Corneal epithelial recovery following photorefractive keratectomy

AIMS: To further understand the morphological and functional recovery of corneal epithelium following excimer laser photorefractive keratectomy (PRK). METHODS: The right eyes (group 1) of 15 male, New Zealand white rabbits weighing 2-3 kg underwent PRK. The left eye of each rabbit (group 2) underwent simple mechanical de-epithelialisation and were examined as treated controls. Both eyes of another eight rabbits (group 3) served as untreated controls. All eyes underwent a corneal epithelial permeability study by fluorophotometry at 2, 4, and 8 weeks after surgery. Five animals in groups 1 and 2 were sacrificed at 9, 10, and 12 weeks after surgery. The animals in group 3 were sacrificed at the end of the 12 week experimental period. Both eyes of each sacrificed animal were enucleated immediately and processed for both haematoxylin and eosin stain and electron microscopic study. The electron micrograph was magnified to 14,000x and the extent of hemidesmosome formation was quantified and analysed. RESULTS: The corneal epithelial barrier to sodium fluorescein was subnormal and returned to a normal barrier state 4 weeks after PRK in group 1 whereas it was normal in group 2 throughout the examination period. The extent of hemidesmosome formation was abundant yet subnormal in both groups 1 and 2 up to 12 weeks, when compared with that in group 3. CONCLUSION: The corneal epithelium regained its functional barrier 4 weeks after PRK in rabbits while the extent of hemidesmosome formation was still subnormal 12 weeks after mechanical de-epithelialisation, with or without PRK.     

Hematopoietic effects and clinical uses of granulocyte-macrophage colony-stimulating factor and PIXY321

We tested the influence of in vivo volume resuscitation on intrinsic contractile properties of left ventricular (LV) preparations of endotoxemic guinea pigs. Escherichia coli endotoxin (LPS)-injected animals were divided into nonresuscitated and resuscitated groups. Volume resuscitation improved cardiac output and stroke volume, increased arterial pH and body temperature, and decreased mortality. In isovolumetric LV preparations isolated 4 h after LPS injection, LV systolic pressures (in mmHg) preparations isolated 4 h after LPS injection, LV systolic pressures (in mmHg) of LPS with (42 +/- 3) and without (42 +/- 2) fluid resuscitation were consistently less than control values (70 +/- 3). LV end-diastolic pressure-volume (compliance) decreased in LPS-nonresuscitated hearts, while LV compliance of LPS-resuscitated hearts was similar to control. Thus, intravascular volume expansion selectively improved LV diastolic compliance of LPS hearts without affecting LV systolic function. These findings suggest that LV systolic and diastolic dysfunctions associated with endotoxemia and Gram-negative sepsis may involve separate pathogenic mechanisms.     

Evaluating ovarian reserve: follicle stimulating hormone and oestradiol variability during cycle days 2-5

A prospective measurement of follicle stimulating hormone (FSH) and oestradiol between cycle days 2 and 5 was conducted to investigate the intra- and inter-cycle variability in a healthy population of women with regular menstrual intervals. Daily serum samples were obtained from 44 women for a total of 66 cycles on cycle days 2, 3, 4 and 5. FSH concentrations were consistent on all cycle days measured. Oestradiol concentrations on cycle day 2 were not different from cycle day 3, but concentrations on cycle day 4 and cycle day 5 were statistically different from both cycle day 2 and cycle day 3 by analysis of variance (P < or = 0.05). Evaluation of functional ovarian reserved by cycle day 3 FSH measurement has become the standard in most assisted reproductive technology programmes. The recent change in FSH standardization coupled with the inflexibility of cycle day 3 testing has led to a re-evaluation of testing protocols. Cycle day 3 appears to have emerged as a dictum because most ovulation induction protocols are initiated on cycle day 3, 4 or 5. Flexibility of sampling day can be introduced as suggested by these results. The additional information ascertained from oestradiol testing as applied to evaluation of ovarian reserve warrants further investigation.     

