Part II: Strain- and sex-specific effects of adolescent exposure to THC on adult brain and behaviour: Variants of learning, anxiety and volumetric estimates

Marijuana is one of the most highly used psychoactive substances in the world, and its use typically begins during adolescence, a period of substantial brain development. Females across species appear to be more susceptible to the long-term consequences of marijuana use. Despite the identification of inherent differences between rat strains including measures of anatomy, genetics and behaviour, no studies to our knowledge have examined the long-term consequences of adolescent exposure to marijuana or its main psychoactive component, Δ(9)-tetrahydrocannabinol (THC), in males and females of two widely used rat strains: Long-Evans hooded (LER) and Wistar (WR) rats. THC was administered for 14 consecutive days following puberty onset, and once they reached adulthood, changes in behaviour and in the volume of associated brain areas were quantified. Rats were assessed in behavioural tests of motor, spatial and contextual learning, and anxiety. Some tasks showed effects of injection, since handled and vehicle groups were included as controls. Performance on all tasks, except motor learning, and the volume of associated brain areas were altered with injection or THC administration, although these effects varied by strain and sex group. Finally, analysis revealed treatment-specific correlations between performance and brain volumes. This study is the first of its kind to directly compare males and females of two rat strains for the long-term consequences of adolescent THC exposure. It highlights the importance of considering strain and identifies certain rat strains as susceptible or resilient to the effects of THC.

Glycogen synthase kinase 3β and activin/nodal inhibition in human embryonic stem cells induces a pre-neuroepithelial state that is required for specification to a floor plate cell lineage

The floor plate is one of the major organizers of the developing nervous system through its secretion of sonic hedgehog (Shh). Although the floor plate is located within the neural tube, the derivation of the floor plate during development is still debatable and some studies suggest that floor plate cells are specified by Shh in a temporarily restricted window different to neuroepithelial cells. Using human embryonic stem cells (hESC) as a model of neurogenesis, we sought to determine how floor plate cells may be temporarily specified by SHH signaling during human embryogenesis. We found that inhibition of both GSK3β and activin/nodal pathways in hESC induces a cellular state of SOX2+/PAX6− expression, we describe as “pre-neuroepithelial.” Exposure of SHH during this pre-neuroepithelial period causes the expression of GLI transcription factors to function as activators and consequently upregulate expression of the floor plate marker, FOXA2, while also supressing PAX6 expression to inhibit neuroepithelial fate. FOXA2+ cells were able to efficiently generate mesencephalic dopaminergic neurons, a floor plate derivative. Overall, this study demonstrates a highly efficient system for generating floor plate cells from hESC and, most importantly, reveals that specification of floor plate cells is temporally dependent, whereby it occurs prior to the onset of PAX6 expression, within a pre-neuroepithelial stage. Stem Cells2012;30:2400–2411

Effects on the human central nervous system of two isomers of ephedrine and triprolidine, and their interaction

1 D(-)ephedrine is four times as potent as L(+)pseudoephedrine in producing both tachycardia and a rise in systolic blood pressure. No changes in diastolic blood pressure occurred in 12 subjects with doses of up to D(-)ephedrine (50 mg) and L(+)pseudoephedrine (180 mg). 2 Significant evidence of stimulation of the central nervous system occurred only after D(-)ephedrine in that tapping rates were increased and subjects could reliably detect that they had received an active drug. While mean performance rates in an auditory vigilance test were higher following both ephedrine isomers these changes were not significant. 3 Impairment of both tapping rates and auditory vigilance occurred following triprolidine in another group of 12 subjects. The effect was generally related to dose of antihistamine given and lasted up to 7.25 hours. Subjective effects were reliably recognized by subjects following all treatments containing triprolidine (2.5 mg or more) for up to 4.75 hours. Using analogue lines for self rating the subjective effects following triprolidine indicated both mental and physical impairment differing significantly from scores after lactose and L(+)pseudoephedrine (60 mg). 4 Combination of triprolidine (2.5 mg) and L(+)pseudoephedrine (60 mg) produced effects similar to triprolidine alone on both subjective measures and the auditory vigilance test. It is suggested that these objective tests and subjective scales could be used to measure effects on the central nervous system produced by antihistamines together with similar drugs, and their interaction with other compounds administered concurrently.

