Plumboporphyria (ALAD deficiency) in a lead worker: a scenario for potential diagnostic confusion

A lead worker developed bilateral wrist drop. At first this seemed to be a lead neuropathy but all his screening tests for blood and urine toxicity had been within the accepted safety limit during employment. Detailed investigation showed that he had plumboporphyria (ALAD deficiency) which had been symptom free until he was exposed to lead. Details of his porphyrin metabolism are presented.

The Royal Marsden Hospital pelvic radiotherapy trial: technical aspects and quality assurance

Planning and quality control procedures are described for a randomised trial designed to measure the effect on normal tissue toxicity of reducing the volume of normal tissue irradiated through the introduction of Beams-Eye-View designed customised blocks. Consideration is given to the accuracy with which blocks can be designed and to the potential application of multi-leaf collimator technology.

Regulation of the ovine intestinal Na+/glucose co-transporter (SGLT1) is dissociated from mRNA abundance

We have investigated the mechanisms of regulation of the Na+/glucose co-transporter (SGLT1) in a ruminant animal, which is an exceptional model system for studying intestinal glucose transport. Pre-ruminant lambs absorb glucose, produced by hydrolysis of the milk sugar lactose, in the intestine via apical SGLT1 and basolateral facilitative glucose transporters (GLUT2). Weaning coincides with the development of the rumen, and consequently the amount of hexoses reaching the small intestine of the ruminant sheep is undetectable. During development, SGLT1 activity and abundance in intestinal brush-border membranes decreased by over 200-fold, and either maintaining lambs on a milk replacer diet or infusing sheep intestine with D-glucose restored co-transporter activity and expression. We have measured ovine intestinal SGLT1 mRNA levels during development, with changes in diet and after direct infusion of D-glucose or methyl alpha-D-glucopyranoside into the intestinal lumen, in order to determine the level of regulation. During development, mRNA levels decreased only 4-fold. Lambs maintained on a milk replacer diet showed no change in mRNA levels relative to age-matched controls. Finally, upon infusion of the intestine of the ruminant sheep with sugars, D-glucose infusion increased SGLT1 mRNA, but only by 2-fold, compared with a 60-90-fold increase in co-transporter number and activity. Since the change in Na(+)-dependent glucose transport activity is correlated with SGLT1 protein abundance, and since changes in mRNA levels do not account for the dramatic changes in protein abundance, we conclude that the principal level of SGLT1 regulation by luminal sugar is translational or post-translational.

The expression of the Na+/glucose cotransporter (SGLT1) gene in lamb small intestine during postnatal development

We have shown previously that the activity and abundance of the intestinal Na+/glucose cotransporter (SGLT1) declines dramatically during the postnatal development of lambs, and that it can be restored in the intestine of ruminant sheep by intra-luminal infusion of D-glucose. The work presented in this paper has followed the expression of the SGLT1 gene along the vertical and horizontal axes of the ovine small intestine during early development, using quantitative in situ hybridisation histochemistry. Along the vertical axis, SGLT1 mRNA was first detectable just below the crypt-villus junction and rose rapidly to a peak level approx. 150 microns above this point. After reaching a maximum, the amount of message gradually declined towards the villus tip. This pattern of mRNA accumulation along the crypt-villus axis was similar in all intestinal positions and age groups. Along the length of the small intestine (horizontal axis), a decline in the level of SGLT1 mRNA was observed first in the distal intestine. This decrease in SGLT1 mRNA was significant in the intestine (75% of length) of 5-week-old lambs when compared to tissue taken from 25 and 50% of length (P < 0.01 and P < 0.02, respectively). However, the observed fall in the expression of this gene during weaning did not coincide with the fall in activity and amount of SGLT1. In adult animals, where the activity of SGLT1 is very low, the amount of message was greatly reduced. This work supports the finding that the expression of SGLT1 is primarily controlled at the post-transcriptional level during the postnatal development of ovine intestine.