Chromogranin A: its clinical value as marker of neuroendocrine tumours

Pigmentation is a well recognised adverse effect of minocycline therapy. Various body sites, most notably the skin, nails, bones, thyroid, mouth and eyes are affected and the pigmentation may appear at multiple sites. In general, pigmentation results from long term administration of minocycline at cumulative doses greater than 100 g, although cutaneous or oral mucosal pigmentation may appear, regardless of dose or duration of therapy. When the skin is involved, the blue-black pigmentation develops most frequently on the shins, ankles and arms. Other patterns of skin involvement include pigmentation that is either generalised and symmetrical, or that develops at sites of inflammation. The bones of the oral cavity are probably the most frequently affected sites of pigmentation affecting greater than 20% of patients taking minocycline for more than 4 years. In contrast, the oral mucous membranes and teeth are infrequently pigmented from minocycline. Ocular, thyroid and visceral pigmentation is also relatively uncommon and usually develops only with high doses and long term minocycline use. Whereas pigmentation of the skin and oral mucosa is generally reversible when the drug is discontinued, the pigmentation is often permanent when other sites are involved. Although minocycline-induced pigmentation is not harmful, the drug should be discontinued when the adverse effect is recognised. All patients receiving minocycline, especially those treated for longer than 1 year, require screening for the development of pigmentation.     

Cognitive, adaptive, and behavioral characteristics of Williams syndrome

The difference of morphological injury between rabbit aorta and pulmonary artery was compared after the animal was exposed to the altitude 5 km (PO2 = 10.8 kPa) for 24 h. Hypoxia caused subendothelial edema, increased vacuoles and injured mitochondria and endoplasmic reticulums in both kinds of endothelial cells. The impairment of pulmonary artery was obviously more severe than aorta and its smooth muscle cells were also affected. Forthermore, the exposure increased mitochondria in pulmonary artery endothelial cells. Bubbled with a mixture air of 95% N2-5% CO2 (PO2 = 4 kPa) led to an increase of pulmonary in tension, while hypoxia to the same extent induced aorta relaxation. These results indicate that hypoxia produces the differential effects on these two kinds of vessels, providing a possible explanation for the production of hypoxic pulmonary hypertension.     

Allergen immunotherapy inhibits airway eosinophilia and hyperresponsiveness associated with decreased IL-4 production by lymphocytes in a murine model of allergic asthma

Microelectrode recording methods for stereotactic localization of the subthalamic nucleus (STN) and surrounding structures are described. These methods accurately define targets for chronic deep brain stimulation in the treatment of Parkinson's disease. Mean firing rates and a burst index were determined for all recorded neurons, and responses to active and passive limb and orofacial movements were tested. STN neurons had a mean firing rate of 37+/-17 Hz (n = 248) and an irregular firing pattern (median burst index, 3.3). Movement-related activity and tremor cells were identified in the STN. Ventral to the STN, substantia nigra pars reticulata neurons had a mean rate of 71+/-23 Hz (n = 56) and a more regular firing pattern (median burst index, 1.7). Short trains (1-2 seconds) of electrical microstimulation of STN could produce tremor arrest but were not found to be useful for localization. Compared with data from normal monkeys our findings suggest that STN neuronal activity is elevated in Parkinson's disease.     

Twins, placentas, and genetics: acardiac twinning in a dichorionic, diamniotic, monozygotic twin gestation

We describe a human acardiac twin with associated vascular anastomoses in a dichorionic diamniotic fused twin placenta. A 22-year-old woman delivered a healthy 3,554 g male infant and a fused diamniotic dichorionic twin placenta with a 230 g umbilical cord-attached, skin-covered, ovoid mass, consistent with acardiac amorphus. By gross and histological examination, the placental dividing membranes comprised four leaves, one amnion from each placenta, and two centrally fused chorions, diagnostic of dichorionicity. Placental barium injection of the normal twin's umbilical vein showed an anastomosis with the acardiac twin which traversed the dividing membranes, then supplied major vessels of the acardiac mass via its 5.5 cm umbilical cord. DNA-typing studies of the normal twin's placenta and of the acardiac twin's tissues revealed identical alleles at 11 distinct genetic polymorphic loci, consistent with monozygosity. Our findings demonstrate that vascular anastomoses can occur in dichorionic twin placentas, and that human acardiac twinning is not, as heretofore believed, restricted to monochorionic placentas.