Ventral neural tube cells differentiate into hepatocytes in the chick embryo

A population of ventral neural tube cells has recently been shown to migrate out of the hindbrain neural tube via the vagus nerve and contribute to the developing gastrointestinal tract. Since liver is also innervated by the vagus nerve, we sought to determine if these cells also migrate into the liver. Ventral neural tube cells in the caudal hindbrain of chick embryos were tagged with a replication-deficient retroviral vector containing the LacZ gene on embryonic day 2. Embryos were processed for detection of labeled cells on embryonic day 5 and 11. Labeled cells were seen in the liver on both days and identified as hepatocytes. Previously, it was believed that all hepatocytes develop from the gut endoderm. Results of the present study show an additional source for the formation of liver cells.

Ventral neural tube cells differentiate into craniofacial skeletal muscles

Craniofacial skeletal muscle cells are believed to develop from mesoderm. A population of ventral neural tube cells has recently been shown to migrate out of the hindbrain and populate the craniofacial mesenchyme in chick embryos. Since skeletal muscle cells develop from this mesenchyme, we sought to determine if the emigrated neural tube cells contributed to their development. Ventral neural tube cells in the hindbrain of chick embryos were labeled on embryonic day 2 with replication-deficient retroviral vectors containing the gene LacZ, which provides a permanent marker for the progeny. On day 7 embryos were processed for the detection of labeled cells. Labeled cells were seen in craniofacial skeletal muscles. By using muscle-specific markers, the labeled cells were confirmed to be skeletal muscle cells. Thus, some muscle cells are derived from the ventral neural tube cells of the hindbrain.

Emigration of neuroepithelial cells from the hindbrain neural tube in the chick embryo

It is generally believed that after the emigration of neural crest, the neuroepithelial cells of the neural tube are committed to differentiate only as neurons and supporting cells of the central nervous system. Neural crest cells arise from the dorsal portion of the developing neural tube and contribute to the formation of the peripheral nervous system and a variety of non-neural structures. In contrast to this view we have recently shown, by focal application of the vital dye Dil in duck embryos, that an additional population of cells emigrates from the neural tube. By using an entirely different technique we confirm and extend these observations in the chick embryo. Replication-deficient retroviral vector LZ12 containing the gene LacZ was utilized to label the neural tube cells. The viral concentrate was microinjected into the lumen of the rostral hind-brain neural tube, considerably after the completion of emigration of neural crest cells. The labeled cells were monitored in whole mounts and histological sections. Initially, the labeled cells were restricted to the neuroepithelium of the hindbrain neural tube. Subsequently, they were seen in the neural tube and in the ganglion of the fifth cranial nerve (trigeminal ganglion). Later, they migrated beyond the trigeminal ganglion, i.e., into the mesenchyme of the first pharyngeal arch. Immunostaining with the neural crest cell marker, HNK-1, indicated that the emigrated neuroepithelial cells were HNK-1 negative. It is concluded that in the chick embryo some neuroepithelial cells emigrate at the site of attachment of the trigeminal nerve, migrate into the ganglion and then into the mesenchyme of the first arch. This cell population differs antigenically from the neural crest cells.

Red cell distribution width (RDW) changes in pregnancy

OBJECTIVE

As part of an exercise in establishing normograms of hematological parameters in pregnancy, we studied the red cell distribution width (RDW) in healthy pregnant women.

METHODS

A longitudinal study of RDW measurements in 121 pregnant women at 16 and 34 weeks gestation and during labor and at Days 3 and 7 postpartum. All the women had uncomplicated pregnancies, minimum hemoglobin (Hb) of 11.0 g/dl at recruitment and took iron supplements from 16 weeks of gestation and until 7 days after delivery. All subjects went into spontaneous labor, 110 achieving a normal vaginal delivery while the remaining 11 were delivered by cesarean section. Two-way analysis of variance was used to study the changes in RDW between any given gestations to test the variability between and within subjects.

RESULTS

RDW increased significantly (P < 0.0001) between 34 weeks of gestation and the onset of labor. No significant changes occurred between 16 and 34 weeks gestation, or during the 7 days postpartum.

