Transient anticonvulsant effects of time-restricted feeding in the 6-Hz mouse model

INTRODUCTION

Intermittent fasting enhances neural bioenergetics, is neuroprotective, and elicits antioxidant effects in various animal models. There are conflicting findings on seizure protection, where intermittent fasting regimens often cause severe weight loss resembling starvation which is unsustainable long-term. Therefore, we tested whether a less intensive intermittent fasting regimen such as time-restricted feeding (TRF) may confer seizure protection.

METHODS

Male CD1 mice were assigned to either ad libitum-fed control, continuous 8 h TRF, or 8 h TRF with weekend ad libitum food access (2:5 TRF) for one month. Body weight, food intake, and blood glucose levels were measured. Seizure thresholds were determined at various time points using 6-Hz and maximal electroshock seizure threshold (MEST) tests. Protein levels and mRNA expression of genes, enzyme activity related to glucose metabolism, as well as mitochondrial dynamics were assessed in the cortex and hippocampus. Markers of antioxidant defence were evaluated in the plasma, cortex, and liver.

RESULTS

Body weight gain was similar in the ad libitum-fed and TRF mouse groups. In both TRF regimens, blood glucose levels did not change between the fed and fasted state and were higher during fasting than in the ad libitum-fed groups. Mice in the TRF group had increased seizure thresholds in the 6-Hz test on day 15 and on day 19 in a second cohort of 2:5 TRF mice, but similar seizure thresholds at other time points compared to ad libitum-fed mice. Continuous TRF did not alter MEST seizure thresholds on day 28. Mice in the TRF group showed increased maximal activity of pyruvate dehydrogenase in the cortex, which was accompanied by increased protein levels of mitochondrial pyruvate carrier 1 in the cortex and hippocampus. There were no other major changes in protein or mRNA levels associated with energy metabolism and mitochondrial dynamics in the brain, nor markers of antioxidant defence in the brain, liver, or plasma.

CONCLUSIONS

Both continuous and 2:5 TRF regimens transiently increased seizure thresholds in the 6-Hz model at around 2 weeks, which coincided with stability of blood glucose levels during the fed and fasted periods. Our findings suggest that the lack of prolonged anticonvulsant effects in the acute electrical seizure models employed may be attributed to only modest metabolic and antioxidant adaptations found in the brain and liver. Our findings underscore the potential therapeutic value of TRF in managing seizure-related conditions.

Brain glycogen content is increased in the acute and interictal chronic stages of the mouse pilocarpine model of epilepsy

Glucose is the main brain fuel in fed conditions, while astrocytic glycogen is used as supplemental fuel when the brain is stimulated. Brain glycogen levels are decreased shortly after induced seizures in rodents, but little is known about how glycogen levels are affected interictally in chronic models of epilepsy. Reduced glutamine synthetase activity has been suggested to lead to increased brain glycogen levels in humans with chronic epilepsy. Here, we used the mouse pilocarpine model of epilepsy to investigate whether brain glycogen levels are altered, both acutely and in the chronic stage of the model. One day after pilocarpine‐induced convulsive status epilepticus (CSE), glycogen levels were higher in the hippocampal formation, cerebral cortex, and cerebellum. Opposite to expected, this was accompanied by elevated glutamine synthetase activity in the hippocampus but not the cortex. Increased interictal glycogen amounts were seen in the hippocampal formation and cerebral cortex in the chronic stage of the model (21 days post‐CSE), suggesting long‐lasting alterations in glycogen metabolism. Glycogen solubility in the cerebral cortex was unaltered in this epilepsy mouse model. Glycogen synthase kinase 3 beta (Gsk3b) mRNA levels were reduced in the hippocampal formations of mice in the chronic stage, which may underlie the elevated brain glycogen content in this model. This is the first report of elevated interictal glycogen levels in a chronic epilepsy model. Increased glycogen amounts in the brain may influence seizure susceptibility in this model, and this warrants further investigation.

Genome-wide transcriptomic analysis of the forebrain of postnatal Slc13a4+/- mice

OBJECTIVE

Sulfation is an essential physiological process that regulates the function of a wide array of molecules involved in brain development. We have previously shown expression levels for the sulfate transporter Slc13a4 to be elevated during postnatal development, and that sulfate accumulation in the brains of Slc13a4^+/- mice is reduced, suggesting a role for this transporter during this critical window of brain development. In order to understand the pathways regulated by cellular sulfation within the brain, we performed a bulk RNA-sequencing analysis of the forebrain of postnatal day 20 (P20) Slc13a4 heterozygous mice and wild-type litter mate controls.