N2O emissions: modeling the effect of process configuration and diurnal loading patterns

The objective of this research was to develop a mechanistic model for quantifying N2O emissions from activated sludge plants and demonstrate how this may be used to evaluate the effects of process configuration and diurnal loading patterns. The model describes the mechanistic link between the factors recognized to correlate positively with N2O emissions. The primary factors are the presence of ammonia and nitrite accumulation. Low dissolved oxygen concentrations also may be implicated through differential impacts on ammonia-oxidizing bacteria (AOB) versus nitrite-oxidizing bacteria (NOB) activity. Factors promoting N2O emissions at treatment plants are discussed below. The model was applied to data from laboratory and pilot-scale systems. From a practical standpoint, plant configuration (e.g., plug-flow versus complete-mix), influent loading patterns (and peak load), and certain operating strategies (e.g., handling of return streams) are all important in determining N2O emissions.

Gene expression in HIV-1/Mycobacterium tuberculosis co-infected macrophages is dominated by M. tuberculosis

The resurgence of tuberculosis worldwide has closely mirrored the HIV pandemic. In regions like sub-Saharan Africa, a large proportion of individuals are co-infected with Mycobacterium tuberculosis and HIV. Macrophages are the reservoir host cells for both pathogens, however the interactions between both pathogens in co-infected cells remain poorly understood. Thus, the global gene responses of primary human macrophages following productive co-infection with highly purified HIV and M. tuberculosis were analyzed using cDNA microarrays. A broad range of genes was up-regulated in response to co-infection or M. tuberculosis infection of primary macrophages, including those encoding pro-inflammatory chemokines and cytokines, their receptors, signalling associated genes, type I IFN signalling genes and genes of the tryptophan degradation pathway. Real-time RT-PCR analysis confirmed up-regulation of a wide variety of genes including indoleamine 2,3 dioxygenase and Sp110 in M. tuberculosis and co-infected samples. Downstream analysis confirmed significant elevation of the chemokines CCL3, CCL4 and CCL8 in M. tuberculosis and co-infected culture supernatants. In contrast, the changes seen in gene expression following HIV infection alone were fewer in number and significantly less in magnitude. Thus, the effects of M. tuberculosis infection on global gene expression dominated the effects of HIV-1 in co-infected primary human macrophages.

Global gene expression profiles of ovarian surface epithelial cells in vivo

Epithelial ovarian cancer, the leading cause of death from gynecological malignancy in Western countries, is thought to arise from the ovarian surface epithelium (OSE). It has been postulated that the constant rounds of proliferation and repair following ovulation contributes to neoplastic transformation. However, there is little information on the genes and pathways which are involved in the normal functions of the ovarian epithelium, in particular genes that are hormone responsive and those central to functions such as proliferation and apoptosis during ovulation. We used laser microdissection and cDNA microarrays to profile gene expression specifically in mouse ovarian epithelial cells, first compared with other ovarian cells, and secondly between ovarian epithelium collected at different physiological stages. We identified over 1000 transcripts that were consistently more highly expressed in the ovarian epithelium compared with remaining ovarian cell types, including genes involved in cell growth, transcription, and cell adhesion. At the various physiological stages examined, the highest number of regulated genes was found during the estrous cycle, specifically on the evening of proestrus, coincident with the ovulatory surge of hormones and just prior to ovulation. The expression of several selected genes, identified by the microarray analysis, including Villin 2, Keratin 8, Arginine-rich mutated in epithelial tumors, and Tumor-associated calcium signal transducer 1, was validated by independent methods. The identification of genes expressed and regulated in the OSE, and characterization of the pathways involved, will contribute to a more detailed understanding of the ovarian epithelium transcriptome and ultimately lead to a better understanding of the aberrations leading to malignant transformation in the ovarian epithelium.

Genes implicated in multiple sclerosis pathogenesis from consilience of genotyping and expression profiles in relapse and remission

Background

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Although the pathogenesis of MS remains unknown, it is widely regarded as an autoimmune disease mediated by T-lymphocytes directed against myelin proteins and/or other oligodendrocyte epitopes.

