Xenon and Sevoflurane Provide Analgesia during Labor and Fetal Brain Protection in a Perinatal Rat Model of Hypoxia-Ischemia

It is not possible to identify all pregnancies at risk of neonatal hypoxic-ischemic encephalopathy (HIE). Many women use some form of analgesia during childbirth and some anesthetic agents have been shown to be neuroprotective when used as analgesics at subanesthetic concentrations. In this study we sought to understand the effects of two anesthetic agents with presumptive analgesic activity and known preconditioning-neuroprotective properties (sevoflurane or xenon), in reducing hypoxia-induced brain damage in a model of intrauterine perinatal asphyxia. The analgesic and neuroprotective effects at subanesthetic levels of sevoflurane (0.35%) or xenon (35%) were tested in a rat model of intrauterine perinatal asphyxia. Analgesic effects were measured by assessing maternal behavior and spinal cord dorsal horn neuronal activation using c-Fos. In separate experiments, intrauterine fetal asphyxia was induced four hours after gas exposure; on post-insult day 3 apoptotic cell death was measured by caspase-3 immunostaining in hippocampal neurons and correlated with the number of viable neurons on postnatal day (PND) 7. A separate cohort of pups was nurtured by a surrogate mother for 50 days when cognitive testing with Morris water maze was performed. Both anesthetic agents provided analgesia as reflected by a reduction in the number of stretching movements and decreased c-Fos expression in the dorsal horn of the spinal cord. Both agents also reduced the number of caspase-3 positive (apoptotic) neurons and increased cell viability in the hippocampus at PND7. These acute histological changes were mirrored by improved cognitive function measured remotely after birth on PND 50 compared to control group. Subanesthetic doses of sevoflurane or xenon provided both analgesia and neuroprotection in this model of intrauterine perinatal asphyxia. These data suggest that anesthetic agents with neuroprotective properties may be effective in preventing HIE and should be tested in clinical trials in the future

Pain stretching behavior during labor.

<p>The time course (<b>A</b>) and counting (<b>B</b>) of stretches, either inward turning of the hind paw or straining of the abdomen, which represent uterus contraction-related pain 90 min prior to birth delivery. Dams from sevoflurane or xenon groups had a significant decrease of stretches compared to control group. Data are expressed as mean ± SEM (n = 4); **p<0.01. Bar = 100 µm.</p

c-Fos expression in the spinal.

<p>Rats were divided into naïve group (virgin female rats exposed in 30% oxygen balanced by 70% nitrogen), control group (parturient rats exposed in 30% oxygen balanced by 70% nitrogen), sevoflurane group (parturient rats exposed in 0.35% sevoflurane in 30% oxygen balanced by nitrogen), or xenon group (parturient rats exposed in 35% xenon in 30% oxygen balanced by nitrogen). Photomicrographs show c-Fos expression in the dorsal horn at the lumbosacral level of the spinal cord (<b>A</b>). <b>B</b> shows the quantification of c-Fos positive cells. Data are expressed as mean ± SEM (n = 4). **p<0.01. Bar = 100 µm. The inserted box indicates the area being subjected to high magnification image.</p

Neurocognitive behavior at PND 50.

<p><b>A</b> shows the average latencies, the time required for each animal to reach the hidden platform, of the four trials for the initial 5 days. <b>B</b> shows the area under curve (AUC) derived from <b>A</b>. <b>C</b> shows the percentage of the time the rats spent in the platform area in the probe trial on the 6^th testing day. Control group have significant neurocognitive impairment when compared to naïve group. There is no difference between sevoflurane, xenon groups and naïve group. <b>D</b> shows there is no difference in the average velocity in each group. Data are expressed as mean ± SEM (n = 5–6) and compared by one-way analysis of variance and Student-Newman-Keuls method. * p<0.05, **p<0.01.</p

Caspase 3 expression in the hippocampus.

<p>Pups from control, sevoflurane or xenon groups experienced intrauterine hypoxia, when the dams were exposed in different gases during labor. Pups from naïve group were from vaginal delivery from surrogate mother. Photomicrographs show caspase 3 expression in the hippocampus on PND3, CA1, (<b>A</b>, 20×). <b>B</b> shows the quantification of caspase 3 positive cells. Results are expressed as mean ± SEM (n = 5). *p<0.05. Bar = 100 µm. The inserted box indicates the area being subjected to high magnification image.</p

Morphological changes in the hippocampus.

<p>Photomicrographs show cresyl violet staining in CA1 region of hippocampus (<b>A</b>, 40×) on PND 7. Neuronal loss, cellular disorganization and shrinkage were attenuated in sevoflurane or xenon groups compared to control group. There is a significant difference in the number of healthy cells in control group, compared to all other groups (<b>B</b>). Results are mean ± SEM (n = 6). * p<0.05, **p<0.01.</p

Germline mismatch repair (MMR) gene analyses from English NHS regional molecular genomics laboratories 1996-2020: development of a national resource of patient-level genomics laboratory records.

Peer reviewed: TrueOBJECTIVE: To describe national patterns of National Health Service (NHS) analysis of mismatch repair (MMR) genes in England using individual-level data submitted to the National Disease Registration Service (NDRS) by the NHS regional molecular genetics laboratories. DESIGN: Laboratories submitted individual-level patient data to NDRS against a prescribed data model, including (1) patient identifiers, (2) test episode data, (3) per-gene results and (4) detected sequence variants. Individualised per-laboratory algorithms were designed and applied in NDRS to extract and map the data to the common data model. Laboratory-level MMR activity audit data from the Clinical Molecular Genetics Society/Association of Clinical Genomic Science were used to assess early years' missing data. RESULTS: Individual-level data from patients undergoing NHS MMR germline genetic testing were submitted from all 13 English laboratories performing MMR analyses, comprising in total 16 722 patients (9649 full-gene, 7073 targeted), with the earliest submission from 2000. The NDRS dataset is estimated to comprise >60% of NHS MMR analyses performed since inception of NHS MMR analysis, with complete national data for full-gene analyses for 2016 onwards. Out of 9649 full-gene tests, 2724 had an abnormal result, approximately 70% of which were (likely) pathogenic. Data linkage to the National Cancer Registry demonstrated colorectal cancer was the most frequent cancer type in which full-gene analysis was performed. CONCLUSION: The NDRS MMR dataset is a unique national pan-laboratory amalgamation of individual-level clinical and genomic patient data with pseudonymised identifiers enabling linkage to other national datasets. This growing resource will enable longitudinal research and can form the basis of a live national genomic disease registry