Vector analysis in partitioning of inspiratory muscle action in dogs

We considered the displacements and the pressure changes resulting from isolated contraction of 2 muscles as analogous to 2 vectors and those during simultaneous contraction as resultants. These were resolved into contributing components to calculate the contribution of each muscle group and partition the action of inspiratory muscles. Relative displacements of rib cage (delta RC) and abdomen (delta AB) and changes in transpulmonary (delta PL) and abdominal (delta Pab) pressures were obtained during spontaneous breathing, isolated contraction of rib cage muscle (RCM), diaphragmatic (DI), costal and crural diaphragm and passive inflation in 7 dogs. The diaphragm accounted for 58 +/- 19.8% SD of the chest wall displacement and 90 +/- 6.6% SD of the pressure swings during spontaneous breathing. The costal diaphragm accounted for 61 +/- 28.9% SD of the displacement produced by contraction of the entire diaphragm. Despite wide variability in the action of the diaphragm and its components, all animals breathed close to their relaxation characteristic. We conclude that there are marked differences in the degree of RCM recruitment between dogs in order to prevent chest wall distortions.

Glyphosate and Polyoxyethyleneamine Ingestion Leading to Renal, Hepatic, and Pulmonary Failure

ABSTRACT

Glyphosate is an organophosphorus compound and the active ingredient in commonly used herbicides, whereas polyoxyethyleneamine (POEA) is a nonionic surfactant often coupled with glyphosate in these herbicides to increase their efficacy. Cases of glyphosate-POEA ingestion have shown a variety of outcomes, ranging from skin and mucosal surface irritation to death. Here, we report mortality after ingestion of at least 237 mL of an herbicide confirmed to contain both glyphosate and POEA. The decedent's electronic medical record indicates presentation to the emergency department shortly after ingestion and rapid decompensation, with death occurring on the fourth day of admission. The autopsy report showed extensive pulmonary edema and congestion with no alimentary tract abnormalities. Microscopically, airway inflammation, edema, and hemorrhage were shown as well as pericentral necrosis and macrovascular hepatic steatosis. This case is unusual for several reasons including the fatal outcome in a young 30-year-old patient, the large volume of the herbicide consumed, the associated large volume aspirated, and the lung pathology associated with exposure to glyphosate-POEA since inhalation, and in this case, aspiration is an uncommon route of glyphosate-POEA exposure. This report therefore offers rare respiratory tract pathological findings and the clinical course after aspiration of a large volume of glyphosate-POEA.

Fatal Methemoglobinemia Due to Industrial Accident

This is a case of a male who fell into a vat of industrial chemicals while at work. He became unresponsive while being transported to the hospital and was pronounced dead shortly after arrival. At autopsy there was focal cyanosis, widespread first and second degree burns, chocolate-colored blood, and a postmortem methemoglobin concentration of 61.6%. An extensive search of English-language medical literature revealed that there has not been a reported case like this, in which a patient acquired methemoglobinemia by falling into a vat of industrial chemicals, was immersed in these oxidizing agents, and subsequently died. It is important when treating a victim of an accident such as this to note the chemicals to which the patient was exposed in order to understand their possible toxic effects. It is also important at autopsy to note the coloration of the blood because in this case, this is how the pathologist first suspected the possibility of methemoglobin and then ordered the appropriate diagnostic test.

Hemodynamic effects of lobar pulmonary artery occlusion in a porcine sepsis model

We induced severe pulmonary hypertension and acute lung injury in 6 pigs by Pseudomonas aeruginosa infusion. We studied the effect of pulmonary artery catheter inflation of a pulmonary artery catheter balloon in the left lower lobar pulmonary artery was accompanied by a significant (p less than 0.05, paired t test) increase in pulmonary artery pressure, a decrease in left atrial pressure, a decrease in cardiac output, and a decrease in mean arterial pressure. No significant changes occurred when the catheter was advanced into the wedged position without balloon inflation. Balloon inflation had no significant effect on these variables before bacterial infusion. We conclude that with sufficiently severe pulmonary hypertension in association with diffuse lung injury, lobar pulmonary artery occlusion may cause alterations in cardiac output and left atrial pressure. This may confuse interpretation of pulmonary artery catheter measurements.