Methods

In this study we investigated the gene expression profiles of peripheral blood cells from patients with RRMS during the relapse and the remission phases utilizing gene microarray technology. Dysregulated genes encoded in regions associated with MS susceptibility from genomic screens or previous trancriptomic studies were identified. The proximal promoter region polymorphisms of two genes were tested for association with disease and expression level.

Results

Distinct sets of dysregulated genes during the relapse and remission phases were identified including genes involved in apoptosis and inflammation. Three of these dysregulated genes have been previously implicated with MS susceptibility in genomic screens: TGFβ1, CD58 and DBC1. TGFβ1 has one common SNP in the proximal promoter: -508 T>C (rs1800469). Genotyping two Australian trio sets (total 620 families) found a trend for over-transmission of the T allele in MS in females (p < 0.13). Upregulation of CD58 and DBC1 in remission is consistent with their putative roles in promoting regulatory T cells and reducing cell proliferation, respectively. A fourth gene, ALOX5, is consistently found over-expressed in MS. Two common genetic variants were confirmed in the ALOX5 putatve promoter: -557 T>C (rs12762303) and a 6 bp tandem repeat polymorphism (GGGCGG) between position -147 and -176; but no evidence for transmission distortion found.

Conclusion

The dysregulation of these genes tags their metabolic pathways for further investigation for potential therapeutic intervention.

Determination of suitable housekeeping genes for normalisation of quantitative real time PCR analysis of cells infected with human immunodeficiency virus and herpes viruses

The choice of an appropriate housekeeping gene for normalisation purposes has now become an essential requirement when designing QPCR experiments. This is of particular importance when using QPCR to measure viral and cellular gene transcription levels in the context of viral infections as viruses can significantly interfere with host cell pathways, the components of which traditional housekeeping genes often encode. In this study we have determined the reliability of 10 housekeeping genes in context of four heavily studied viral infections; human immunodeficiency virus type 1, herpes simplex virus type 1, cytomegalovirus and varicella zoster virus infections using a variety of cell types and virus strains. This provides researchers of these viruses with a shortlist of potential housekeeping genes to use as normalisers for QPCR experiments.

Tackling obesity in men -- preliminary evaluation of men-only groups within a commercial slimming organization

BACKGROUND

Over Slimming World's 36-year history men have always made up a small percentage of the slimming organization's membership. Past company research suggested that men would feel more comfortable in men-only groups rather than mixed. In 2002, Slimming World set a target to raise the awareness among men about the dangers of being overweight and made practical weight-management solutions more accessible through a national network of men's groups.

AIM

To evaluate men's weight loss within these 'men-only' groups.

METHODS

Data analysed included those men having attended a group for at least 8 weeks.

RESULTS

At the point of data collection average BMI had decreased from 35.9 to 32.5 kg m(-2). At least 5% weight loss was achieved in 90% of the sample. In those who had been members for 24 weeks 69% achieved a 10% weight loss. Shift working did not affect weight loss success.

CONCLUSION

This data shows that overweight and obese men attending Slimming World are successful at losing weight in this environment and can achieve recommended health-related weight loss targets. There should be a move to get away from the mis-perception that slimming groups are only for women and raise awareness of the commercial option to men.

Gene expression and genotyping studies implicate the interleukin 7 receptor in the pathogenesis of primary progressive multiple sclerosis