Image comparison techniques for use with megavoltage imaging systems

In this paper we describe software facilities for enabling patient positioning studies using the megavoltage imaging system developed at the Royal Marsden Hospital and Institute of Cancer Research. The study focuses on the use of the system for three purposes: patient position verification (by comparing images taken at treatment simulation with megavoltage images taken at treatment time); reproducibility studies (by analysing a set of megavoltage images); and set-up correction (by adjusting the set-up until the megavoltage image obtained at treatment registers with the simulation image). The need is discussed for suitably presented simulator images, a method of determining field boundaries and the possibility of delineating soft-tissue interfaces. Several algorithms of different types, developed specifically for the purpose of intercomparison of planar projection images, are presented. The techniques employed and their usefulness, in both the qualitative and the quantitative sense, are discussed. The results are presented of a phantom and clinical study, to evaluate the rigour and reproducibility of the algorithms. These results indicate that measurements can be made to an accuracy of about 1-2 mm, with a similar value for interobserver reproducibility for the best image comparison techniques available.

Molecular genetics of intestinal glucose transport

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Glucose/galactose malabsorption caused by a defect in the Na+/glucose cotransporter

Glucose/galactose malabsorption (GGM) is an autosomal recessive disease manifesting within the first weeks of life and characterized by a selective failure to absorb dietary glucose and galactose from the intestine. The consequent severe diarrhoea and dehydration are usually fatal unless these sugars are eliminated from the diet. Intestinal biopsies of GGM patients have revealed a specific defect in Na(+)-dependent absorption of glucose in the brush border. Normal glucose absorption is mediated by the Na+/glucose cotransporter in the brush border membrane of the intestinal epithelium. Cellular influx is driven by the transmembrane Na+ electrochemical potential gradient; thereafter the sugar moves to the blood across the basolateral membrane via the facilitated glucose carrier. We have previously cloned and sequenced a Na+/glucose cotransporter from normal human ileum and shown that this gene, SGLT1, resides on the distal q arm of chromosome 22. We have now amplified SGLT1 complementary DNA and genomic DNA from members of a family affected with GGM by the polymerase chain reaction. Sequence analysis of the amplified products has revealed a single missense mutation in SGLT1 which cosegregates with the GGM phenotype and results in a complete loss of Na(+)-dependent glucose transport in Xenopus oocytes injected with this complementary RNA.

National Institute of Mental Health longitudinal study of chronic schizophrenia. Prognosis and predictors of outcome

We performed a longitudinal study of chronic schizophrenic patients who were hospitalized for research purposes at the National Institute of Mental Health (NIMH) Intramural Program in the 1970s and early 1980s. We assessed present course, outcome and predictor data from the initial cohort of 58 young chronic schizophrenic patients who were followed up for 2 to 12 years following their NIMH index hospitalization. At follow-up, the sample showed substantial functional impairment and levels of symptoms with only about 20% of the sample demonstrating a good outcome. In addition, strong intercorrelation was noted among the symptom and functioning indexes at follow-up. Moreover, neuropsychologic tests of frontal cortical functioning were significantly correlated with outcome levels of negative symptoms and social functioning but not with levels of positive symptoms. During the period from the index hospitalization to the follow-up assessment, 78% of the sample suffered a relapse, 38% attempted suicide and 24% had episodes of major affective illness. Furthermore, levels of positive and negative symptoms ascertained when patients received optimal neuroleptic treatment during the index hospitalization significantly predicted outcome levels of symptoms and functioning and time spent hospitalized during the follow-up period. In contrast, levels of index positive and negative symptoms ascertained during the drug-free state did not predict outcome symptoms or functioning. These data suggest that treatment response is a critical predictor variable. We examined the implication of these data for the course of illness in schizophrenics.