DATA DESCRIPTION

We performed an RNA transcriptomic based sequencing screen on the whole forebrain from Slc13a4^+/- and Slc13a4^+/+mice at P20. Differential expression analysis revealed 90 differentially regulated genes in the forebrain of Slc13a4^+/- mice (a p-value of 0.1 was considered as significant). Of these, 55 were upregulated, and 35 were downregulated in the forebrain of heterozygous mice. Moreover, when we stratified further with a ± 1.2 fold-change, we observed 38 upregulated, and 16 downregulated genes in the forebrain of heterozygous mice. This resource provides a useful tool to interrogate which pathways may require elevated sulfate levels to drive normal postnatal development of the brain.

Understanding loneliness: a systematic review of the impact of social prescribing initiatives on loneliness

Aims:

The aim of this systematic literature review is to assess the impact of social prescribing (SP) programmes on loneliness among participants and the population.

Methods:

We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to search EBSCOHost (CINAHL Complete, eBook Collection, E-Journals, MEDLINE with Full Text, Open Dissertations, PsycARTICLES, and PsycINFO), UK National Institute for Health and Care Excellence (NICE), Web of Science Core Collection, and grey literature. We included studies measuring the effectiveness and impact of SP programmes in terms of loneliness. We excluded systematic reviews and studies without evaluations. Due to the absence of confidence intervals and the low number of studies, we conduct no meta-analysis.

Results:

From 4415 unique citations, nine articles met the inclusion criteria. The studies do not use uniform measures or randomised samples. All nine studies report positive individual impacts; three report reductions in general practitioner (GP), A&E, social worker, or inpatient/outpatient services; and one shows that belonging to a group reduces loneliness and healthcare usage.

Conclusion:

The findings of this systematic review indicate that individuals and service providers view SP as a helpful tool to address loneliness. However, evidence variability and the small number of studies make it difficult to draw a conclusion on the extent of the impact and the pathways to achieving positive change. More research is needed into the impact of SP programmes on participants, populations, and communities in terms of loneliness, isolation, and connectedness, especially in light of the surge in SP activity as a key part of pandemic response.

Evaluation of the association between insight and symptoms in a large sample of patients with schizophrenia

Background

The objective of the present study was to examine the association of insight into the illness with demographic variables and symptomatology in a sample of 1213 patients with schizophrenia.

Method

Data were collected with the Psychosis Evaluation tool for Common use by Caregivers (PECC), a semi-structured interview evaluating five symptom domains of schizophrenia and the insight items ‘awareness of having a mental disorder’ and ‘attributing symptoms to a mental disorder’.

Results

Insight was positively associated with educational level and inversely with overall symptom severity, and the positive, negative, excitatory and cognitive symptom domains. At symptom level, the items ‘delusions’, ‘grandiosity’, ‘poor rapport’, ‘social withdrawal’ and ‘guilt feelings’ showed the strongest associations with both insight items. Overall, correlations between insight and symptomatology were modest, explaining less than 30% of the variance in insight.

Conclusion

Lack of insight in schizophrenia is partially explained by clinical symptoms and demographic measures.

Transcriptional regulation of ependymal cell maturation within the postnatal brain

Background

Radial glial stem cells within the developing nervous system generate a variety of post-mitotic cells, including neurons and glial cells, as well as the specialised multi-ciliated cells that line the walls of the ventricular system, the ependymal cells. Ependymal cells separate the brain parenchyma from the cerebrospinal fluid and mediate osmotic regulation, the flow of cerebrospinal fluid, and the subsequent dispersion of signalling molecules via the co-ordinated beating of their cilia. Deficits to ependymal cell development and function have been implicated in the formation of hydrocephalus, but the transcriptional mechanisms underpinning ependymal development remain poorly characterised.

Findings

Here, we demonstrate that the transcription factor nuclear factor IX (NFIX) plays a central role in the development of the ependymal cell layer of the lateral ventricles. Expression of ependymal cell-specific markers is delayed in the absence of Nfix. Moreover, Nfix-deficient mice exhibit aberrant ependymal cell morphology at postnatal day 15, culminating in abnormal thickening and intermittent loss of this cell layer. Finally, we reveal Foxj1, a key factor promoting ependymal cell maturation, as a target for NFIX-mediated transcriptional activation.

