Gamma-glutamyl transpeptidase in brain capillaries: possible site of a blood-brain barrier for amino acids.

A fraction containing capillaries and rich in gamma-glutamyl transpeptidase was isolated from homogenates of bovine brain cortex by density gradient centrifugation. The enzyme was localized in the endothelial cells by a histochemical procedure. gamma-Glutantyl transpeptidase may function in the transfer of some amino acids across the blood-brain barrier.

Acetylcholine: release from neural tissue and identification by pyrolysis--gas chromatography.

Gas chromatographic analysis showed acetylcholine to be the only choline ester released from innervated longitudinal muscle of the guinea pigileum by electrical stimulation. The amount of acetylcholine measured by gas chromatography agreed almost exactly with that measured by bioassay. Denervated longitudinal muscle produced no acetylcholine, and treatment of the muscle with tetrodotoxin markedly reduced acetylcholine output. The method permits the recovery and quantitation of amounts of acetylcholine as low as 5 nanograms in 5 milliliters of tissue perfusates.

Studies on histamine H2 receptors coupled to cardiac adenylate cyclase. Effects of guanylnucleotides and structural requirements for agonist activity.

In particulate preparations from guinea-pig ventricle, histamine in the concentration range 10(-6)--10(-3) M caused a 3--5fold stimulation of adenylate cyclase activity which was dependent on the presence of GTP. The effects of fourteen analogs of histamine were examined on this cyclase preparation. Five of the compounds studied proved to be partial agonists relative to histamine while nine others had essentially the same intrinsic activity as histamine. The intrinsic activities of the partial agonists were increased by GppNHp to the extent that dimaprit, which was a partial agonist in the presence of GTP, became a full agonist in the presence of GppNHp. The relative potencies of the full agonists as activators of the cyclase were found to correlate with the relative potencies on physiologically defined H2 receptor systems. Activation of the cyclase by histamine, as well as by several of the agonist analogs, including dimaprit and tolazoline, was completely blocked by the H2 antagonist cimetidine, but was not affected by pharmacologically relevant concentrations of the H1 antagonist mepyramine, the beta-blocker alprenolol, or the alpha-blocker phentolamine. The results suggest that all the agonists studied probably interact with a common H2 receptor site on the cardiac muscle cell leading to activation of adenylate cyclase. The accompanying increase in cyclic AMP is presumably responsible for the chronotropic and inotropic effects of histamine and related compounds on cardiac muscle.

The structure, physical and chemical properties of the soy bean protein glycinin.

The major storage protein of the soybean, glycinin, has been prepared in a homogeneous form and examined by a variety of techniques. It has been found that the protein has a molecular weight of 320000 and contains two sizes of subunits with different isoelectric points. There are six acidic subunits of approximately 35000 and six basic of approximately 20000. Analysis revealed three different kinds of acidic subunits and probably three kinds of basic ones also. These twelve subunits are packed in two identical hexagons, placed one on the other, yielding a hollow oblate cylinder of 110 X 110 X 75 A. Some or all of the subunits are non-spherical resulting in a partial blocking of the central hole. Information about the forces stabilzing the native structure is also discussed.

Pharmacological receptors: the need for a compendium of classification, nomenclature and structure.

In an attempt to contain the chaos of receptor nomenclature, the supplement distributed with this issue of TiPS catalogues cell surface receptors and their subtypes according to the most commonly used nomenclature and describes them in pharmacological, biochemical and molecular terms. This reporting of the status quo will be an invaluable aid to communication, but all scientists (not just pharmacologists) working on receptors would agree that a radical and rational classification of receptors also needs to be initiated. In this article, Jack Peter Green proposes a system of (and mechanism for) classification that should satisfy both the 'taxonomic realists' and the 'taxonomic skeptics'.

Efficacy of radiation therapy alone for limited squamous cell carcinoma of the anal canal.

From 1973-1986, thirty-five patients with limited squamous cell carcinoma of the anal canal underwent definitive radiation therapy only. There were twenty females and fifteen males with average ages of 65 and 53 years, respectively. Twelve of the fifteen males were admittedly homosexual. The primary lesions were less than 5 cm in maximum dimension and were confined to the anal canal. Two patients presented with regional adenopathy. Chemotherapy was not used in any case. Treatment plans were individualized but usually included whole pelvis and boost external beam irradiation. The average tumor dose was 6395 cGy (range 4525-7550 cGy). One interstitial Ir-192 implant was performed. Local control was 77% (27/35) following radiation therapy alone. Seven of the eight failures were salvaged surgically, five by abdominoperineal resection and two by local excision, for an overall rate of 97% (34/35). The 5-year actuarial disease-free survival is 92%. Only two patients have disseminated and/or died of neoplasm. Anal continence was retained in 80% (28/35). Early and late complication rates were acceptable.

