Ectopic expression of Hoxa-1 in the zebrafish alters the fate of the mandibular arch neural crest and phenocopies a retinoic acid-induced phenotype

Considerable evidence has demonstrated that retinoic acid influences the formation of the primary body axis in vertebrates and that this may occur through the regulation of Hox gene expression. In this study, we show that the phenotype induced by exogenous retinoic acid in the zebrafish can also be generated by the overexpression of Hoxa-1 following injection of synthetic RNA into the fertilised egg. The isolation, sequence and expression pattern of the zebrafish Hoxa-1 gene is described. We show that exogenously applied retinoic acid causes the ectopic accumulation of Hoxa-1 message during gastrulation in the hypoblast in the head region. Overexpression of Hoxa-1 following injection of RNA causes abnormal growth of the anterior hindbrain, duplication of Mauthner neurons in rhombomere (r) 2 and fate changes of r2 mesenchymal and neurogenic neural crest. These results are discussed in terms of the role of Hoxa-1 in controlling anterior hindbrain patterning and the relationship between expression of Hoxa-1 and retinoic acid.     

Esophagogastrectomy: reoperation for complications

We investigated various factors related to secondary hyperparathyroidism among hemodialysis patients. Subjects were 26 patients (20 men and 6 women) ranging in age from 24 to 75, treated at an ordinary hemodialysis center throughout the year 1991. The serum inorganic phosphate level and serum intact PTH level varied greatly from 2.5 to 12.5 mg/dl and from 10 to 1,102 pg/ml (normal range, 10-60 pg/ml), respectively. All patients were classified according to the serum intact PTH level into two groups: those with less than 120 pg/ml (Group I) and those with 120 pg/ml or more (Group II). The patients in Group I responded well to hemodialysis and drug therapy, but those in Group II were likely to have secondary hyperparathyroidism. In all patients in Group II, the PTH level increased markedly in the summer. This may be attributed to insufficient ingestion of calcium, vitamins, and other nutrients due to loss of appetite.     

Influence of the blight of Morinda officinalis How on microscopic structure and constituents of the host

The results showed that microscopic structure in biennial roots, the contents of B and Mn in nutritive organ and beta-sitosterol content in roots, stems of Morinda officinalis were affected markedly. The total sugar content in the roots and aerial stems was decreased by 5.42%-15.29%.     

Chronic growth stimulation of human adult melanocytes by inflammatory mediators in vitro: implications for nevus formation and initial steps in melanocyte oncogenesis

In the human epidermis, melanocytes are distributed at a distance from each other. In contrast, melanocytes in nevi, which are considered benign neoplasms of melanocytes, are grouped in nests. Although still not well defined, environmental factors are thought to play an important role in the development of nevi. We found that chronic growth stimulation by leukotriene C4, a compound found in increased amounts in inflamed skin, induced pleiotropic modifications in the normal melanocyte phenotype. These changes include loss of contact inhibition and formation of structures resembling tumor spheroids. In parallel with these changes, there was a constitutive expression of Fos protein. Switching these cultures to medium supplemented with phorbol ester sustained growth with reversion of the altered phenotype. In contrast, a cAMP stimulator, cholera toxin, induced features of terminal differentiation. Our findings suggest a role for inflammatory mediators in human epidermal melanocytes. This observation provides insight into melanocyte growth alterations which may have relevance in early stages of melanocyte oncogenesis.     

Effects of different natural stimulants on the activity of the rabbits' carotid chemoreceptor

The effects of different natural stimulants on the afferent unit discharge of rabbit carotid chemoreceptors were studied in the in vitro carotid body- sinus nerve preparation. A total of 32 chemoreceptive units were recorded. The results were as follows: (1) Of the 32 units, 10 (31%) showed chemosensory responses only to PO2 decrease; 9 (28%) to all stimulants (PO2 decrease, PCO2 increase and pH decrease); 9 (28%) to PO2 decrease and PCO2 increase; 3 (9%) to PO2 decrease and pH decrease; only one to pH decrease. (2) The potency of the three natural stimulants in eliciting the changes in intensity of discharge showed a decreasing order as follows: PO2 decrease > PCO2 increase > pH decrease. The above results suggest that the carotid body may contain only one or a combination of 2 or 3 kinds of chemoreceptors respectively sensitive to decrease PO2 to increase PCO2 or decrease pH.     

Fatal acute pulmonary oedema after inhalation of fumes from polytetrafluoroethylene (PTFE)

The cases of three patients with acute pulmonary oedema caused by inhalation of fumes from heated polytetrafluoroethylene (PTFE) in a plastic factory are described. One patient died from profound hypoxaemia and shock shortly after admission, and the other two patients survived after medical treatment. This is the first report of fatal pulmonary oedema in a worker exposed to PTFE heated in a plastic extruding operation. From this observation, it appears that inhalation exposure to pyrolytic products from polytetrafluoroethylene can cause fatal respiratory complications. Special precautions are warranted in this kind of operation to prevent workers from being exposed to these substances.     

Permeability change and brain tissue damage after intracarotid administration of cisplatin studied by double-tracer autoradiography in rats

The present study was designed to find the reliable parameter(s) for the detection of early neurotoxicity following intracarotid (IC) administration of cisplatin. IC administration was performed for 60 minutes in female Wistar rats derived into four groups according to the dose given (1 mg, 1.2 mg, and 1.5 mg of cisplatin, and normal saline in control rats). Blood-brain barrier (BBB) permeability and local cerebral blood flow (LCBF) were measured by a double-tracer autoradiography technique using 1-[14C]-alpha-aminoisobutyric acid (14C-AIB) and 4-[18F] fluoroantipyrine (18F-FAP), respectively. Blood chemistry and neuropathology were also examined. BBB permeability was increased only on the ipsilateral side. This increase was dose-dependent, preceded the brain necrosis, and was statistically significant in the hypothalamus (1.2 mg group), auditory cortex and caudoputamen (1.5 mg group). Renal dysfunction was often observed. The changes in the LCBF did not occur until brain necrosis was noticeable. These findings demonstrate that the increase in the BBB permeability provides a sensitive and reliable indication of an early toxicity to brain tissue following IC administration of cisplatin.     

Cocaine augments contractility of the pregnant human uterus by both adrenergic and nonadrenergic mechanisms

Airbag injuries have resulted in the deaths of several infants and small children, and such deaths are generally associated with rearward-facing infant seats or unrestrained children in front passenger seats of cars equipped with airbags. An airbag can also cause death in a small child wearing a shoulder/lap belt, however, as this case report illustrates. A two-year-old female was involved in a low-speed collision while riding in the front passenger seat of a dual-airbag-equipped automobile. Secondary impact with the airbag caused catastrophic occipitoatlantoaxial disarticulation with traumatic spinal cord separation, thermal injury and abrasions of the right forearm and distinctive patterned abrasions of the face. The possibility of airbag injury should be considered in all low-speed traffic fatalities, and the confirmatory injuries sought at postmortem examination.