CONCLUSION

This is the first longitudinal study analyzing the between and within women changes in RDW with progression of pregnancy. The unexpected rise in the RDW during the last 4-6 weeks leading up to the onset of labor suggests increased bone marrow activity. The stimulus is unknown, but as RDW changes are highly significant there may well be a useful indicator of impending parturition.

The supplementation of levothyroxine among indigenous people in endemic goitre areas: The impact of therapy

In order to study the effect of levothyroxine in the treatment of endemic goitre, a longitudinal study was conducted among the Aborigines in Lanai Post and Sinderut Post, situated in an iodine-deficient area located in the district of Kuala Lipis, Pahang. All subjects in the treatment group (Lanai Post) were given 100 µg of levothyroxine per day and were followed for 1 1/2 years. A total of 311 subjects were examined at baseline, 323 on the first, 256 on the second, 239 on the third and 184 on the fourth visit following levothyroxine supplementation. Goitre prevalence, thyroid hormones, thyroid volume, nutritional status, urinary iodine levels, arterial blood pressure and mental performance were determined. Following the intervention, goitre prevalence was significantly reduced in the treatment group (baseline 42.8% vs final visit 13.0%, p<0.0001); however, no significant difference was noted in the control group. Total T4 levels were increased in the treatment group (p<0.0001), while a significant reduction was noted in the control group (p<0.0001). Thyroid-stimulating hormone levels increased significantly in the treatment group following 1 year of intervention, while no significant changes were observed in the control group. As for the thyroid volume, both groups showed a significant increment following the intervention (p<0.0001). With respect to the nutritional status, the treatment group showed a significant increase in body weight following the intervention (p<0.05). In addition, the mid-arm circumference and body mass index also increased after 1 year of intervention. However, the control group showed a reduction in the waist-hip ratio (p<0.0001). Although there was no statistical difference in the waist-hip ratio in the treatment group, there has been a significant reduction observed after 1 year of intervention. At 1 year, a reduction in skinfold thickness was noted in the treatment group while only the triceps and subscapular were increased in the control group. The body fat was decreased in the treatment group following 1 year of intervention (p<0.0001). No particular trend was noted in the urinary iodine excretion in the treatment group, but surprisingly, the levels were increased in the control group (p<0.0001). A significant increase in both systolic and diastolic blood pressures was observed in the treatment group following 1 year of intervention, but the controls showed a reduction in the systolic blood pressure (p<0.0001). Both groups showed a remarkable increase in mental performance, with a more pronounced effect in the treatment group (p<0.05). The correction of iodine deficiency by levothyroxine supplementation has a short-term beneficial effect in reducing the prevalence of goitre and improving the mental ability among the Aborigines in endemic areas; however, proper monitoring and close supervision are needed to maintain compliance.

A standardized form for weekly check of therapy charts

A form for the weekly physics check of therapy charts by the Physics staff has been developed. It is found to be a time saving and quality improvement tool.

Elimination of alkaline phosphatases from circulation by the galactose receptor. Different isoforms are cleared at various rates

Three isoforms of human alkaline phosphatase (liver, bone and placental ALP) were purified and their elimination studied after intravenous injection in rats. The rates of elimination were significantly inhibited by prior injection of asialofetuin, indicating that the uptake was mediated by the galactose receptor in liver. Their relative clearance rates differed, being rapid for the bone ALP, significantly slower for the liver isoform and very slow for the placental ALP. The bone ALP showed a rapid initial clearance, apparently related to its large glycan heterogeneity and to the presence of molecules with a low sialic acid content. When isolated from serum the liver and bone ALP isoforms showed clearance rates differing slightly from those of the organ derived forms. We conclude that differences in carbohydrate structure and amount of sialic acid of the three isoforms result in various clearance rates. These differences will also affect their serum concentrations as well as the composition and heterogeneity of the individual isoforms in serum.

