The neuropathology of schizophrenia: A selective review of past studies and emerging themes in brain structure and cytoarchitecture.

Schizophrenia is a devastating mental illness. Although its etiology is still largely unknown, strides have been taken throughout the last several decades to elucidate the nature of the neuropathology behind this disorder. The advent of neuroimaging technologies such as computerized axial tomography and magnetic resonance imaging have progressed knowledge about the macroscopic brain changes that occur in schizophrenia, including the characteristic enlarged ventricle size and reductions in gray matter volume, whole-brain volume, and white matter anisotropy. Although this review presents a broad outline of current and historical neuropathological research, the focus is primarily on the quantitative neuropathology of the cerebral cortex in schizophrenia, which may underlie many of the larger scale changes observed. The reduced neuropil hypothesis has been suggested as a microanatomical explanation to account for these macroscopic changes, although the present review finds that evidence does not always support this. A quantitative meta-analytic summary of these studies, focused on neuron density, provides support for the finding of increased neuron density in schizophrenia, with variation dependent on age. This is consistent with neuroimaging data and implicates an altered aging trajectory as a factor in the pathogenesis of schizophrenia. Combined with evidence from other neuroanatomical studies reviewed here, as well as studies in childhood-onset schizophrenia, the evidence converges on a progressive neurodevelopmental model of schizophrenia related to altered neuroplasticity. The evidence also supports a particular vulnerability of inhibitory cortical circuits with markers of interneurons showing some of the more consistent reductions in schizophrenia.

Randomized placebo-controlled trial of the activity of the morphine glucuronides.

BACKGROUND: Morphine-6-glucuronide (M6G) is an active metabolite of morphine with potent analgesic activity. Morphine-3-glucuronide (M3G), the most prevalent metabolite, has minimal affinity for opioid receptors. It has been suggested from animal model data and by examination of metabolite ratios in humans that M3G may functionally antagonize the respiratory depressant and analgesic actions of morphine and M6G. METHODS: We performed a double-blind placebo-controlled trial with 10 healthy volunteers. The trial had 6 arms: (1) placebo, (2) 10 mg/70 kg of morphine, (3) 3.3 mg/70 kg of M6G, (4) 30.6 mg/70 kg of M3G, (5) 30.6 mg/70 kg of M3G with 10 mg/70 kg of morphine, and (6) 30.6 mg/70 kg of M3G with 3.3 mg/70 kg of M6G; all were give by slow intravenous bolus. Analgesia was assessed with the use of the submaximal ischemic pain model. The effects were quantified on numerical and visual analogue scales. Respiratory parameters and response to steady state 5% carbon dioxide challenge were assessed with spirometry, mass spectroscopy, and earlobe blood gas analysis. RESULTS: Morphine and M6G produced significant pain relief compared with placebo (morphine, P < .0001; M6G, P = .033). Pain relief after M6G was less than after morphine (P = .009) and M3G was no better than placebo (P = .26). Pain relief with morphine and M6G were not significantly altered by M3G (P = .59 and P = .28, respectively). Significant and similar dysphoria and sedation occurred with both morphine (P < .002) and M6G (P < .016) but were absent with both M3G and placebo. Respiratory parameters suggested that M6G produced less respiratory depression than morphine. Both morphine and M6G caused a significant reduction in respiratory drive compared with placebo (morphine, P = .002; M6G, P = .013); this effect was not reversed by M3G (P = .35 and P = .83, respectively). CONCLUSIONS: M3G appears to be devoid of significant activity; in these circumstances and at these doses, it does not antagonize either the analgesic or respiratory depressant effects of M6G or morphine.

Adenoid histamine and its possible relationship to secretory otitis media.

We have shown that adenoid tissue contains large amounts of the inflammatory mediator histamine. Children with fluid present in both ears at operation were found to have increased amounts of histamine in their adenoid tissue compared to a group with no signs or symptoms of SOM. Also mouth breathing and nasal obstruction were associated with adenoid histamine content whereas other signs and symptoms were not. No significant differences in adenoid weight were seen between SOM and non SOM patients. Histamine, both free and cell-associated, was found in nasopharyngeal secretions and middle-ear fluid although the source and mechanism of release has not yet been identified. We suggest that the benefits of adenoidectomy in children with SOM may possibly come from removing a potential source of inflammatory mediators in the vicinity of the Eustachian tube.

Histamine and secretory otitis media.

Histamine, both free and cell associated, has been demonstrated in middle ear fluid from patients with secretory otitis media (SOM). Histamine, mainly free in solution, has also been shown to be present in nasopharyngeal secretions taken from close to the Eustachian tube openings into the nasopharynx. The adenoids from patients with middle ear effusion contained significantly (P less than 0.05) more histamine than those with no effusion. However, in preliminary experiments, we could demonstrate no differences in the histamine secretory response of adenoids from SOM and non-SOM patients to anti-immunoglobulin E (anti-IgE), house dust mite antigen and calcium inophore A23187 in vitro. These results support the hypothesis of an inflammatory basis for SOM.