Messenger RNA transport on lysosomal vesicles maintains axonal mitochondrial homeostasis and prevents axonal degeneration

In neurons, RNA granules are transported along the axon for local translation away from the soma. Recent studies indicate that some of this transport involves hitchhiking of RNA granules on lysosome-related vesicles. In the present study, we leveraged the ability to prevent transport of these vesicles into the axon by knockout of the lysosome-kinesin adaptor BLOC-one-related complex (BORC) to identify a subset of axonal mRNAs that depend on lysosome-related vesicles for transport. We found that BORC knockout causes depletion of a large group of axonal mRNAs mainly encoding ribosomal and mitochondrial/oxidative phosphorylation proteins. This depletion results in mitochondrial defects and eventually leads to axonal degeneration in human induced pluripotent stem cell (iPSC)-derived and mouse neurons. Pathway analyses of the depleted mRNAs revealed a mechanistic connection of BORC deficiency with common neurodegenerative disorders. These results demonstrate that mRNA transport on lysosome-related vesicles is critical for the maintenance of axonal homeostasis and that its failure causes axonal degeneration.

Anaesthesia for injection of bleeding oesophageal varices

Patients with haemorrhage from oesophageal varices associated with portal hypertension are poor risks for anaesthesia and surgery. One method of controlling such haemorrhage is injection of the oesophageal varices (sclero-therapy) via an oesophagoscope. Careful preoperative preparation and use of the Sengstaken-Blakemore tube in combination with the anaesthetic technique of intermittent Althesin and suxamethonium with artificial ventilation with nitrous oxide and oxygen enables sclerotherapy to be carried out successfully.

Simple mastectomy under local anaesthesia

Nine patients with locally advanced carcinoma of the breast underwent simple mastectomy under regional anaesthesia (1% lignocaine and 1:100,000 adrenaline). Preoperative sedation was provided by oral lorazepam. There were no technical problems, evidence of lignocaine toxicity or excessive operative blood loss and no wounds became infected.

The fate of gonococci in polymorphonuclear leucocytes: an electron microscopic study of the natural disease

The fate of gonococci in polymorphonuclear leucocytes (PMN) from men with acute gonorrhoea was studied using the electronmicroscope to look for ultrastructural damage in the bacteria. Our observations demonstrate that PMN degranulate normally into vacuoles containing gonococci and that obviously degenerate forms were present in older vacuoles. Morphologically intact gonococci were common in vacuoles containing evidence of recent degranulation suggesting that these organisms had only recently been phagocytosed. When urethral pus was suspended in tissue culture medium containing 1 μg/ml penicillin there were no “persisters” presumably because the intracellular organisms were killed by the PMN. Timed in vitro experiments using a proven virulent gonococcus demonstrated that gonococci degenerate within 30 to 60 min after phagocytosis.

Vector analysis in partitioning of inspiratory muscle action in dogs

We considered the displacements and the pressure changes resulting from isolated contraction of 2 muscles as analogous to 2 vectors and those during simultaneous contraction as resultants. These were resolved into contributing components to calculate the contribution of each muscle group and partition the action of inspiratory muscles. Relative displacements of rib cage (delta RC) and abdomen (delta AB) and changes in transpulmonary (delta PL) and abdominal (delta Pab) pressures were obtained during spontaneous breathing, isolated contraction of rib cage muscle (RCM), diaphragmatic (DI), costal and crural diaphragm and passive inflation in 7 dogs. The diaphragm accounted for 58 +/- 19.8% SD of the chest wall displacement and 90 +/- 6.6% SD of the pressure swings during spontaneous breathing. The costal diaphragm accounted for 61 +/- 28.9% SD of the displacement produced by contraction of the entire diaphragm. Despite wide variability in the action of the diaphragm and its components, all animals breathed close to their relaxation characteristic. We conclude that there are marked differences in the degree of RCM recruitment between dogs in order to prevent chest wall distortions.

Cognitive determinants of decisional capacity in neurodegenerative disorders

OBJECTIVE

Cognitive contributions to decisional capacity are complex and not well understood. Capacity to consent for research has been linked to executive function, but executive function assessment tools are imperfect. In this study, we examine the relationship between decisional capacity and a newly developed executive function composite score and determine whether cognitive performance can predict impaired decisional capacity.

METHODS

This is a cross sectional study of participants at the National Institutes of Health with frontotemporal dementia-amyotrophic lateral sclerosis spectrum disorders enrolled between 2017 and 2022. A structured interview tool was used to ascertain research decisional capacity. Study participant Uniform Data Set (v3.0) executive function (UDS3-EF) composite score, Clinical Dementia Rating Scale©, and Neuropsychiatric Inventory was determined.

