3-D components of a biological neural network visualized in computer generated imagery. II. Macular neural network organization

Computer-assisted reconstructions of small parts of the macular neural network show how the nerve terminals and receptive fields are organized in 3-dimensional space. This biological neural network is anatomically organized for parallel distributed processing of information. Processing appears to be more complex than in computer-based neural networks, because spatiotemporal factors figure into synaptic weighting. Serial reconstruction data show anatomical arrangements which suggest that 1) assemblies of cells analyse and distribute information with inbuilt redundancy, to improve reliability; 2) feedforward/feedback loops provide the capacity for presynaptic modulation of output during processing; 3) constrained randomness in connectivities contributes to adaptability; and 4) local variations in network complexity permit differing analyses of incoming signals to take place simultaneously. The last inference suggests that there may be segregation of information flow to central stations subserving particular functions.     

Ovine maternal and fetal glomerular atrial natriuretic factor receptors: response to dehydration.

In pregnancy, dehydration produces marked effects on maternal and fetal body water homeostasis including an increase in fetal urinary sodium concentration and excretion. To examine the role of fetal plasma atrial natriuretic factor (ANF) and glomerular ANF receptors in dehydration-induced natriuresis, we compared plasma ANF levels and glomerular ANF binding characteristics in dehydrated and control maternal and fetal sheep. Mean (+/- SEM) maternal and fetal plasma ANF levels in control animals (n = 9) at 132-136 days gestation were 37 +/- 3 pg/ml and 138 +/- 20 pg/ml, respectively. Although mean ANF receptor maximum binding capacities (Bmax) were significantly higher in maternal than in fetal glomeruli (83 +/- 11 vs 34 +/- 12 fmol/mg protein, respectively), the dissociation constants (Kd) for ANF binding were not different (2.7 +/- 0.6 and 3.7 +/- 1.7 x 10(-10) M, respectively). In an additional 9 animals studied after 63 +/- 4 h of water deprivation, maternal plasma ANF levels were significantly lower than in the control group (14 +/- 4 vs. 37 +/- 3 pg/ml), maternal glomerular ANF receptor Bmax values were significantly higher (732 +/- 203 vs. 83 +/- 11 fmol/mg protein), and Kd values were six-fold higher (17.0 +/- 7.1 vs. 2.7 +/- 0.6 x 10(-10) M), although this difference was only marginally significant (p = 0.06). In contrast to the adult, there was a small, nonsignificant decrease in plasma ANF levels and no difference in Bmax or Kd values between the dehydrated and euhydrated fetal animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

A study of the heterogeneity of the mucoepidermoid tumor and the implication for future therapies.

Mucoepidermoid carcinomas are common head and neck neoplasms whose wide distribution includes the major salivary glands, especially parotid, the minor salivary glands within the oropharynx, sites within the larynx, and the submucosal bronchial glands. These tumors are heterogeneous neoplasms composed of intermediate, squamous, and mucous cell subpopulations and have been traditionally classified as low or high grade based on their histological nature and tendency for invasion and metastasis. To gain a better understanding of the heterogeneity of these tumors, we conducted in-depth studies of the different cellular subpopulations obtained from primary human mucoepidermoid carcinomas from various sites, and a derived cell line grown in monolayer culture and as a nude mouse xenograft. Flow cytometric and clonal dilution studies indicate that the intermediate cell behaves as a reserve cell capable of differentiating into either the squamous cell or mucous cell. Immunocytochemical studies of bromodeoxyuridine uptake and Ki-67 antigen expression indicate that whereas the squamous and mucous cells are terminally differentiated and permanently arrested in G0, the intermediate cell actively enters G1 and S. Studies of invasion utilizing a human amnionic membrane indicate that only the intermediate cell is capable of active invasion. Because the mucous and squamous cells are incapable of further division or invasion, therapeutic strategies aimed at differentiating the intermediate cell in vivo into either mucous or squamous directions would serve as useful adjuncts to surgery by reducing the rate of recurrence and the incidence of metastasis.     

Maternal HIV infection, drug use, and growth of uninfected children in their first 3 years

OBJECTIVE: To determine the separate effects of maternal HIV infection and drug use during pregnancy on growth of uninfected children in their first 3 years. DESIGN: Retrospective analysis of measurements from health visitor records made during routine child health surveillance at 6 weeks, 10 months, and 3 years of age. Multilevel analysis allowed for between-infant variation in fitted growth lines, and adjustment for other factors. Growth was described in terms of an intercept (z score at term) and growth slopes (change in z score per year) up to, and from, 4 months. SUBJECTS: 290 case babies delivered in Edinburgh hospitals to women who reported injection drug use by either themselves or their HIV infected partner, and 186 community controls. A total of 131 (45%) of the case babies were born to women who used drugs, predominantly opiates, during pregnancy and 93 (32%) to HIV infected women. The eight infected children were excluded from analysis. MAIN OUTCOME MEASURES: Age and sex standardised z scores for height, weight, and body mass index. RESULTS: 459 (96%) of the 476 records for cases and controls were traced, yielding 1432 weight and 939 height measurements. Maternal HIV infection was not found to affect growth; at 3 years the estimated effect on weight z score was 0.16 with 95% confidence interval (-0.25 to 0.57) and for height 0.18 (-0.19 to 0.55). Drug use during pregnancy was associated with lighter babies at 40 weeks followed by depressed growth in the first four months, these infants remaining just slightly smaller at 3 years with an estimated effect on z scores of -0.5 for weight with 95% confidence interval (-0.89 to -0.11) and -0.37 (-0.72 to -0.02) for height. CONCLUSIONS: Maternal HIV infection does not adversely affect growth in uninfected infants, and the effect of drug use during pregnancy is limited to small decrease in size at 3 years.     

