Anaphylaxis following psyllium ingestion

Psyllium is a hydrophilic agent found in many bulk laxative preparations. We report the occurrence of an anaphylactic reaction in a patient after ingestion of a psyllium-containing laxative. IgE mediation of the reaction was suggested by a positive immediate skin test to psyllium, positive passive transfer skin test, lack of skin response during passive transfer with heat treated serum, and an elevated IgE (RAST) to psyllium seed.     

A simple statistical model for prediction of acute coronary syndrome in chest pain patients in the emergency department

Background  

Several models for prediction of acute coronary syndrome (ACS) among chest pain patients in the emergency department (ED) have been presented, but many models predict only the likelihood of acute myocardial infarction, or include a large number of variables, which make them less than optimal for implementation at a busy ED. We report here a simple statistical model for ACS prediction that could be used in routine care at a busy ED.     

Dissociated effects of diazepam and lorazepam on short-latency afferent inhibition

Peripheral nerve inputs have an inhibitory effect on motor cortex excitability at short intervals (short-latency afferent inhibition, SAI). This can be tested by coupling electrical stimulation of peripheral nerve with transcranial magnetic stimulation (TMS) of the motor cortex. SAI is reduced by the anticholinergic drug scopolamine, and in patients with Alzheimer's disease. Therefore, it is possible that SAI is a marker of central cholinergic activity important for memory function. The benzodiazepine lorazepam also reduces SAI. Since benzodiazepines impair memory formation, but do not do so uniformly, with a maximum amnesic effect after lorazepam but less or no effect after diazepam, we were interested in testing in this non-behavioural study to what extent the effects of lorazepam and diazepam on circuits involved in SAI could be dissociated. In addition, and for control, we tested the effects of lorazepam and diazepam on short-interval intracortical inhibition (SICI), a motor cortical inhibition mediated through the GABA_A receptor. Lorazepam markedly reduced SAI, whereas diazepam slightly increased it. In contrast, both benzodiazepines uniformly increased SICI. Our findings demonstrate opposite effects of lorazepam and diazepam on SAI, an inhibition modulated by central cholinergic activity, but the same effects on SICI, a marker of neurotransmission through the GABA_A receptor. This dissociation suggests, for the first time, that TMS measures of cortical inhibition provide the opportunity to segregate differences of benzodiazepine action in human central nervous system circuits.     

Development of host plasma cells during graft-versus-host reactions in mice

Graft-versus-host (GVH) reactions induced by thymus or spleen cells in newborn mice were found to trigger the development of plasma cells in the medullary areas of lymph nodes. No germinal centers were found. The plasma cells were found from the fourth day of the GVH reactions and increased in numbers over the next few days. On the 14th day the plasma cells were still present, although in lower numbers. Results of immunodiffusion experiments indicated that during GVH reactions induced by spleen cells, donor as well as host plasma cells develop. In contrast, induction of GVH reactions by thymus cells leads to the development of plasma cells, which probably originate exclusively from the host. Positive Coombs' reactions were detected 15–20 days after induction of GVH reactions and host immunoglobulins were found to contribute to the Coombs' positivity. The GVH reactions stimulated the formation of antibodies to sheep erythrocytes. This effect was more marked on 7 S than on 19 S antibody production.     

Molecular genetics of pseudoxanthoma elasticum: type and frequency of mutations in ABCC6

Pseudoxanthoma elasticum (PXE) is a systemic heritable disorder that affects the elastic tissue in the skin, eye, and cardiovascular system. Mutations in the ABCC6 gene cause PXE. We performed a mutation screen in ABCC6 using haplotype analysis in conjunction with direct sequencing to achieve a mutation detection rate of 97%. This screen consisted of 170 PXE chromosomes in 81 families, and detected 59 distinct mutations (32 missense, eight nonsense, and six likely splice-site point mutations; one small insertion; and seven small and five large deletions). Forty-three of these mutations are novel variants, which increases the total number of PXE mutations to 121. While most mutations are rare, three nonsense mutations, a splice donor site mutation, and the large deletion comprising exons 23-29 (c.2996_4208del) were identified as relatively frequent PXE mutations at 26%, 5%, 3.5%, 3%, and 11%, respectively. Chromosomal haplotyping with two proximal and two distal polymorphic markers flanking ABCC6 demonstrated that most chromosomes that carry these relatively frequent PXE mutations have related haplotypes specific for these mutations, which suggests that these chromosomes originate from single founder mutations. The types of mutations found support loss-of-function as the molecular mechanism for the PXE phenotype. In 76 of the 81 families, the affected individuals were either homozygous for the same mutation or compound heterozygous for two mutations. In the remaining five families with one uncovered mutation, affected showed allelic compound heterozygosity for the cosegregating PXE haplotype. This demonstrates pseudo-dominance as the relevant inheritance mechanism, since disease transmission to the next generation always requires one mutant allelic variant from each parent. In contrast to other previous clinical and molecular claims, our results show evidence only for recessive PXE. This has profound consequences for the genetic counseling of families with PXE.     