Primary radiation therapy in the treatment of anal carcinoma.

From 1966 to 1981, 47 patients with a diagnosis of anal carcinoma were irradiated. This group was composed of 23 males and 24 females, with age ranging from 38-84 years (average 64.4 years). The average age of the males was eight years less than the females. Of the 47 patients, 39 had an intact anal canal following biopsy and were treated with curative intent. Thirty-one of these 39 had no evidence of nodal metastasis (N0) and eight had groin, pelvic and/or para-aortic nodal disease. Only three patients were treated with pre-irradiation chemotherapy; all had locally advanced disease. Five patients were treated preoperatively and 34 were treated definitively with cancericidal doses of irradiation. Acute radiation reactions requiring a rest-break were noted in 28% of patients, but all were managed as outpatients without untoward chronic sequelae. Chronic complications were noted in 13 patients, including two patients who required colostomy for severe anal stenosis and two who required A-P resection for large painful ulcers. Two of these four patients had received part of their treatment with an interstitial implant and one had an excessively high dose of perineal irradiation. Twenty-eight of 35 patients (80%) treated with irradiation alone have remained locally controlled without further treatment. An additional four have been salvaged by surgery. Only three patients had interstitial implants as part of their treatment course. Actuarial survival at five years for the N0 patients and the group as a whole are 95.6 and 79.3%, respectively. It is concluded that external beam irradiation alone, properly fractionated to cancericidal doses, can control anal carcinoma with acceptable morbidity rates and without the use of either chemotherapy or interstitial implants in most cases. There is also a strong correlation suggesting that anal intercourse and male homosexuality play a significant role in the etiology of this disease.

Prostatic carcinoma: limited field irradiation.

This is a retrospective study of 251 patients with histologically proven adenocarcinoma treated primarily with limited field radiotherapy techniques, under the principle direction of authors JMV and JPG, between 1968 and 1981 in San Francisco, California. All patients are followed for a minimum of 3 years; mean follow-up is 7.3 years. Routine clinical staging procedures included: H&P, digital prostate exam, cystoscopy, biopsy, blood studies including serum acid phosphatase, and imaging studies including chest X ray, IVP, bone survey or radionucleotide bone scan, and in recent years, pelvic CT scans. Twelve patients are Stage A1, 37-Stage A2, 50-Stage B, 140-Stage C1 and 12-Stage C2. Ninety percent of all cases and 85% of Stage C patients were treated with limited fields to the prostate and periprostatic volume only. Total doses were prescribed at midplane or isocenter and were generally 6500-7000 cGy, daily doses of 180-200 cGy, 5 days per week. Actuarial 5- and 10-year survival rates are: entire population-69% and 47%; Stage A1-74% and 50%; Stage A2-81% and 67%; Stage B-84% and 53%; Stage C1-63% and 42%; Stage C2-32% and 11%. The 5- and 10-year disease-free actuarial survivals are: entire population-71% and 50%; Stage A1-89% and 74%; Stage A2-82% and 69%; Stage B-71% and 52%; Stage C1-67% and 44%; Stage C2-0%. Sites of recurrence, alone or as a component of the failure pattern are: 37 (15%) local, 11 (4%) symptomatic regional recurrence (lower extremity edema, pelvic pain/sciatica, hydroureteronephrosis), and 87 (35%) distant metastasis. Seven (3%) had unknown sites of failure. Local-regional failure occurred in 42% of Stage C2 patients. Concomitant hormonal therapy has no survival impact on Stage C1 patients and poorly differentiated histology is associated with decreased determinate and disease-free survival rate of 5 years. Complications correlate with treatment technique, being more frequent with single field per day treatment plans. In patients treated with multiple fields per day or rotational plans, complications occur in less than 8% of patients and major complications have not occurred.

The influence of field size, treatment modality, commissure involvement and histology in the treatment of early vocal cord cancer with irradiation.

One hundred and thirty-seven patients with TNM staged T1 glottic cancer were treated from 1966 to 1980. The patient characteristics were no different from those noted in previous studies. Patients were treated either with 60Co teletherapy units or 4 MeV linear accelerators with different daily (180-225) and weekly (4 times vs. 5 times) fractionation schemes. A recurrent-free survival was attained in 80% of the patients 2 years after primary treatment with radiation therapy. There were 27 local recurrences, of which 82% were salvaged with surgery for an overall adjusted survival of 95%. Patients treated on 60Co units with field sizes less than or equal to 30 sq. cm had a 15% increase in local recurrence compared with field size greater than 30 sq. cm, which could not be attributed to lower doses. Poorly differentiated tumors and those involving the anterior commissure were more likely to develop a local recurrence. Doses above 1900 ret were associated with a decrease in local recurrence in patients having anterior commissure involvement. Salvage with limited surgery for failure was effective in selected cases.