Multiple sclerosis (MS) is an enigmatic disease of the central nervous system resulting in sclerotic plaques with the pathological hallmarks of demyelination and axonal damage, which can be directly or indirectly orchestrated by cells from the peripheral circulation. The majority of patients with MS follow a relapsing-remitting course in the early stages of the disease (RRMS) but most ultimately enter a secondary progressive phase (SPMS). About 10% of patients follow a primary progressive course from the onset (PPMS). We measured gene expression in whole blood of people with and without chronic progressive MS (CPMS), PPMS and SPMS, to discover genes which may be differentially expressed in peripheral blood in active disease, and so identify pathologically significant genes and pathways; and we investigated genetic differences in the promoters of dysregulated genes encoded in genomic regions associated with MS. If SPMS and PPMS were independently compared to the controls, there was little overlap in the set of most dysregulated genes. Ribosomal protein genes, whose expression is usually associated with cell proliferation and activation, were dramatically over-represented in the set of most down-regulated genes in PPMS compared to SPMS (P < 10(-4), chi(2)). The T cell proliferation gene IL7R (CD127) was also underexpressed in PPMS, but was up-regulated in SPMS compared to the controls. One interleukin 7 receptor (IL7R) promoter single nucleotide polymorphism (SNP), -504 C, was undertransmitted in PPMS trios (P = 0.05, TDT), and carriers of this allele were under-represented in PPMS cases from two independent patient cohorts (combined P = 0.006, FE). The four known IL7R promoter haplotypes were shown to have similar expression levels in healthy controls, but not in CPMS (P < 0.01, t test). These data support the hypothesis that PPMS has significant pathogenetic differences from SPMS, and that IL7R may be a useful therapeutic target in PPMS.

A study of the pharmacokinetic interaction between lamivudine and alpha interferon

OBJECTIVE

This study was designed to investigate any possible pharmacokinetic interaction between lamivudine and alpha interferon as potential candidates for combination therapy for the treatment of hepatitis B virus (HBV).

METHODS

Nineteen healthy male, Caucasian volunteers, aged 20-41 years and weighing 60.5-83.5 kg completed this open, non-randomised study. They each received a single, abdominal, deep s.c. injection of 10 mIU alpha interferon on day 1, followed by a wash-out period of at least 1 week. Subjects then began a 7-day course of lamivudine (100 mg) followed by a further 10-mIU alpha-interferon injection directly after oral lamivudine dosing. Blood and urine samples were taken pre- and post-dose for alpha-interferon and/or lamivudine assay.

RESULTS

Lamivudine was safe and well tolerated in all subjects. No adverse events were reported in subjects on lamivudine, whereas 106 adverse events considered attributable to alpha interferon were recorded. Statistical analysis of pharmacokinetic parameters indicated no significant effect of lamivudine on alpha-interferon pharmacokinetics. There was a small statistically significant reduction (approximately 10%) in the area under the lamivudine concentration time curve on co-administration with alpha interferon and a concomitant increase in clearance, which is not considered clinically relevant.

CONCLUSIONS

Alpha interferon and lamivudine can be co-administered with no requirement for dose modification, as there was no clinically significant difference in the pharmacokinetics of either drug.

A comparison of triprolidine and cyclizine on histamine (H1) antagonism, subjective effects and performance tests in man

1 The effects of triprolidine and cyclizine on the histamine skin response, performance tests and subjective effects were examined in a controlled, double-blind study in eight healthy volunteers. 2 Triprolidine was considerably more potent that cyclizine in inhibiting the skin response to histamine. Significant inhibition of flare size occurred at 1, 2 an 4 h after triprolidine 2.5 mg. A smaller but significant reduction occurred at 2 and 4 h after cyclizine 100 mg but not after the 50 mg dose. 3 Cyclizine 100 mg produced a significant increase in reaction time at 4.5 h compared with lactose. Smaller though non significant increases followed triprolidine and cyclizine 50 mg. 4 Subjective effects were seen only after cyclizine 100 mg when subjects were significantly more drowsy, feeble, muzzy, lethargic and dreamy than after lactose dummy. No significant changes followed triprolidine 2.5 mg or cyclizine 50 mg. 5 It was concluded that while cyclizine has antihistamine properties, these are weak compared with triprolidine, and are not seen with doses sufficiently low to avoid central nervous system impairment.

A comparison of the bronchodilator action of pseudoephedrine and ephedrine in patients with reversible airway obstruction

A double-blind randomised cross-over study was performed on 12 subjects suffering from reversible airway obstruction (asthma) to determine the relative bronchodilator effects of oral pseudoephedrine 60 mg, pseudoephedrine 180 mg, ephedrine 25 mg and matched placebo. Spirometry was used to measure vital capacity and forced expired volume in 1 s, and whole body plethysmography was used to measure specific airway conductance. Measurements were recorded before each drug was given, and 1 h and 2 h after each drug. Reversibility of the airway obstruction on each day of the study was demonstrated by significant improvements in all parameters of lung function in response to 400 micrograms of isoprenaline inhaled after the 2-h measurement. No significant bronchodilator effect could be shown following the ingestion of pseudoephedrine 60 mg or 180 mg. Only a week bronchodilator effect was demonstrated after ephedrine 25 mg in that the percentage change in vital capacity at 2 h after ephedrine was greater than that following either dose of pseudoephedrine or the placebo. It is concluded that oral pseudoephedrine in single doses of 60 mg or 180 mg has no significant bronchodilator action in man, and that a single dose of up to 180 mg pseudoephedrine does not cause tachycardia or hypertension.