Comparative microanatomy of the lateral wall of the 'cavernous sinus' in humans and the olive baboon

Despite many studies of the 'cavernous sinus' lateral wall, the anatomy of this area remains controversial. We performed a comparative microanatomical and histoarchitectural study in 14 humans and in 10 nonhuman primates (Papio cynocephalus anubis). Venous channels and cranial nerves were embedded in the 'interperiosteodural space'. The dura propria of the lateral wall could be removed without entering the venous compartment. The oculomotor and trochlear nerves were accompanied by an arachnoidal and dural sheath. The oculomotor nerve sheath stopped under the anterior clinoid process in baboons. The trigeminal ganglion was covered posteriorly with an arachnoid membrane and adhered firmly to the dura propria on lateral and anterior sections. The three branches of the trigeminal nerve had no arachnoid covering, except for arachnoid granulations in humans. In baboons, the oculomotor and trochlear nerves were thicker than in humans, while the ophthalmic nerve was thinner. The abducens nerve belonged to the lateral wall of the sinus in baboons and had no arachnoidal sheath except in the first millimeters of Dorello's canal. After leaving their arachnoidal and dural sheath, the intracavernous cranial nerves acquired a typical peripheral sheath. The venous channels in both species were true dural sinuses. Willis cords and adipose tissue were identified.

A cranio-cervical malformation presenting as acute respiratory failure

An 18-year-old, previously healthy male presented with bilateral pneumonia and acute respiratory failure with severe carbon dioxide retention. The presence of mild brainstem signs and hypoventilation led to the discovery of a platybasia, basilar invagination, and kinking of the medulla oblongata with early syrinx. He was operated upon but postoperatively was noted to have a mixed type of sleep apnea. This case illustrates the diagnostic challenge in acute respiratory failure in a previously healthy young person and the possible pathogenic mechanisms underlying it.

DiI labeling and homeobox gene islet-1 expression reveal the contribution of ventral neural tube cells to the formation of the avian trigeminal ganglion

Cells of the neural tube are thought to be committed to form only the central nervous system, whereas the peripheral nervous system is believed to be derived from neural crest cells and from placodes, which are specialized regions of the surface ectoderm. Neural crest cells arise early from the dorsal part of the neural tube. The possibility that after emigration of the neural crest cells, another population of cells arising from the ventral part of the neural tube also emigrates via a different route was examined. Here we report that, after labeling cells of the ventral neural tube in the rostral hindbrain of E3 duck embryos with DiI, they were later found in the trigeminal ganglion of the fifth cranial nerve. A trail of labeled cells could be traced from the ventral part of the neural tube to the peripheral ganglion. Further, expression of the homeobox gene Islet-1 in cells of the neural tube and the ganglion also indicated that some ventral neural tube cells may normally emigrate to the trigeminal ganglion. It is concluded that not all neural tube cells are committed to form the central nervous system; the ventral part of the neural tube also provides cells for the formation of the trigeminal ganglion. These results raise the possibility that the ventral neural tube may serve as an additional source of cells for the formation of various other components of the peripheral nervous system.

Radiation alone for carcinoma of the vagina: variation in response related to the location of the primary tumor

BACKGROUND

A retrospective study of 40 patients with histologically confirmed carcinoma of the vagina is reported. The patients were treated by radiation alone (a combination of external beam therapy and implants) between October 1969 and September 1991 at the Medical College of Virginia Hospital in Richmond.

METHODS

Thirty-three patients (82%) had squamous cell carcinoma, 2 patients (7%) had adenocarcinoma, and 2 patients (5%) had poorly differentiated cancers (1 melanoma and 1 leiomyosarcoma). The patients were staged according to the International Federation of Gynecology and Obstetrics (FIGO) staging system; there were 13 patients (33%) in Stage 1, 21 (52%) in Stage II, 4 (10%) in Stage III, and 2 (5%) in Stage IV. Thirty-six patients (90%) were treated with external beam therapy and some combination of implant: cylinder, ovoid, or interstitial implants with iodine-125 or iridium-192 (afterloading). Only 4 patients (10%) received treatment by implant only.

RESULTS

Based on their response, two groups of patients were identified. Group I had 23 patients with tumors predominantly located in the proximal half of the vagina; there were 8 patients in Stage I, 11 in Stage II, 3 in Stage III, and 1 in Stage IV. Of these, three patients failed: one each in Stages III and IV and one Stage II patient was salvaged by surgery. Three patients died due to unrelated causes but with local control. The 5-year actuarial survival in this group was 81%. Group II had 17 patients with tumors located in the mid to distal half of the vagina; there were 5 patients in Stage I, 10 in Stage II, and 2 in Stage IV. Ten patients failed. Eight patients in Stage II had persistent disease, were lost to follow-up, and are presumed dead. Two patients with Stage IV disease also had inadequate local control. The overall actuarial survival in the distal group was 41%, which was significantly worse than the proximal group (81%), at a P value of 0.05.