Acetylcholine metabolism in the rat hippocampus and striatum following one-trial passive training.

The steady state levels of acetylcholine and choline and the synthesis of acetylcholine in the hippocampus and striatum of rat brain have been determined after one-trial passive avoidance training. Steady state levels of acetylcholine and choline were not altered, but the rate of acetylcholine synthesis was significantly elevated in the striatum but not significantly elevated in the hippocampus at one hour after training.

Thyroid uptake of 131I: further comparisons of capsules and liquid preparations.

Comparisons were made of thyroid uptake of three commercially available preparations of 131I, using a double-blind design, in 125 patients with normal thyroid function. Uptakes with Squibb Iodotope Diagnostic capsules were significantly lower than those with Squibb Iodotope Oral liquid at 4 hr (p less than 0.01) and 24 hr (p less than 0.05) after ingestion in both the general population and in all patients less than 45 years of age. Uptakes of Radiocaps I-131 (Abbott Laboratories) and Iodotope Oral liquid were indistinguishable under identical conditions. Our findings indicate that interference with either absorption or metabolism of a pharmaceutical can result from the vehicle used to administer it.

Functional evaluation of a hepatic scintigraphic defect using ultrasound and a fatty meal: case report.

Hepatic focal defects identified with 99mTc-sulfur colloid imaging procedures are nonspecific. This report describes a prominent scintigraphic defect shown to be a normally functioning gallbladder.

Effects of pargyline on tele-methylhistamine and histamine in rat brain.

Rapid and complete inhibition of brain MAO produced linear increases in brain t-MH levels from 30 min to 4 hr after drug treatment at a rate of 0.26 nmole/g X hr, resulting in a 3-fold increase which persisted for at least 12 hr. HA levels were slightly elevated 1 and 2 hr after drug administration but quickly returned to control levels, suggestive of sensitive regulatory mechanisms in brain. Although the slight change in HA levels precludes steady-state assumptions, the rate of increase in brain t-MH levels after MAO inhibition provides a novel estimate of the half-life of endogenous brain HA (50 min). Despite the transient effect of pargyline on brain HA content, the effect of pargyline on brain t-MH levels suggests that MAO inhibitors may produce long-term alterations in brain histaminergic dynamics.

Inhibition of brain histamine metabolism by metoprine.

To study the extent to which histamine methylation accounts for the biosynthesis of histamine metabolites in brain, the effects of the histamine methyltransferase (HMT) inhibitor metoprine were determined on the whole brain levels of tele-methylhistamine (t-MH), its oxidative metabolite tele-methylimidazoleacetic acid (t-MIAA), and brain HMT activity in albino rats. Metoprine (5-30 mg/kg) reduced brain t-MH levels by about 75% and caused a dose-dependent reduction (70-90%) in HMT activity 4 hr after administration. Furthermore, the levels of t-MH remaining in each brain after metoprine treatment were significantly positively correlated with the remaining HMT activity of that brain after all doses of drug. Although brain t-MIAA levels were reduced by only 30% 4 hr after metoprine administration, the levels were reduced by about 75% 12 hr after the drug, similar to the reduction in t-MH levels. These findings support previous suggestions that t-MH and t-MIAA in brain arise from brain histamine metabolism, and that brain t-MH synthesis is equivalent to histamine methylation.

Paralysis of downgaze in two patients with clinical-radiologic correlation.

Selective downgaze paralysis was correlated with discrete bilateral lesions at the mesencephalic-diencephalic junction in a 9-year-old girl following severe pneumococcal meningitis, and in a 64-year-old man who suffered an embolic infarction. Magnetic resonance imaging demonstrated bilateral lesions in the region of the rostral interstitial nucleus of the medial longitudinal fasciculus. Clinical-radiologic correlation allowed identification of the likely vascular cause in both patients.

Histamine metabolites in cerebrospinal fluid of patients with chronic schizophrenia: their relationships to levels of other aminergic transmitters and ratings of symptoms.