Comparison of antibody responses and virus shedding following administration of trivalent oral poliomyelitis vaccines prepared either in monkey or human diploid cell substrates

Nineteen (22.9%) of 83 sera collected before vaccination from adult volunteers aged 21-64 years were without neutralizing antibody to poliomyelitis at levels of 0.15 i.u./ml for types I and II and 0.1 i.u./ml for type III. Some correlations were found between the history of previous vaccination and the presence of antibody but these were not well defined. Vaccination with a single dose of trivalent oral polio vaccine elicited fourfold or greater antibody responses to one or more poliomyelitis types in 53 (63.9%) volunteers, the percentage antibody resposnes being inversely related to the titre of antibody present before vaccination. Types I, II or III poliomyelitis virus were recovered from 76.8% of faecal samples collected 1 week after vaccination. The percentage recovery progressively declined thereafter until virus was recovered from 10.5% of samples collected 6 weeks after vaccination. Type for type, the titres and percentages of antibody responses and virus shedding in faeces were similar following trivalent oral poliomyelitis vaccines whether prepared in monkey or human diploid cell substrates. Some change in reproductive capacity temperature (r.c.t./40) marker was found in faecal isolates from volunteers vaccinated with monkey kidney and human diploid grown vaccines but no change in 'd' marker was found.

Normal values of transfer factor and transfer coefficients in healthy males and females

A population study was performed to obtain local normal values of the transfer factor for a respiratory laboratory providing a routine hospital service. Statistical analysis of the results obtained showed similar results to those of previous investigators for the transfer factor and alveolar volume. The transfer factor was found to be dependent on height, age and sex, while the alveolar volume depended only upon height and sex. Unlike previous investigations, however, the present study showed that the transfer coefficient was the same for women as for men and was related solely to age.

The comparative bioavailability of Lanoxin tablets and Lanoxicaps with and without sorbitol

(1) The mean cumulative urinary digoxin excretion over 8 days was compared in 8 healthy volunteers after single doses of digoxin administered as 3 Lanoxin tablets of 0.25 mg, 3 digoxin tablets of 0.2 mg, 12 Lanoxicaps without sorbitol of 0.05 mg, 6 Lanoxicaps without sorbitol of 0.1 mg digoxin, 3 Lanoxicaps without sorbitol of 0.2 mg and 3 Lanoxicaps with sorbitol of 0.2 mg. (2) There was no significant difference between the 8 day cumulative urinary excretion for any of the Lanoxicaps treatments. (3) Cumulative urinary excretion after 3 digoxin tablets of 0.2 mg was significantly (P less than 0.05) lower than after all other treatments. (4) Cumulative urinary excretion after 3 Lanoxin tablets of 0.25 mg was not significantly different from that after any of the Lanoxicaps treatments except 0.1 mg Lanoxicaps without sorbitol, it was significantly (P less than 0.05) lower after the latter. (5) Mean urinary excretion of digoxin was 60% of ingested dose for all Lanoxicaps treatments and was significantly (P less than 0.05) higher than the mean value of 50% for both tablet treatments. (6) Enhanced absorption of digoxin from Lanoxicaps was confirmed and shown to be unrelated to the sorbitol content of the capsule shell.