CONCLUSIONS

This study discusses the curability of carcinoma of the vagina based on its anatomic location when predominantly similar treatment techniques and radiation doses were applied to either the proximal or the distal part of the vagina, those with cancer in the proximal half had better survival (81%) than those whose cancer was in the distal half (41%).

Dependence of cranial motor neuron formation on ventromedial brain stem

The formation of motor neurons in the spinal cord is dependent on inductive signals from the floor plate and notochord. Motor neurons in the brain stem, on the other hand, develop in the absence of both structures. This suggests that either the germinal epithelium is specified intrinsically to form specific cranial motor nuclei or that the inductive signals for the formation of cranial motor neurons arise from some other structure. These possibilities were investigated experimentally by using the formation of trochlear motor neurons in the midbrain of duck embryos as a model system. The trochlear motor neurons, which form the nucleus of the fourth cranial nerve, developed normally after early damage to the prospective germinal epithelium, suggesting that it is unlikely to be specified intrinsically to form these cranial motor neurons. Instead, their development was found to be dependent on the cells within, or associated with, the ventromedial region of the brain stem, as the extirpation of this region results in the absence of motor neuron formation. These results show that structures other than the floor plate and notochord provide inductive signals for the cellular differentiation and patterning of the developing central nervous system. The raise the possibility that the inductive signals for motor neuron differentiation in the spinal cord and the brain stem may not be necessarily identical.

Levels of thyroxine, TSH, thyroid volume and mental performance among Orang Asli in selected settlements in Malaysia

A significant difference in the levels of thyroxine (T4), thyroid stimulating hormone (TSH) and thyroid volume among settlements at various selected Orang Asli locations is reported. The levels improved according to the level of socio-economic development. No significant difference was found in mental performance by location.

The effectiveness of annual versus biennial mass chemotherapy in reducing morbidity due to schistosomiasis: a prospective study in Gezira-Managil, Sudan

The most serious complication of schistosomiasis is periportal fibrosis, which affects a large number of subjects in endemic areas. Population-based chemotherapy remains the most effective way of controlling this disease. In an attempt to find the best way to deliver chemotherapy to the endemic population, we compared the impact of repeated annual versus biennial mass chemotherapy on morbidity due to schistosomiasis in two villages in Gezira, Sudan. One village was given five rounds of mass chemotherapy annually in the years 1990-1994 while the other village was given three rounds of mass chemotherapy biennially from 1988 to 1994. Before treatment, these villages had similar intensity of infection and prevalence. One round of either annual or biennial treatment reduced the intensity of infection, but not prevalence or morbidity. After two rounds of annual chemotherapy, infection rates, bloody diarrhea, and fibrosis in those 20 years of age and less were significantly reduced. Two rounds of biennial chemotherapy had a similar effect on rates and bloody diarrhea; however, fibrosis was reduced only after the third round of biennial chemotherapy. Prevalence of hepatosplenomegaly increased after both treatment regimens. Reinfection was most prominent in those 5-14 years of age. These findings support the general notion that repeated chemotherapy may be needed in areas of high transmission of schistosomiasis. We recommend two rounds of annual mass chemotherapy to significantly reduce infection and morbidity.

Formation of the cranial motor neurons in the absence of the floor plate

The inductive signals for the differentiation of motor neurons in the spinal cord have been experimentally shown to arise from cells in the midventral region of the neural tube, often referred to as the floor plate, and from the notochord. Although the prevailing view is that a similar mechanism accounts for the differentiation of motor neurons in the brain stem, supporting experimental evidence is lacking. Here, using the formation of the trochlear nucleus in the midbrain of duck embryos as a model system, we report that the floor plate and the notochord are not necessary for the development of these motor neurons in the brain stem. Early damage to the floor plate or extirpation of the floor plate and notochord does not prevent the development of these cranial motor neurons. Thus, either the inductive signals for the formation of these cranial motor neurons arise from some other structure or the germinal epithelium of the cranial neural tube is intrinsically programmed to form specific cranial motor nuclei.

