Lymphatic corrosion casts in rabbit ileum: scanning electronmicroscopic studies

AIM

To investigate the three-dimensional organization and fine distribution of the lymphatics in rabbit ileum.

METHODS

Lymphatic corrosion cast with the Mercox were used for scanning electron microscopy (SEM), and semithin sections were used for light microscopy. The Mercox injected intraparenchymally into ileum wall were cut and put in a concentrated NaOH solution until the tissues were corroded away, and observed under SEM.

RESULTS

The central lacteals were found in the intestinal villi. The villi of the ileum contained two to three lacteals. The central lacteals were drained into the mucosal lymphatic capillary plexus. From the plexus, the lymphatic capillary descended into the lymphatics of submucosal layer and muscular layer. Then they were led into the serosal lymphatics and drained into the lymphatics of intestine mesentery. The cast of the lymphatics showed an appearance of a string of heads and the notch corresponding to the bicuspid valve of the lymphatics.

CONCLUSION

The three-dimensional organization of central lacteals and lymphatics in the rabbit ileum is demonstrated by lymphatic corrosion casts. Numerous impressions of the endothelial nuclei, rich central lacteals and lymphatic capillary plexus in the ileum mucosa, lymphatic capillary and lymphatics in the submucosa and muscular layer are observed on the lymphatic corrosion cast.

PET and MRI of the thalamus in never-medicated patients with schizophrenia

OBJECTIVE

This study reports the first paired measurements of glucose metabolism and size of thalamic regions in never-medicated schizophrenic patients using coregistered magnetic resonance imaging (MRI) templates.

METHOD

Positron emission tomography with [18F]fluorodeoxyglucose and matching MRI scans were obtained in 20 never-medicated patients with schizophrenia and 15 normal volunteers. Methods for thalamic edge finding, statistical testing of shape differences with chi-square maps, and MRI localization of major thalamic subregions were developed.

RESULTS

Patients with schizophrenia showed a diminished metabolic rate in the right thalamus, with a loss of the normal pattern of right greater than left asymmetry. Division into anterior/posterior segments revealed that the left anterior and right posterior showed the decrease. Differences were greater for metabolism in the weighted thalamic area (ratexarea) than for rate per unit area, a finding consistent with reported greater decreases in total neuron number than of neuron density in the thalami of schizophrenic patients. The area of the thalamus was smaller in the patients than in the volunteers, and this difference was greatest in the left anterior region.

CONCLUSIONS

The reduced thalamic activity observed in this study lends further support to the concept of deficits in sensory filtering in schizophrenia.

Striatal metabolic rate and clinical response to neuroleptics in schizophrenia

A low metabolic rate in the caudate nucleus and putamen in schizophrenic patients while they were not receiving medication was found to predict a favorable clinical response to haloperidol. Twenty-five patients (21 men and four women) entered a double-blind crossover trial of haloperidol and placebo; to our knowledge, this is the first such trial with positron emission tomography to be reported. Patients received either placebo or medication for the first 5 weeks, and they received the other treatment for the second 5 weeks. Positron emission tomographic scans were obtained at weeks 5 and 10. Patients with low relative metabolic rates in the caudate nucleus and putamen while they were receiving placebo were more likely to show decreases in their Brief Psychiatric Rating Scale scores with haloperidol treatment than individuals with normal or high metabolic rates. Among responders, haloperidol treatment had a "normalizing" effect on metabolic activity in the striatum, with the metabolic rate while they were receiving haloperidol being higher than that while they were receiving placebo. Nonresponders were more likely to show a worsening of hypofrontality while they were receiving medication and an absence of change in the striatum.

[Determination of guanine and cytosine contents of Trichophyton rubrum nuclear DNA with the thermal denaturation technique]

We report here on the G + C mol% content of T. rubrum DNA (including T. rubrum types I-V and an isolate from a patient with tinea pedis) as determined by a thermal denaturation technique. The results are as follows: 45.5, 57.37, 44.22, 45.38, 45.54, and 49.41 mol% for T. rubrum types I-V and isolate respectively. The results are similar to those in the literature, except that the value of T. rubrum type II is slightly higher. Our observations indicate that the morphological heterogeneity of different types of T. rubrum do not seem to be reflected in their G + C mol% values. The authors suggest that the method used here for determining G + C mol% is easy and reproducible.