Recurrent chest pain as the presenting manifestation of spinal meningioma

We report the case of a 9-year-old boy with a spinal cord meningioma whose only manifestations were recurrent episodes of chest pain lasting for 2 years. This case shows that spinal cord meningioma should be considered among the possible causative factors of chronic chest pain in childhood. Chest pain, meningioma, spinal tumors     

Noncovalent binding of a mitomycin C metabolite, 2,7-diaminomitosene, to duplex DNA

The major metabolite of mitomycin C, 2,7-diaminomitosene (DAM), interacts noncovalently with DNA. This was supported by ultraviolet-visible spectrum changes upon mixing with DNA and ethidium bromide displacement from DNA, measured as fluorescence changes. Moreover, DAM bound to DNA sufficiently strongly to hold DNA in a double stranded conformation under denaturing gel electrophoresis conditions commonly used to measure mitomycin C cross-links. These data show that generation of DAM and interaction with DNA represent a potential additional mechanism of DNA damage induced by mitomycin C.     

Squamous oesophageal cancer can be downstaged using protracted venous infusion of 5-fluorouracil with epirubicin and cisplatin (ECF)

21 patients with squamous oesophageal carcinoma were treated with a new regimen designed in our unit and effective in treating gastric adenocarcinoma, consisting of continuous venous infusion of 5-fluorouracil for up to 24 weeks (200 mg/m²/day) with epirubicin (50 mg/m²) and cisplatin (60 mg/m²) every 3 weeks. 12 patients (57%) had an objective response. The median relapse free period was 7 months, median survival from start of chemotherapy 8.4 months, and median survival from diagnosis, 14 months. Symptomatic improvements were reported by 10/11 patients with pain (91%), 8/9 with anorexia (89%), 8/10 with reflux (80%) and 10/14 with dysphagia (71%). Grade 3 or 4 toxicity was reported by 11 patients: 5 had haematological toxicity, 3 vomiting, 2 infection and 1 diarrhoea. One patient developed peripheral neuropathy, 1 renal impairment and another peripheral vascular disease. Following chemotherapy, surgery was attempted in 5 patients. One remains well 3 years on, 2 had macroscopic clearance of tumour but died of postoperative complications. In 2, disease was irresectable. This regimen of moderate toxicity is effective at improving symptoms in the majority of patients. In some patients, tumours are briefly downstaged so that inoperable tumours may become operable.     

Fractional allele loss data indicate distinct genetic populations in the development of non-small-cell lung cancer.

Allelic imbalance or loss of heterozygosity (LOH) has been widely used to assess genetic instability in tumours, and high LOH on chromosome arms 3p, 9p and 17p has been considered to be a common event in non-small-cell lung cancer (NSCLC). We have investigated allelic imbalance in 45 NSCLCs using 92 microsatellite markers on 38 chromosome arms. LOH of 38% was observed on 3p using nine markers, 58% on 9p using 15 markers and 38% on 17p using five markers. Fractional allele loss (FAL) has been calculated for each tumour (FAL is the number of chromosome arms showing LOH/number of informative chromosome arms) and a median FAL value of 0.09 was obtained in the 45 NSCLCs studied. The LOH data were examined on the basis of FAL scores: low FAL (LFAL) (0.00-0.04), medium FAL (MFAL) (0.05-0.13) and high FAL (HFAL) (0.14-0.45) based symmetrically around the median FAL value of 0.09. Tumours with HFAL values showed a very clear polarisation of the LOH data on chromosome arms 3p, 9p and 17p, such that 80% showed loss on 3p, 80% on 9p and 73% on 17p. These incidences of LOH were significantly higher than would be expected, since overall genetic instability in these HFAL tumours ranged from 14% to 45% LOH. Nine of the 14 patients in the LFAL group were found to have no LOH on 3p, 9p or 17p, but five of these had LOH at other sites: i.e. LOH on 5p, 5q, 8p, 13q, 16q and 19q. These results indicate that LFAL patients form a new subset of NSCLC tumours with distinct molecular-initating events, and may represent a discrete genetic population.     

Morphological evidence of vestibular pathology in long-term experimental diabetes mellitus. I. Microvascular changes

The influence of long-term experimental diabetes on the microvasculature of the saccule and utricle was investigated using quantitative light and electron microscopic techniques. Basal lamina thickening or reduplication, typically seen in diabetic microangiopathy, were not observed. However, morphometric analysis did reveal a statistically significant increase in capillary diameters along with an increased vascularization of both the saccule and utricle. Both of these microvascular abnormalities may have been caused by the hemodynamic alterations known to occur in diabetes. These alterations include decreased deformability of red blood cells and increased blood viscosity. Either of these factors can lead to a greater stress on the capillary wall and possibly to a reduced oxygen delivery to the tissues.