The ultrastructural characteristics of the hair bulb of segmented heterochromia in the scalp hair

Segmented heterochromia is a pigmentary disorder characterized by alternating dark and light segments on each hair shaft. Our aim was to observe the ultrastructure of hair shafts and bulbs to understand the pathogenesis of the disease. Biopsy specimens including normal or diseased hair follicles were prepared for transmission electron microscopy. In dark segments, dense and ellipsoidal melanosomes were noted while small, round ones were found in the light segments. Two groups of melanosomes lined up on the matrix, one of which was composed of compact ellipsoidal melanosomes, and the other was composed of melanosomes with irregular sizes and shapes. Melanocytes seemed to be under necrosis, apoptosis, or dark cell transformation. Langerhans cells were found in the bulb. Two kinds of melanosomes were produced in the same hair bulb simultaneously. Degenerating melanocytes might produce deformed melanosomes. Langerhans cells might be involved in the death of melanocytes. It is unknown how either group of melanosomes is adopted and transferred to the hair cortex producing the characteristic pattern of pigmentation.     

Age-related changes in erythropoietin immunoreactivity in the cerebral cortex and hippocampus of rats

Although oxidative stress may influence the fluid properties of blood, resulting in a potential decrement in blood flow and oxygen delivery to the brain during aging, very little is known about age-related changes in Epo expression. Therefore, we examined age-related changes in Epo expression in the cerebral cortex and hippocampus with an immunohistochemical technique. In aged rats, there was a significant decrease in Epo immunoreactivity in the pyramidal cells in the cortical regions. In the hippocampus of adult rats, a distinct immunoreactivity pattern was observed in the CA1-3 areas and dentate gyrus. In aged hippocampus, Epo immunoreactivity was significantly deceased in the pyramidal layer of CA1 regions, and the granule cell layer of dentate gyrus. It was noted that there was distinct pattern of Epo immunoreactivity in the pyramidal layer of CA2-CA3 region of aged rats. Epo immunoreactivity was relatively strong, but was observed only in the periphery of the cytoplasm. The first demonstration of age-related decreases in Epo expression in the cerebral cortex and hippocampus may provide useful data for investigating the pathogenesis of age-related neurodegenerative diseases, suggesting that age-related decreases in Epo may contribute to degenerative events following age-related decreases in brain flow and oxygen supply.     

Metronidazole-induced encephalopathy

We report the clinical, neuropsychological, and neuroimaging findings of two patients of diffuse encephalopathy associated with the use of metronidazole. Both patients showed characteristic abnormalities on magnetic resonance imaging (MRI) with diffusion weighted imaging (DWI) and recovered incompletely after the discontinuation of metronidazole. We also suggest that MRI with DWI may be useful in the diagnosis of metronidazole-induced encephalopathy, and that they have a role in the prediction of prognosis.     

Control of encapsulation efficiency and initial burst in polymeric microparticle systems

Initial burst is one of the major challenges in protein-encapsulated microparticle systems. Since protein release during the initial stage depends mostly on the diffusional escape of the protein, major approaches to prevent the initial burst have focused on efficient encapsulation of the protein within the microparticles. For this reason, control of encapsulation efficiency and the extent of initial burst are based on common formulation parameters. The present article provides a literature review of the formulation parameters that are known to influence the two properties in the emulsion-solvent evaporation/extraction method. Physical and chemical properties of encapsulating polymers, solvent systems, polymer-drug interactions, and properties of the continuous phase are some of the influential variables. Most parameters affect encapsulation efficiency and initial burst by modifying solidification rate of the dispersed phase. In order to prevent many unfavorable events such as pore formation, drug loss, and drug migration that occur while the dispersed phase is in the semi-solid state, it is important to understand and optimize these variables.     