Drowsiness, impaired performance and tricyclic antidepressants drugs

1. The effects of amitriptyline, protriptyline, protriptyline, and a chemically related potential antidepressant, BW247, on performance tests and subjective ratings were studied. 2. Two groups of twelve healthy subjects received drugs and lactose dummy in identical capsules at weekly intervals according to a balanced design, under double-blind conditions, and with standarized tests and environment. 3. Amitriptyline produced the most marked effects, with significant (P less than 0.05) impairment in auditory vigilance after 6.25 mg. Auditory reaction time, tapping rate, arithmetic, and digit symbol substitutions were impaired by amitriptyline 12.5 and 25 mg and all doses produced increased ratings of mental sedation. The effects began 1.5 h after drug and lasted approximately 5 h. 4. Nortriptyline produced fewer effects which were later in onset. Tapping at 1.8 h and auditory vigilance at 3.5 to 4.5 h were impaired by nortriptyline 25 mg whereas reaction time was prolonged by both doses at 5 h. No change in rating of mental sedation occurred. 5. No significant change in performance or subjective ratings followed protriptyline 10 mg or BW247, 12.5 and 25 mg. 6. The findings are discussed in relation to the presence of secondary and tertiary amines on the side chain of the compounds, and their relative abilities to block neuronal uptake of noradrenaline and 5-hydroxytryptamine.

The influence of digoxin particle size on absorption of digoxin and the effect of propantheline and metoclopramide

1 The influence of particle size on absorption of digoxin was studied in ten healthy volunteers who received 0.5 mg digoxin as two standard Lanoxin tablets, or tablets containing micronized digoxin or large particle size digoxin. Tablets were given 30 min after 15 mg propantheline, 10 mg metoclopramine or a placebo tablet, and following an overnight fast. 2 The overall mean cumulative 4 day urinary excretion of digoxin was significantly lower (P less than 0.01) after large particle size digoxin than after standard or micronized digoxin. Mean cumulative urinary excretion following large particle size digoxin was reduced when administered after metoclopramide and increased after propantheline, the difference between these two treatments being significant (P less than 0.05). There was a significantly lower (P less than 0.05) overall mean cumulative excretion following standard by comparison with micronized digoxin. However, by comparison with placebo, neither metoclopramide nor propantheline significantly altered mean cumulative excretion after standard or micronized digoxin. Propantheline and metoclopramide affect absorption of digoxin from formulations of large particle size and slow dissolution rate only.

Influence of soft gelatin on digoxin absorption

1 The influence of encapsulation in soft gelatin on the absorption of digoxin from a solvent mixture of polyethylene glycol 400 90% W/W, ethanol 6% W/W, propylene glycol 3% W/W and water 1% W/W was studied in eight healthy volunteers. 2 Each volunteer received 0.6 mg digoxin as solution alone, as three intact capsules containing digoxin solution, as three capsules containing digoxin solution sectioned in half and as three capsules containing digoxin solution dissolved in water prior to administration. 3 There was no significant difference between the four treatments in terms of area under the plasma concentration--time curves for 7 h, peak plasma concentrations, time to peak or in the cumulative urinary excretion for 6 days. 4 It is suggested that a constituent of the solvent rather than the presence of or encapsulation within soft gelatin may be the determining factor in enhanced absorption of digoxin from soft gelatin capsules as compared to aqueous solution or tablets of rapid dissolution rate.

Effect of a standard breakfast on digoxin absorption in normal subjects

The influence of food on absorption of digoxin was studied in 6 healthy volunteers who received 1.0 mg digoxin as 4 tablets of Lanoxin either after an overnight fast, immediately after a standard breakfast, or 90 min after a standard breakfast. There was no significant difference between the three regimens in terms of area under the plasma concentration-time curve for 79 hr or in the 10-day cumulative urinary excretion. The mean peak plasma concentration was higher (p less than 0.05) when digoxin was given fasting (4.2 +/- 0.46 ng/ml) than immediately after food (2.8 +/- 0.24 ng/ml). The mean peak plasma concentration when digoxin was administered 90 min after food (3.3 +/- 0.30 ng/ml) was intermediate but not significantly different from either of the other mean peak concentrations. The results demonstrate that ingestion of food decreases rate but not extent of absorption of concurrently administered digoxin.