Conclusions

Collectively, our data indicate that ependymal cell development is reliant, at least in part, on NFIX expression, further implicating this transcription factor as a mediator of multiple aspects of radial glial biology during corticogenesis.

Electronic supplementary material

The online version of this article (10.1186/s13064-018-0099-4) contains supplementary material, which is available to authorized users.

Combined allelic dosage of Nfia and Nfib regulates cortical development

Background:

Nuclear factor I family members nuclear factor I A and nuclear factor I B play important roles during cerebral cortical development. Nuclear factor I A and nuclear factor I B regulate similar biological processes, as their expression patterns, regulation of target genes and individual knockout phenotypes overlap. We hypothesised that the combined allelic loss of Nfia and Nfib would culminate in more severe defects in the cerebral cortex than loss of a single member.

Methods:

We combined immunofluorescence, co-immunoprecipitation, gene expression analysis and immunohistochemistry on knockout mouse models to investigate whether nuclear factor I A and nuclear factor I B function similarly and whether increasing allelic loss of Nfia and Nfib caused a more severe phenotype.

Results:

We determined that the biological functions of nuclear factor I A and nuclear factor I B overlap during early cortical development. These proteins are co-expressed and can form heterodimers in vivo. Differentially regulated genes that are shared between Nfia and Nfib knockout mice are highly enriched for nuclear factor I binding sites in their promoters and are associated with neurodevelopment. We found that compound heterozygous deletion of both genes resulted in a cortical phenotype similar to that of single homozygous Nfia or Nfib knockout embryos. This was characterised by retention of the interhemispheric fissure, dysgenesis of the corpus callosum and a malformed dentate gyrus. Double homozygous knockout of Nfia and Nfib resulted in a more severe phenotype, with increased ventricular enlargement and decreased numbers of differentiated glia and neurons.

Conclusion:

In the developing cerebral cortex, nuclear factor I A and nuclear factor I B share similar biological functions and function additively, as the combined allelic loss of these genes directly correlates with the severity of the developmental brain phenotype.

Transcriptional regulation of intermediate progenitor cell generation during hippocampal development

During forebrain development, radial glia generate neurons through the production of intermediate progenitor cells (IPCs). The production of IPCs is a central tenet underlying the generation of the appropriate number of cortical neurons, but the transcriptional logic underpinning this process remains poorly defined. Here, we examined IPC production using mice lacking the transcription factor nuclear factor I/X (Nfix). We show that Nfix deficiency delays IPC production and prolongs the neurogenic window, resulting in an increased number of neurons in the postnatal forebrain. Loss of additional Nfi alleles (Nfib) resulted in a severe delay in IPC generation while, conversely, overexpression of NFIX led to precocious IPC generation. Mechanistically, analyses of microarray and ChIP-seq datasets, coupled with the investigation of spindle orientation during radial glial cell division, revealed that NFIX promotes the generation of IPCs via the transcriptional upregulation of inscuteable (Insc). These data thereby provide novel insights into the mechanisms controlling the timely transition of radial glia into IPCs during forebrain development.

Should we abandon regional anesthesia in open inguinal hernia repair in adults?

Inguinal hernia repair is a common worldwide surgical procedure usually done in the outpatient setting. The purpose of this systematic review is to make an evidence-based meta-analysis to determine the possible benefits of regional (neuraxial block) anesthesia compared to general anesthesia in open inguinal hernia repair in adults. Cochrane Library, Medline, EMBASE, CINAHL, SCI-EXPANDED, SCOPUS as well as trial registries, conference proceedings and reference lists were searched. Only randomized controlled trials (RCT) that compare neuraxial block (spinal or/and epidural) anesthesia (NABA) and general anesthesia (GA) were included. Main outcome measures were postoperative complications, urinary retention and postoperative pain. Seven RCTs were included in this review. A total of 308 patients were analyzed with 154 patients in each group. Overall complications were evenly distributed in NABA and in GA group [OR 1.17, 95 % CI (0.52-2.66)]. Urinary retention was statistically less frequent in GA group compared to NABA group [OR 0.25, 95 % CI (0.08-0.74)]. Movement-associated pain score 24 h after surgery was significantly lower in NABA group [SMD 5.59, 95 % CI (3.69-7.50)]. Time of first analgesia application was shorter in GA group [SMD 8.99, 95 % CI 6.10-11.89]. Compared to GA, NABA appears to be a more adequate technique in terms of postoperative pain control. However, when GA is applied, patients seem to have less voiding problems.