Community based distribution of ivermectin in eastern Sudan: acceptability and early post-treatment reactions

A study to monitor ivermectin acceptability and post-treatment reactions during mass community distribution was carried out in eastern Sudan, where severe reactive onchodermatitis is prevalent. Of 1081 individuals eligible for treatment, 1076 (99.5%) accepted the ivermectin. Post-treatment reactions were monitored by self reporting, 5 d after a single dose of about 150 micrograms/kg (range 103-200 micrograms/kg); 230 persons reported adverse events (21.4%). No reaction was rated as severe. The most common problem was itching with cutaneous papular eruptions (16.2%). Local oedematous swelling was the second most common and the most slowly resolving complaint (5.4%), followed by musculoskeletal pain. There was a high acceptance rate of the treatment and remarkable tolerance of the post-treatment effects, probably due to efforts made to prepare the community to expect reactions to ivermectin, widespread awareness of the beneficial effects of treatment by villagers who had participated in clinical trials previously, and the encouragement we gave to the population to become involved in improvement of their health care services. Single doses of ivermectin resulted in good clinical responses and created much goodwill among villagers. Improvements in physical fitness, ability to work, and freedom from musculoskeletal pain were reported at the 3 months' follow-up. We recommend that, during mass distribution of ivermectin, community involvement in planning overall health improvement should be included, since the treatment initiates the process well. In areas where sowda syndrome is prevalent, medical surveillance for 3 d or more should be considered.

Ivermectin treatment in severe asymmetric reactive onchodermatitis (sowda) in Sudan

Ivermectin efficacy and post-treatment reactions in asymmetric severe reactive ochodermatitis (sowda) were studied in 8 patients with sowda syndrome and 6 with mild generalized onchodermatitis in Sudan. Initial skin snips from 12 patients contained microfilariae (1-9 per mg skin). Patients were treated in hospital with a single oral dose of c. 150 micrograms/kg ivermectin (103-200 micrograms/kg) and monitored for frequency and severity of post-treatment reactions for 4 weeks. Serial samples of heparinized blood were collected over the first 24 h after treatment for determination of ivermectin pharmacokinetics. Skin snips from all patients on days 3 and 28 revealed no microfilariae. Post-treatment reactions were more common and severe in individuals with sowda; they consisted mainly of musculoskeletal pain, local swellings with pitting oedema, and lymph gland tenderness and enlargement. No relation was established between these reactions, the microfilarial infection intensity, or the plasma pharmacokinetic profiles. A single oral dose of ivermectin cleared the skin of microfilariae and led to improvement of symptoms and dermatological signs of sowda, but resulted in more marked reactions than in cases of generalized onchodermatitis.

Effect of neonatal monosodium glutamate on lipid peroxidation in adult rat brain

Glutamate (glu), an excitatory amino acid (EAA) abundantly present in the brain of mammals, is also a neurotoxin. We examined lipid peroxidation (LPO) potential and antioxidant parameters of midbrain region (MBR) and frontal cortex of adult rats following treatment with monosodium glutamate (MSG) during postnatal day (PND) 1 through PND 10 at a daily dose of 4 mg g-1 body weight. In PND 90 rats MSG increased LPO by 56% and altered antioxidant status of MBR. This indicates that oxidative stress produced by glu in vulnerable brain regions may persist for prolonged periods and could be one of the mechanisms of EAA neurotoxicity resulting in chronic neurodegeneration.

Pharmacokinetic interaction between praziquantel and albendazole in Sudanese men

It has been suggested that praziquantel (40 mg/kg) and albendazole (400 mg) administered together may have a synergistic effect on intestinal parasites. In the present study, the pharmacokinetics of these agents, alone and in combination, were investigated in the presence and absence of food in two groups of Sudanese males. The results indicated that praziquantel pharmacokinetics were not effected by co-administration of albendazole although, in the presence of food, the area under the curve (AUC(0-infinity)) of praziquantel increased 2.6 fold. The AUC(0-infinity) of albendazole sulphoxide (the active metabolite of albendazole) increased 4.5-fold when administered with praziquantel, eight-fold when given with food and 12-fold when given with praziquantel and food. The balance between the therapeutic efficacy of this combination of drugs and its safety profile needs to be studied, especially with regard to albendazole.