The nature of the beta-adrenoreceptor controlling plasma renin activity in man

1. Seven healthy sodium-replete male volunteer subjects remained supine during and for at least 1 h before the study. Heart rate and blood pressure were recorded continuously, and peripheral venous blood samples were taken every 15 min for determinations of plasma renin activity. 2. All subjects were studied twice: after 3 days of oral practolol (100 mg, three times daily) and after a similar period on placebo. Each study consisted of an intravenous infusion of isoprenaline in graded doses (0-20 microng/min in the placebo phase; 0-16 microng/min in the practolol phase), followed after rest for 2 h by an intravenous infusion of salbutamol (0-20 microng/min after placebo; 0-80 microng/min after practolol). 3. Both salbutamol and isoprenaline produced dose-related increases in systolic blood pressure, heart rate and plasma renin activity and decreases in diastolic pressure. 4. The increases in heart rate and plasma renin activity induced by either agonist were competitively blocked by practolol, as was the fall in diastolic blood pressure induced by isoprenaline; the salbutamol-induced fall of diastolic blood pressure was unaffected by practolol. 5. Comparison of dose ratio--1 estimates confirmed that practolol selectively blocked increases in heart rate and plasma renin activity due to salbutamol; no selective blockade against isoprenaline-induced changes was shown. 6. Selective blockade of salbutamol-induced changes indicate that a beta1-adrenoreceptor mediates changes in plasma renin activity.

A completely absorbed oral preparation of digoxin

Digoxin absorption was studied in healthy volunteers by determination of peak plasma concentrations, areas under plasma concentration curves, and urinary excretion after single-dose administration. By comparison with an aqueous solution, increased rate and extent of absorption occurred from experimental soft gelatin formulations of digoxin in solution. Enhanced bioavailability of the capsules was not affected by altered volume of contained solvent. Digoxin was considerably better absorbed from capsules than from tablets of moderately high dissolution rate. Mean percentage intestinal absorption was 75% from tablet and 97% from capsules. Reduced between-subject variability accompanied the enhanced absorption from capsules.

Residual effects of hypnotic drugs: evidence for individual differences on vigilance

Twelve healthy volunteers were given butobarbitone 100 and 200 mg, nitrazepam 5 and 10 mg and 2 lactose dummy treatments, at 23.00 hours at weekly intervals over 6 weeks according to a balanced design and using double blind conditions. Performance was studied between 09.00 hours and 17.00 hours the following day. Significant (P is less than 0.05) impairment of tapping rate and digit symbol substitution occurred. No significant differences occurred between performance after active drug and dummy in auditory vigilance, and subjective effects. Examination of individual differences in the response of subjects to the 4 hypnotic drug treatments, compared with their responses after dummy, indicated that subjects could be divided into two groups. One group consistently rated themselved as more alert after hypnotics and their vigilance performance improved. The other group consistently were more drowsy after hypnotics and their performance was impaired. It is suggested that the improvement in the first group resulted from improved sleep quality sufficient to counteract the residual effect of the hypnotic, whereas the second group merely showed the residual effects of the drugs.

[Double blind crossover study of pseudoephedrine and triprolidine alone and in combination in the treatment of allergic rhinitis (author's transl)]

In a double-blind crossover trial of pseudoephedrine 60 mg. and triprolidine 2.5 mg. alone and in combination, on 40 volunteers suffering from allergic rhinitis, both drugs were found superior to placebo in reducing the effects of allergic rhinitis and were of equal efficacy. The combination tablet was consistently better than either drug in several of the assessments and was the treatment which the subjects, as a whole, preferred. Side effects were not a problem with any of the medications.

A comparison of triprolidine and clemastine on histamine antagonism and performance tests in man: implications for the mechanism of drug induced drowsiness