Glycyl-L-proline transport in rabbit enterocyte basolateral-membrane vesicles

The properties of a peptide-transport system in rabbit enterocyte basolateral membrane were examined with glycyl-L-proline as the substrate. Basolateral-membrane vesicles prepared from rabbit proximal intestine were characterized in terms of both purity and orientation. Marker-enzyme assays show that the basolateral-membrane marker, ouabain-sensitive K(+)-activated phosphatase, is enriched 17-fold with respect to the initial homogenate. The activities of enzymes used as markers for other membranes and organelles are low, and contamination of the final membrane fraction with these is minimal. The use of immunoblotting techniques further confirms the absence of brush-border-membrane contamination. Proteins in the basolateral-membrane vesicle preparation gave no cross-reaction with antibodies against the 140 kDa antigen and the Na+/glucose-symport protein, markers specific to the brush-border membrane of the enterocyte. Conversely, antibodies raised against the classical basolateral-membrane marker, the RLA class I histocompatibility complex, reacted strongly with a 43 kDa basolateral-membrane protein. The orientation of the basolateral-membrane vesicles was shown to be predominantly inside-out on determination by two independent criteria. The uptake of [1-14C]glycyl-L-proline by these vesicles is stimulated by the presence of an inwardly directed pH gradient, and this stimulation can be abolished by the proton ionophores carbonyl cyanide p-trichloromethoxyphenylhydrazone (CCCP) and tetrachlorotrifluoromethylbenzimidazole (TTFB). Transport is also inhibited by HgCl2, thimerosal, Na+ and other glycyl dipeptides.

Preparation and properties of brush-border membrane vesicles from human small intestine

This study describes a simple and rapid method for the preparation of brush-border membrane vesicles from intestinal biopsies. The specific activities of sucrase, amino peptidase N, and alkaline phosphatase in these vesicles were the same as those in vesicles prepared from intestinal segments. The vesicles from all the regions of the small intestine can transport D-glucose in an Na+-dependent manner. The rates of transport of D-glucose presented here are far higher than previously reported. The method should have a wide applicability to studies of transport mechanisms and the distribution of transport processes within the intestine.

Changes in the functions of the intestinal brush border membrane during the development of the ruminant habit in lambs

1. Brush border membrane vesicles were prepared from lamb enterocytes. These were used to study the changes in the enzyme contents and the transport capacities which occur during the change from a milk to a roughage diet. 2. Na+-dependent transport of D-glucose was present in all regions of the small intestine of pre-ruminant lambs and absent in ruminants. 3. Na+-dependent transport of L-proline was present in all regions of the small intestine irrespective of the age of the animal. 4. Phosphate transport was seen only in the presence of a transmembrane pH gradient (acid outside). The transport was not stimulated by either Na+ or K+. The transport capacity increases 2-fold as the animal becomes ruminant. 5. The activities of lactase and maltase diminished with age. Alkaline phosphatase and aminopeptidase N activities remain constant. Sucrase activity cannot be detected in lambs of any age.

IgE-immunotoxins. I. IgE-intact ricin

An IgE immunotoxin consisting of rat IgE myeloma protein, IR 162, conjugated via the heterobifunctional linking agent N-succinimidyl-3-(2-pyridyldithio)propionate to intact ricin was synthesized and evaluated. The capacity of this IgE-immunotoxin to bind to rat basophilic leukemia cells (RBL cells) and to inhibit RBL cell incorporation of [3H]leucine was assessed. The IgE-intact ricin conjugate sensitized RBL cells for histamine release after treatment with anti-IgE with a time-course of sensitization and dose-response equivalent to native IgE. Intact ricin and IgE-intact ricin were both cytotoxic to RBL cells as assessed by [3H]leucine incorporation. Lactose (50 mM) competed with intact ricin binding and toxicity such that more than 100 ng/ml ricin (8 times its IC50 in the absence of lactose) was required for ricin to kill RBL cells in the presence of lactose. Lactose (50 mM) was not able to fully inhibit 1-100 ng/ml IgE-ricin immunotoxin killing of RBL cells. Saturation of RBL cell IgE receptors by preincubation with IgE totally inhibited IgE-intact ricin-induced toxicity, in the presence of lactose, indicating that toxicity required IgE Fc receptor binding.