Sequential expression of inducible nitric oxide synthase and cyclooxygenase-2 during DMBA-induced hamster buccal pouch carcinogenesis

BACKGROUND: Although it is known that iNOS and COX-2 are abundantly expressed in oral premalignant and malignant lesions, respectively, the interaction between iNOS and COX-2 has not been extensively studied. The purpose of this study was to examine the alteration of the iNOS and COX-2 expression level during hamster buccal pouch (HBP) carcinogenesis. MATERIALS AND METHODS: The expression of both iNOS and COX-2 on normal, dysplastic mucosa and squamous cell carcinoma (SCC) from different differentiation stages in 7, 12-dimethylbenz[a]anthracene (DMBA)-induced HBP carcinogenesis was examined using immunohistochemical analysis. RESULTS: The mean values of both iNOS and COX-2 expression increased gradually from control to dysplastic lesions and more to invasive SCC. The highest mean expression was SCC. The differences between both iNOS and COX-2 expression in the normal and that in the dysplastic and carcinoma lesions were statistically significant. CONCLUSION: The results suggest that iNOS can enhance its ability to promote tumor growth in cooperation with COX-2. The expression of iNOS and COX-2 may be one of the factors that contribute to oral carcinogenesis.     

Postnatal risk factors of retinopathy of prematurity

To investigate the postnatal risk factors of retinopathy of prematurity (ROP), we analysed demographic and clinical data abstracted from the medical records of 425 premature babies who were examined for ROP between January 1994 and December 1998 at Asan Medical Centre, Seoul, Korea. ROP developed in 20.7% of the cases studied. A gestational age (GA) of < or = 28 weeks and birthweight (BW) of < or = 1000 g were the most significant risk factors. Ventilator care for > or = 48 h, apnoea, and use of surfactant independently increased the incidence of ROP. Furthermore, frequent apnoeic attacks increased the progression of pre-threshold ROP to threshold ROP. Therefore, as well as GA and BW, apnoea, prolonged use of a ventilator, and surfactant therapy are significant independent risk factors for ROP. In addition, apnoea may not only increase the risk of developing ROP, but may also worsen pre-existing ROP.     

Effect of L-carnitine supplementation on cardiac carnitine palmitoyltransferase activities and plasma carnitine concentrations in adriamycin-treated rats

Adriamycin (ADR) inhibits the carnitine palmitoyl transferase (CPT) system and consequently the transport of long-chain fatty acids across mitochondrial membranes. l-Carnitine (CARN) plays a major role in fatty acid oxidation by translocating activated long-chain fatty acids into the matrix of mitochondria. CARN has been shown to be of benefit in certain cardiac conditions including cardiomyopathy and myocardial infarction. This study was devised to investigate the effect of CARN on altered CPT I and CPT II activity in the cardiomyopathy associated with ADR therapy. We also assessed the effect of CARN on the plasma free, total, and acylcarnitine concentrations. Four groups, each consisting of four male Sprague-Dawley rats, were studied: group 1(n = 4) was not given either ADR or CARN; group 2 (n = 4) was given ADR (15 and 20 mg/kg, respectively, cumulative dose) by i.p. injections for 1 and 2 wk; group 3 (n = 4) was given the same dose of ADR with CARN (200 mg/kg); and group 4 (n = 4) was given CARN (200 mg/kg). The activities of CPT I and CPT II in heart were significantly decreased in the ADR-treated rats (p < 0.05) in a dose-dependent manner. The reduced activities of CPT I and CPT II, inhibited by ADR, were not normalized by supplementation with CARN (p < 0.05). In rats supplemented with CARN alone, the activities of CPT I and CPT II were elevated approximately 50% above those of the control rats (p < 0.05). ADR treatment resulted in elevation of plasma free and total CARN concentrations (p < 0.05). Supplementation with CARN did not effect the increased plasma CARN concentrations resulting from ADR treatment (p < 0.05). This study supports the concept that ADR toxicity results from the inhibition of both CPT I and CPT II activities and that one of the causes of ADR-induced cardiomyopathy is a result of globally impaired fatty acid oxidation.