Non-linearities in the pharmacokinetics of di-(2-ethylhexyl) phthalate and metabolites in male rats

The disposition of the plasticizer di-(2-ethylhexyl) phthalate (DEHP) and four of its major metabolites was studied in male rats given single infusions of a DEHP emulsion in doses of 5, 50 or 500 mg DEHP/kg body weight. Plasma concentrations of DEHP and metabolites were followed for 24 h after the start of the infusion. The kinetics of the primary metabolite mono-(2-ethylhexyl) phthalate (MEHP) was studied separately.The concentrations of DEHP in plasma were at all times considerably higher than those of MEHP, and the concentrations of MEHP were much higher than those of the other investigated metabolites. In animals given 500 mg DEHP/kg, the areas under the plasma concentration-time curves (AUCs) of the other investigated metabolites were at most 15% of that of MEHP. Parallel decreases in the plasma concentrations of DEHP, MEHP and the and (-1) oxidized metabolites indicated that the elimination of DEHP was the rate-limiting step in the disposition of the metabolites. This was partly supported by the observation that the clearance of MEHP was higher than that of DEHP. Nonlinear increases in the AUCs of DEHP and MEHP indicated saturation in the formation as well as the elimination of the potentially toxic metabolite MEHP.     

Substance P antagonists and mucociliary activity in rabbit

Summary Substance P (SP) is known to accelerate mucociliary (m.c.) activity in the rabbit maxillary sinus in vivo. The physiological significance of this finding was investigated by testing three putative SP antagonists. [Arg⁵, d-Trp^{7, 9}, Nle¹¹]SP_5–11 could not be used as an antagonist because it stimulated m.c. activity. [d-Arg¹, d-Trp^{7, 9}, Leu¹¹]SP had no effect on the m.c. activity changes induced by SP. [d-Pro², d-Trp^{7, 9}]SP was found to be an effective antagonist, 1 mg/kg of this drug reversibly inhibiting both the effects of 0.1 g/kg SP and the stimulating effect of 1.0 g/kg bradykinin and 30.0g/kg capsaicin; the stimulating effect of 0.5 g/kg methacholine was not inhibited. It is suggested that bradykinin and capsaicin stimulate m.c. activity at least partly by releasing SP.The results of this investigation also support the view that the accelerating effect of SP on m.c. activity reflects physiological SP-mediated protective mechanisms in the airways. It is concluded that [d-Pro², d-Trp^{7, 9}]SP is a useful pharmacological tool for studying the role of SP in the control of m.c. actvity in rabbits.     

Cellular Immunity in COVID-19 Convalescents with PCR-Confirmed Infection but with Undetectable SARS-CoV-2–Specific IgG

We investigated immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a group of convalescent, potential blood donors in Germany who had PCR-confirmed SARS-CoV-2 infection. Sixty days after onset of symptoms, 13/78 (17%) study participants had borderline or negative results to an ELISA detecting IgG against the S1 protein of SARS-CoV-2. We analyzed participants with PCR-confirmed infection who had strong antibody responses (ratio >3) as positive controls and participants without symptoms of SARS-CoV-2 infection and without household contact with infected patients as negative controls. Using interferon-γ ELISpot, we observed that 78% of PCR-positive volunteers with undetectable antibodies showed T cell immunity against SARS-CoV-2. We observed a similar frequency (80%) of T-cell immunity in convalescent donors with strong antibody responses but did not detect immunity in negative controls. We concluded that, in convalescent patients with undetectable SARS-CoV-2 IgG, immunity may be mediated through T cells.     

The impact on quality of life of diet restrictions and disease symptoms associated with phenylketonuria: a time trade-off and discrete choice experiment study

The European Journal of Health Economics - Phenylketonuria (PKU) is a metabolic disorder leading to a deficiency in the metabolism of phenylalanine (Phe). Elevated Phe levels in the blood, tissue...