Cooperation not confrontation: the imperative of a nuclear age

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Cavernous haemangioma of the orbit

Cavernous haemangioma is considered the most common primary orbital tumour. We present three cases of cavernous haemangioma of the orbit presenting with deterioration of vision and painless unilateral exophthalmos. A review of the current literature available is compared with our findings. The diagnostic examinations that are most helpful in deciding that an orbital cavernous haemangioma is present include plain film X-ray examination of the orbits and sinuses, B-mode ultrasonography and computerized axial tomography. Each patient underwent a transcranial surgical procedure for removal of the tumour, after pre-operative evaluation.

Increased antigen-induced local and systemic mediator release in rhinitis subjects with pulmonary symptoms in the pollen season

In order to delineate parameters that might discriminate between allergic subjects who develop R or R-P symptoms during natural antigen exposure, 26 subjects allergic to grass or ragweed pollen were classified into R or R-P groups, and then the antigen sensitivity and degree of in vivo mediator release were compared. Antigen-skin sensitivity was quantitated by dilutional skin-test titration, and bronchial sensitivity was quantitated by the amount of inhaled antigen required to receive the FEV1 by 20%. Mediator release was determined by measuring the amount of histamine that was released into skin chambers during antigen incubation and the rise in plasma histamine and serum NCA during antigen-induced bronchospasm. Compared to the 13 R subjects, the 13 R-P subjects were: (1) more sensitive to antigen by both skin-test and inhalation challenge, (2) responded to inhalation of antigen with a greater fall in FEV1 and a greater rise in serum NCA and plasma histamine, and (3) released more histamine into skin chambers after antigen incubation. Even when R and R-P subjects were matched by comparing only subjects with equal skin sensitivity to antigen, greater increases in serum NCA and plasma histamine occurred after inhalation of antigen in the R-P subjects. These data are consistent with the hypothesis that allergic rhinitis subjects who develop pulmonary symptoms during natural pollen exposure are more sensitive to antigen and release more mediators in response to antigen administration. It is therefore possible that the degree of mediator release may be an important factor in determining the pattern of clinical responses to antigen exposure.

Increased urine histamine and contrast media reactions

Urine samples were collected from 200 subjects undergoing intravenous pyelography. The urine histamine levels were compared with those of 132 normal control subjects, 11 subjects with systemic mastocytosis, six subjects with idiopathic anaphylaxis, and ten subjects experiencing mild anaphylactic reactions during allergy immunotherapy. Compared with normal controls, as a group, all subjects receiving intravenous contrast media had increased urine histamine (P less than 0.05 by Student's t-test) while those subjects experiencing adverse reactions had considerably larger increases. The urine histamine levels in the subjects experiencing systemic reactions were in the same range as those observed in patients having mild anaphylactic reactions to immunotherapy and somewhat lower than those found in idiopathic anaphylaxis or systemic mastocytosis. These data suggest that some histamine release accompanies infusions of contrast media in all subjects and that larger amounts of histamine release are associated with adverse reactions.

Measurement of urinary histamine: comparison of fluorometric and radioisotopic-enzymatic assay procedures

Assessment of urinary histamine may prove useful in determining the role of histamine in human health and disease. Urinary histamine may be accurately estimated by a modified fluorometric assay employing diamine oxidase (DAO) digestion and cation-exchange chromatography. Normal urine histamine values obtained by this assay are: arithmetic means (+/- SEM), 8.6 +/- 0.6 ng/ml and 10.5 +/- 0.7 micrograms/24 hr; geometric means (+/- SEM), 6.2 +/- 1.1 ng/ml and 10.0 +/- 1.3 micrograms/24 hr. However, the radioisotopic-enzymatic assay is less expensive, easier to perform, and possibly more sensitive. Therefore the two procedures were compared. The radioenzyme assay was found to be affected by factors in urine (possibly salt concentrations) requiring extraction of histamine from urine by butanol-heptane. Moreover, it was found to be necessary to compare DAO-digested samples with undigested samples to accurately estimate histamine levels and to run the standard curve of histamine in DAO-digested urine. Even with these modifications, the radioenzyme assay was not as accurate as the fluorometric assay for urine samples having histamine values about 60 ng/ml. Therefore we recommend utilization of the modified fluorometric assay for the measurement of urinary histamine levels.