Levels of the histamine metabolites, tele-methylhistamine (t-MH) and tele-methylimidazoleacetic acid (t-MIAA), and metabolites of other aminergic transmitters and of norepinephrine were measured in cerebrospinal fluid of 36 inpatients with chronic schizophrenia and eight controls. The mean t-MH level from controls was nearly identical to the levels seen previously in healthy volunteers. Compared with controls, the mean level of t-MH in the schizophrenic patients was 2.6-fold higher (p = 0.006); 21 of the patients had levels exceeding the range of controls. There was no significant difference (p > 0.05) in levels of other analytes, although the levels of t-MH correlated significantly with those of t-MIAA, homovanillic acid, 3,4-dihydroxyphenylacetic acid, norepinephrine, 3-methoxy-4-hydroxyphenylglycol and 5-hydroxyindoleacetic acid. The difference in levels of t-MH were not attributable to medication, since those taking (n = 10) or withdrawn from (n = 26) neuroleptic drugs had nearly the same mean levels of t-MH; each group had higher levels than controls (ANOVA: p < 0.05). Patients with or without tardive dyskinesia showed no significant differences in means of any analyte. Only levels of t-MH among those with schizophrenia correlated with positive symptom scores on the Psychiatric Symptom Assessment Scale (rs = 0.45, p < 0.02). The elevated levels of t-MH in cerebrospinal fluid, which represent histamine that was released and metabolized, suggest increased central histaminergic activity in patients with chronic schizophrenia.

The relationship between urine excretion and biogenic amines and their metabolites in cerebrospinal fluid of schizophrenic patients.

Concentrations of norepinephrine and metabolites of biogenic amines were measured in lumbar cerebrospinal fluid of 30 patients with chronic schizophrenia, nine of whom were polyuric. The mean level of norepinephrine was two-fold higher (p < or = 0.025) in polyuric patients than in patients whose excretion of urine was within the normal range. CSF levels of histamine's primary metabolite, tele-methylhistamine, an index of brain histaminergic activity, were positively correlated (p < 0.005) with daily urine volume. These results are consistent with the known influence of norepinephrine and histamine on fluid regulation and suggest that norepinephrine and histamine may be involved in psychogenic polydipsia-polyuria in schizophrenic patients.

Histamine-activated adenylate cyclase in brain homogenates of several species.

Histamine has been shown to activate cyclic AMP synthesis in brain slices and homogenates of certain species, although less is known about species differences in brain homogenates. Dutch Belted and New Zealand White rabbit brain homogenates contained a histamine-responsive adenylate cyclase similar to that of the guinea pig. In contrast, adenylate cyclase of gerbil and hamster brain exhibited little or no stimulation by histamine. Male rat hypothalamic homogenates contained adenylate cyclase, but also exhibited minimal stimulation by histamine, in disagreement with some recent reports. Detailed studies of the conditions of assay failed to resolve this discrepancy.

Regional differences in binding of [3H]LSD and [3H]5-HT in calf hippocampal slices revealed by radioautography and rapid filtration studies.

Previous radioautographic experiments demonstrated that binding sites labeled by [3H]5-HT and [3H]LSD in rat brain were seen in all layers of CA1, CA4 and the dentate gyrus but not in fields CA2 and CA3 of the hippocampus. In an attempt to confirm this observation we performed binding assays on homogenates from selected areas of calf hippocampus since the small size of the rat hippocampus precluded using preparations from this animal for this purpose. Studies on homogenates from calf hippocampal regions, were done after we determined that the binding to slices in vitro was similar in the calf and rat. Binding of both [3H]5-HT and [3H]LSD by homogenates of CA1 and dentate gyrus, but not of CA3, was saturable. These studies show that the qualitative differences in binding site distribution within the calf hippocampus seen by radioautography reflect quantitative differences in the densities of binding sites revealed by the homogenate studies.

Histamine turnover in regions of rat brain.

Rapid and complete inhibition of monoamine oxidase by pargyline produced linear increases in the content of the histamine metabolite, tele-methylhistamine (t-MH), in 9 regions of rat brain 2 and 4 h after drug administration. The treatment had little or no effect on the histamine content of these regions. As histamine methylation is the major metabolic pathway of histamine in brain, the rate of increase in brain t-MH content after complete inhibition of its metabolism provides an estimate of histamine turnover. Histamine turnover rates varied over 46-fold among regions, from cerebellum (0.029 nmol/g . h) to hypothalamus (1.33 nmol/g . h), similar to those reported for norepinephrine and serotonin. Turnover rates were highly correlated with control t-MH levels (r = 0.97) and control histamine levels (r = 0.84). Rate constants were highest in the caudate nucleus and frontal cortex, equivalent to a half-life of about 11 min in these regions. While hypothalamic histamine had the highest turnover rate, the rate constant for histamine in this region was among the lowest in brain, perhaps consistent with the presence of histaminergic cell bodies. Histamine turnover rates may be indicative of the activity of histamine-synthesizing neurons, and their determination will facilitate understanding of histamine in brain.