Prevalence and prevention of dental injuries in young taekwondo athletes in Croatia

AIM

The aim of this study was to evaluate the occurrence of dental and facial injuries, the habit of wearing mouthguard and the awareness regarding injury prevention and first aid after tooth avulsion among young taekwondo athletes in Croatia.

MATERIALS AND METHODS

A survey on a sample of 484 taekwondo athletes was conducted, which included 271 male (56%) and 213 female (44%) athletes aged between 8 and 28 years. The questionnaire submitted to the athletes contained 15 questions about dental trauma, use of mouthguard, dental trauma prevention, level of awareness about tooth avulsion and replantation and disturbances associated with mouthguard use. Collected data were evaluated according to gender, age groups and duration of actively engagement in taekwondo. Descriptive statistics and Chi-square tests were used for comparisons between groups.

RESULTS

From the survey 300 (62%) of 484 athletes had sustained one serious injury and 103 (21%) had sustained an orofacial injury, while 194 (40%) had observed another player sustaining a dental injury. Higher number of orofacial injuries was observed in males (24%) than in females (18%). Furthermore, 98 (20%) athletes have experienced one or more dental injuries, and out of these 98 suffering dental injury 60 were male (61%) and 38 were female (39%). The frequency of orofacial injuries in the older group (42%) is higher than in three younger groups (younger cadets 25%; cadets 13%; juniors 20%) (p<0.05). Mouthguard wearing was recorded in 465 athletes (96%), 47.1% of them wear stock mouthguard, 47.6% wear boil and bite mouthguard, but only 5.3% were custom-made mouthguards. Most of them (96%) consider that mouthguards are useful for injury prevention in taekwondo.

CONCLUSION

The results of this survey show that dental and orofacial injuries occur in taekwondo in all age groups but mostly in the senior group. Taekwondo players know the importance of mouthguard use, but only 5% use custom made mouthguards. This is not adequate for dental injury prevention and highlights the important role of dental professional in education of athletes for advocating the use of custom made mouthguards.

Iminoborylene complexes: evaluation of synthetic routes towards BN-allenylidenes and unexpected reactivity towards carbodiimides

The iminoborylene complex [CpFe(PCy₃)(CO)(BNCMes₂)]⁺ undergoes MB metathesis reactivity with carbodiimides, resulting in FeB cleavage and the formation of isonitrile complexes.

Correction: Iminoborylene complexes: evaluation of synthetic routes towards BN-allenylidenes and unexpected reactivity towards carbodiimides

Correction for ‘Iminoborylene complexes: evaluation of synthetic routes towards BN-allenylidenes and unexpected reactivity towards carbodiimides’ by J. Niemeyer et al., Dalton Trans., 2015, DOI: 10.1039/c5dt00131e.

Red blood cell in vitro quality and function is maintained after S-303 pathogen inactivation treatment

BACKGROUND

Over the past decade there has been a growth in the development of pathogen reduction technologies to protect the blood supply from emerging pathogens. This development has proven to be difficult for red blood cells (RBCs). However the S-303 system has been shown to effectively inactivate a broad spectrum of pathogens, while maintaining RBC quality.

STUDY DESIGN AND METHODS

A paired three-arm study was performed to compare the in vitro quality of S-303-treated RBCs with RBCs stored at room temperature (RT) for the duration of the treatment (18-20 hr) and control RBCs stored at 2 to 6°C. Products were sampled weekly over 42 days of storage (n = 10) and tested using an array of in vitro assays to measure quality, metabolism, and functional variables.

RESULTS

During S-303 treatment there was a slight loss of RBCs and hemoglobin (Hb < 5 g). Hemolysis, glucose consumption, and potassium release were similar in all groups during the 42 days of storage. S-303-treated RBCs had a significantly lower lactate concentration and pH compared to the paired controls. The S-303-treated RBCs had significantly higher adenosine triphosphate than the RT and control RBCs. There was a significant loss of 2,3-diphosphoglycerate in the S-303-treated products, which was also observed in the RT RBCs. Flow cytometry analysis demonstrated similar RBC size, morphology, expression of CD47, and glycophorin A in all groups.