Direct action of D-lysergic acid diethylamide on dispersed mucosal cells from guinea pig stomach

In dispersed mucosal cells from guinea pig stomach, D-lysergic acid diethylamide (LSD) was a partial agonist with respect to histamine. LSD, like histamine, inhibited [3H]histamine binding and increased both cellular cyclic AMP and [14C]aminopyrine uptake by interacting with histamine H2-receptors on parietal cells. These processes were blocked by both histamine H1- and H2-antagonists and, thus, provide evidence that histamine H2-receptors on guinea pig parietal cells resemble those in brain tissue in that they interact with LSD as well as with both classes of histamine antagonists.

Measurement of plasma histamine: description of an improved method and normal values

The single isotopic-enzymatic assay of histamine was modified to increase its sensitivity and to facilitate measurement of plasma histamine levels. The modification involved extracting 3H-1-methylhistamine (generated by the enzyme N-methyltransferase acting on histamine in the presence of S-[methyl-3H]-adenosyl-L-methionine) into chloroform and isolating the 3H-1-methylhistamine by thin-layer chromatography (TLC). The TLC was developed in acetone:ammonium hydroxide (95:10), and the methylhistamine spot (Rf = 0.50) was identified with an o-phthalaldehyde spray, scraped from the plate, and assayed in a scintillation counter. The assay in plasma demonstrated a linear relationship from 200 to 5000 pg histamine/ml. Plasma always had higher readings than buffer, and dialysis of plasma returned these values to the same level as buffer, suggesting that the baseline elevations might be attributable to histamine. However, all histamine standard curves were run in dialyzed plasma to negate any additional influences plasma might exert on the assay. The arithmetic mean (+/- SEM) in normal plasma histamine was 318.4 +/- 25 pg/ml (n = 51), and the geometric mean was 280 +/- 35 pg/ml. Plasma histamine was significantly elevated by infusion of histamine at 0.05 to 1.0 micrograms/kg/min or by cold immersion of the hand of a cold-urticaria patient. Therefore this modified isotopic-enzymatic assay of histamine is extremely sensitive, capable of measuring fluctuations in plasma histamine levels within the normal range, and potentially useful in analysis of the role histamine plays in human physiology.

Aminopyrine uptake by guinea pig gastric mucosal cells. Mediation by cyclic AMP and interactions among secretagogues

The role of cyclic nucleotides in regulating acid secretion by dispersed mucosal cells from guinea-pig stomach was examined by measuring first the ability of histamine and carbachol to stimulate [dimethylamine-14C]aminopyrine uptake and cyclic nucleotide metabolism and secondly, the effect of exogenous cyclic nucleotides on basal and stimulated [14C]aminopyrine uptake. The [14C]aminopyrine was found in an acidic, osmotically sensitive compartment, probably associated with the initial steps in acid secretion by these cells. Although histamine increased [14C]aminopyrine uptake and cyclic AMP synthesis as expected, histamine was approx. 10-fold more potent in inducing [14C]aminopyrine uptake. This dissociation of [14C]aminopyrine uptake and cyclic AMP metabolism process was further manifested by the observation that prostaglandin E1 failed to increase [14C]aminopyrine uptake, although it did cause a rise in cellular cyclic AMP. Furthermore, prostaglandin E1 did not alter the [14C]-aminopyrine uptake caused by histamine. Carbachol was found to increase the [14C]aminopyrine uptake and also to potentiate the ability of histamine to increase [14C]aminopyrine uptake. Carbachol, however, affected neither the histamine-induced increase in cyclic AMP nor the binding of [3H]histamine to the cells. Cimetidine, a histamine H2 receptor antagonist, blocked the [14C]aminopyrine uptake induced either by histamine alone or by the potentiating combination of histamine plus carbachol. These results suggest that cyclic AMP is mediating the action of histamine on [14C]aminopyrine uptake but changes in cyclic AMP per se are not necessarily the cause for the potentiated increase in [14C]aminopyrine uptake. Furthermore, the potentiated response observed with histamine plus carbachol on [14C]aminopyrine uptake occurs at a biochemical step distal to and not obviously related to cyclic AMP generation.