 diagnostic rooms for general and special purposes and about 30 decentralised rooms.

The diagnosis of vitamin D deficiency rickets

A clinical, radiological and biochemical study of 300 Cape coloured out-patients in order to clarify the diagnosis of rickets and to establish its incidence in the specific ethnic group selected, is presented. 95 Cases (31.6%) were diagnosed as suffering from rickets. Analysis of the results indicates that radiological examination is necessary to confirm or exclude the clinical diagnosis. The most useful biochemical parameter is the serum level of alkaline phosphatase.

Effect of gamma radiation on the ripening of bartlett pears

Gamma radiation at doses of 300 Krad or more inhibits the ripening of Bartlett pears (Pyrus communis L.). Immediately after irradiation there is a transitory burst of C(2)H(4), which subsequently declines in fruits subjected to inhibitory doses. Ethylene production associated with ripening begins at the same time in unirradiated fruits and those subjected to noninhibitory doses, but the latter produces much more C(2)H(4) at the climacteric peak. Fruits subjected to inhibitory doses produce low levels of C(2)H(4) unless subjected to exogenously applied C(2)H(4), whereupon they produce enough of the gas to induce ripening in unirradiated fruits.Pears subjected to 300 and 400 Krad of gamma rays did not ripen even when held in a flowing atmosphere containing 1000 ppm of C(2)H(4) for 8 days at 20 degrees . It is concluded that the action of gamma rays on Bartlett pears involves both an inhibition of C(2)H(4) production and a decreased sensitivity of the fruit to the ripening action of the gas. Ripening of Bartlett pears is inhibited by gamma radiation only when applied to preclimacteric fruit.