CONCLUSION

RBCs treated with S-303 for pathogen reduction had similar in vitro properties to the paired controls and were within transfusion guidelines.

Several natural indicators of radial well ageing at the Belgrade groundwater source, part 1

Over time, the radial collector wells of the Belgrade Groundwater Source, located in the alluvial sediments of the Sava River, exhibit a decline in discharge and a reduction in operating efficiency due to well ageing. An increase in hydraulic losses at the lateral screens, due to chemical and biochemical clogging, has been identified as the primary cause. Certain hydrogeological, hydrochemical and microbiological parameters reflect the well-ageing process and can, therefore, be considered as its indicators. An indicator-based determination of scale is an important aspect in the selection of appropriate well locations, structural characteristics, and maintenance approaches. Well ageing was studied over a period of 5 years (2005-2009). The objective was to investigate the causes of well ageing. The correlations established between the groundwater redox potential, the total iron concentration in groundwater, the grain-size distribution of the aquifer, and well discharge, are presented in the paper.

Splenic rupture following idiopathic rupture of the urinary bladder presenting as acute abdomen

Idiopathic rupture of the urinary bladder is an uncommon condition and represents less than 1% of all bladder rupture cases. In most of the cases the main etiological factor was heavy alcohol ingestion. A combined injury of the spleen and bladder is a very rare condition that is almost often associated with trauma and foreign bodies. In this paper we present the extremely rare clinical course of acute abdomen caused by a combined spontaneous intraperitoneal injury; spontaneous rupture of the urinary bladder and spleen. According to our opinion, spontaneous bladder rupture caused by bladder distension due to alcohol ingestion led to urinary ascites and abdominal distension. Finally, repeated minor abdominal blunt trauma during everyday life, to a moderately distended abdomen caused a spontaneous splenic rupture in the patient with abnormal coagulation studies.

Unusual attempted suicide by shooting through heart

Gunshot wounds in the heart are frequent suicidal injuries, especially in men. Most of them are lethal, but some cases of survival due to immediate and proper surgical treatment are reported. However, survival without specific treatment is extremely rare. In our case, a 44-year man attempted suicide by home-made shooting device. A special 12 cm long and 2.5 mm wide needle-like missile entered his body at the left anterior part of his chest, passed through the heart and lower lobe of right lung and exited at the right side of his back. The patient was able to move normally and he also looked for medical help immediately after attempting suicide. We found large atypical-shaped entrance wound on the anterior part of the chest, which was surgically treated, and tiny pointed exit wound under the right scapula. The patient was stable from cardio-circulatory and respiratory aspects from the time of admission to discharge from the hospital. We found only minimal pericardial bleeding (up to 10 mm thick) and there was no need for surgical intervention. In the next 2 weeks the haematoma absorbed spontaneously. The gunshot injury healed without any complication. Paranoid psychosis was diagnosed by psychiatrist and this probably had been the cause of attempting suicide. We think that the favorable outcome of the proved heart gunshot injury in our patient was due to the needle-shaped low-energy missile, which caused only tiny gunshot (stab) hole in the heart. Such a heart injury caused only minimal bleeding into the pericardial sac without heart tamponade.

Major histocompatibility complex class I-restricted presentation of protein antigens without prior intracellular processing

Proteins in their native form are incapable of stimulating antigen (Ag)-specific T cells, which can only recognize major histocompatibility complex (MHC)-bound peptides that have been generated by intracellular processing within antigen-presenting cells (APCs). Here, we show that APCs can trigger MHC class I-restricted T-cell responses after presenting proteins without conventional intracellular processing, provided the immunostimulatory MHC class I-binding peptide sequence is incorporated at the carboxy-terminal position. Such MHC-bound proteins do not stimulate T cells directly, because the contact between MHC/peptide complex and its cognate ligand is sterically hindered by the amino-terminal bulk of the protein. Removal of the latter via an extracellular Ag proteolysis by the T-cell- and/or APC-derived enzymes is required for effective T-cell stimulation. Our data challenge the established concept that only small peptides can bind to the MHC class I molecules.