The effects of triprolidine hydrochloride 1.25, 2.5 and 5 mg, clemastine 1 and 2 mg and lactose dummy administered orally, in a balanced order, at weekly intervals to 12 healthy volunteers, on the flare and weal responses to intradermal histamine injection, and also on both subjective effects and objective psychomotor tests were examined. The histamine response was significantly larger at 09.00 h falling through the day but increasing by late afternoon. Triprolidine produced a dose-related antagonism of both flare and weal response maximal at 3 h and wearing off after the lower doses at 8 h. Clemastine by contrast produced poor antagonism of histamine at 3 h but a marked effect at 5.5 and 8 h. Auditory vigilance was significantly (p less than 0.05) impaired by all doses of triprolidine 1 to 2 h after administration, but no change followed clemastine at this time. When tested 6 to 7 h after administration significant impairment followed both doses of clemastine but only the 5 mg dose of triprolidine. Both drugs prolonged reaction time in a dose-related manner at 2.5 and 5.0 h but the effects had worn off at 7 h. Digit symbol substitution was impaired by the top doses of both antihistamines but short term memory was unaffected. Subjective effects measured using analogue lines reflected the effects in the vigilance test, in that drowsiness and mental impairment were noted early after triprolidine, while clemastine produced maximal effects at 5 h. Subjects were ranked in order of magnitude of inhibition of both flare and weal, and impairment of vigilance, prolongation of reaction time and subjective drowsiness score. There was no indication of a significant correlation, using Spearman's test, between antagonism of histamine and effects on the central nervous system.

Maximal intestinal absorption of digoxin, and its relation to steady state plasma concentration

In a group of 8 volunteers, peak plasma digoxin concentrations and areas under 80-hour plasma concentration curves were significantly greater after 1 mg digoxin in paediatric elixir than after 4 0,25 mg tablets. Mean cumulative urinary excretion of digoxin over 12 days was 46.4 per cent after tablets, 53.6 per cent after elixir, and 70.8 per cent after intravenous injection. Mean percentage absorption was estimated to be 63 per cent from tablets and 75 per cent from elixir, but considerable between-subject variation was noted. Individual estimates of percentage absorption were significantly correlated with plasma concentrations in the steady state. Computer programmes to relate steady state plasma concentration to oral digoxin dosage take no account of absorptive capacity, are limited to gross approximations, and cannot replace determination of plasma concentration to assess the degree of digitalization.

The effect of co-trimoxazole on antitoxin response to tetanus toxoid

The effect of a 4-day course of co-trimoxazole (Septrin) on antitoxin response to tetanus vaccine was assessed in a double-blind study involving 22 healthy adults. The tetanus antitoxin levels were measured by in vivo and in vitro methods for up to 8 weeks after the first of two injections of tetanus vaccine, given 4 weeks apart. No sigificant difference was observed in the level of tetanus antitoxin produced in subjects who received co-trimoxazole (Septrin) in recommended therapeutic dosage during the first 4 days of the trial from that in subjects who received placebo tablets. The results indicate that a 4-day course of co-trimoxazole (Septrin) does not affect antibody production.

A comparison of plasma levels of L(+) pseudoephedrine following different formulations, and their relation to cardiovascular and subjective effects in man

Plasma concentrations of L(+)pseudoephedrine administered in clinically used dosages were determined by gas liquid chromatography using a nitrogen sensitive detector. They were measured after administered of an immediate release formulation (Sudafed) given in either a single dose of 180 mg, or three divided doses of 60 mg, and also after administration of two different sustained release preparations containing 180 mg. Ten subjects each received five treatment regimes, administration being ordered in a balanced design based on 2 five sided Latin squares. Significant differences were found between plasma concentrations and rates of urinary excretion of L(+)pseudoephedrine following administration of the different preparations. Peak plasma concentrations were greatest after 180 mg of the immediate release preparation while more sustained elevations of concentration followed administration of both sustained release preparations and the immediate release preparation in repeated doses. Despite these differences in plasma concentration significant differences in heart rate, blood pressure, or subjective ratings of mental state rarely occured, and the reasons for this are discussed. In a second study, one of the sustained release preparations was administered to 10 subjects at a dose of 180 mg twice daily for two weeks, and plasma concentrations and effects were measured. L(+)pseudoephedrine plasma levels reached a plateau in 3 days producing increased heart rate initially insomnia occurred but this disappeared after 3 days.

A Double-blind crossover trial of pseudoephedrine and triprolidine, alone and in combination, for the treatment of allergenic rhinitis

In a double-blind crossover trial of pseudoephedrine 60 mg and triprolidine 2.5 mg, alone and in combination, on 40 volunteers suffering from allergic rhinitis, both drugs were found superior to placebo in reducing the effects of allergic rhinitis and were of equal efficacy. The combination tablet was consistently better than either drug in several of the assessments and was the treatment which the subjects, as a whole, preferred. Side effects were not a problem with any of the medications.