Enhanced major histocompatibility complex class I-dependent presentation of antigens modified with cationic and fusogenic peptides

Soluble extracellular protein antigens are notoriously poor stimulators of CD8+ cytotoxic T-lymphocyte (CTL) responses, largely because these antigens have inefficient access to an endogenous cytosolic pathway of the major histocompatibility complex (MHC) class I-dependent antigen presentation. Here, we present a strategy that facilitates antigen penetration into the cytosol of antigen-presenting cells (APC) by addition to the antigen of charge-modifying peptide sequences. As a result of this intervention, the charge modification enhances antigen uptake into APC by counteracting the repulsive cell surface charge, and then endosomal membranes are disrupted with a subsequent release of antigen into the cytosol. This technology significantly improves MHC class I-dependent antigen presentation to CTL, enabling a more efficient generation of specific CTL immunity in vivo. The strategy described here has potential for use in developing efficient vaccines for antigen-specific immunotherapy of human malignancies.

Peptide and peptide mimetic inhibitors of antigen presentation by HLA-DR class II MHC molecules. Design, structure-activity relationships, and X-ray crystal structures

Molecular features of ligand binding to MHC class II HLA-DR molecules have been elucidated through a combination of peptide structure-activity studies and structure-based drug design, resulting in analogues with nanomolar affinity in binding assays. Stabilization of lead compounds against cathepsin B cleavage by N-methylation of noncritical backbone NH groups or by dipeptide mimetic substitutions has generated analogues that compete effectively against protein antigens in cellular assays, resulting in inhibition of T-cell proliferation. Crystal structures of four ternary complexes of different peptide mimetics with the rheumatoid arthritis-linked MHC DRB10401 and the bacterial superantigen SEB have been obtained. Peptide-sugar hybrids have also been identified using a structure-based design approach in which the sugar residue replaces a dipeptide. These studies illustrate the complementary roles played by phage display library methods, peptide analogue SAR, peptide mimetics substitutions, and structure-based drug design in the discovery of inhibitors of antigen presentation by MHC class II HLA-DR molecules.

Peptidomimetic compounds that inhibit antigen presentation by autoimmune disease-associated class II major histocompatibility molecules

We have identified a heptapeptide with high affinity to rheumatoid arthritis-associated class II major histocompatibility (MHC) molecules. Using a model of its interaction with the class II binding site, a variety of mimetic substitutions were introduced into the peptide. Several unnatural amino acids and dipeptide mimetics were found to be appropriate substituents and could be combined into compounds with binding affinities comparable to that of the original peptide. Compounds were designed that were several hundred-fold to more than a thousand-fold more potent than the original peptide in inhibiting T-cell responses to processed protein antigens presented by the target MHC molecules. Peptidomimetic compounds of this type could find therapeutic use as MHC-selective antagonists of antigen presentation in the treatment of autoimmune diseases.

Lyt phenotypes of primary cytotoxic T cells generated across the A and E region of the H-2 complex

Six different cell-mediated lympholysis (CML) combinations were established, four of which generated effector cells against the I-E, and two against the I-A molecule. The cell surface phenotype of effector cells was then determined by depletion of cytotoxic T lymphocyte (CTL) activity with antisera and rabbit complement (C) treatment. Both types of effector cells were completely eliminated by treatment with anti-Thy-1.2 antiserum plus C. Anti-Lyt-1.2 and C depleted anti-A and anti-E killer activity but did not eliminate CTL generated across a whole H-2 difference. One out of three different batches of anti-Lyt-2.2 antiserum did not deplete anti-A killer activity, while it efficiently eliminated CTL generated across the E region or whole H-2 difference. However, two batches of anti-Lyt-2.2 antiserum depleted also anti-A CTL activity. A quantitative difference between anti-A and anti-E CTL in terms of Lyt-2 expression was demonstrated by significant differences in recovery of killer activity, after treatment of these two types of CTL with a wide concentration range of the same anti-Lyt-2.2 antiserum and C. Thus it is concluded that anti-A killer cells have the cell surface phenotype of Thy-1+, Lyt-1, Lyt-2, whereas anti-E CTL are Thy-1+, Lyt-1, Lyt-2. The data are discussed in the context of a possible association of Lyt phenotypes of T cells with the type of MHC antigens they recognize.