RESULTS

A decrease in UDS3-EF composite score significantly increased the odds of impaired decisional capacity (OR = 2.92, 95% CI [1.66-5.13], p = 0.0002). Executive function was most impaired in frontotemporal dementia (-2.86, SD = 1.26) and least impaired in amyotrophic lateral sclerosis (-0.52, SD = 1.25) participants. The UDS3-EF composite score was also strongly correlated to the Clinical Dementia Rating Scale©.

INTERPRETATION

Decisional capacity is intrinsically related to executive function in neurodegenerative disorders, and executive dysfunction may predict a lack of decisional capacity alerting investigators of the need for additional scrutiny during the informed consent process.

Targeting complement C3a receptor resolves mitochondrial hyperfusion and subretinal microglial activation in progranulin-deficient frontotemporal dementia

Mutations in progranulin ( GRN ) cause frontotemporal dementia ( GRN -FTD) due to deficiency of the pleiotropic protein progranulin. GRN -FTD exhibits diverse pathologies including lysosome dysfunction, lipofuscinosis, microgliosis, and neuroinflammation. Yet, how progranulin loss causes disease remains unresolved. Here, we report that non-invasive retinal imaging of GRN -FTD patients revealed deficits in photoreceptors and the retinal pigment epithelium (RPE) that correlate with cognitive decline. Likewise, Grn -/- mice exhibit early RPE dysfunction, microglial activation, and subsequent photoreceptor loss. Super-resolution live imaging and transcriptomic analyses identified RPE mitochondria as an early driver of retinal dysfunction. Loss of mitochondrial fission protein 1 (MTFP1) in Grn -/- RPE causes mitochondrial hyperfusion and bioenergetic defects, leading to NF-kB-mediated activation of complement C3a-C3a receptor signaling, which drives further mitochondrial hyperfusion and retinal inflammation. C3aR antagonism restores RPE mitochondrial integrity and limits subretinal microglial activation. Our study identifies a previously unrecognized mechanism by which progranulin modulates mitochondrial integrity and complement-mediated neuroinflammation.

TMEM106B core deposition associates with TDP-43 pathology and is increased in risk SNP carriers for frontotemporal dementia

Genetic variation at the transmembrane protein 106B gene (TMEM106B) has been linked to risk of frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP) through an unknown mechanism. We found that presence of the TMEM106B rs3173615 protective genotype was associated with longer survival after symptom onset in a postmortem FTLD-TDP cohort, suggesting a slower disease course. The seminal discovery that filaments derived from TMEM106B is a common feature in aging and, across a range of neurodegenerative disorders, suggests that genetic variants in TMEM106B could modulate disease risk and progression through modulating TMEM106B aggregation. To explore this possibility and assess the pathological relevance of TMEM106B accumulation, we generated a new antibody targeting the TMEM106B filament core sequence. Analysis of postmortem samples revealed that the TMEM106B rs3173615 risk allele was associated with higher TMEM106B core accumulation in patients with FTLD-TDP. In contrast, minimal TMEM106B core deposition was detected in carriers of the protective allele. Although the abundance of monomeric full-length TMEM106B was unchanged, carriers of the protective genotype exhibited an increase in dimeric full-length TMEM106B. Increased TMEM106B core deposition was also associated with enhanced TDP-43 dysfunction, and interactome data suggested a role for TMEM106B core filaments in impaired RNA transport, local translation, and endolysosomal function in FTLD-TDP. Overall, these findings suggest that prevention of TMEM106B core accumulation is central to the mechanism by which the TMEM106B protective haplotype reduces disease risk and slows progression.

Diethyl ether, a chemical asphyxiant used as a prelude to homicide: a report of three cases

Homicides in which the victims are first subdued with a chemical asphyxiant rare unusual and quite rare. We report three cases in which victims were first overcome by ether containing compounds and then killed by other means of asphyxiation. The ether containing compounds used in these three cases were readily available commercial products. In two cases, the distinctive spectra of the volatile compounds in the decedents' blood, from the gas chromatograph and from the gas chromatograph/mass spectrometer, were compared with suspect ether containing products recovered during the scene investigations. In one case, an identical match was obtained. In the other case, the chromatographic spectra differed slightly from the compounds found at the scene, but the difference was explainable by metabolic breakdown of the compounds in vivo.

Regulation of cerebellar nitric oxide production in response to prolonged in vivo hypoxia

The aim of this study was to assess the influence of prolonged in vivo hypoxia on cerebellar nitric oxide (NO) production. Conscious rats were exposed to 10% O2 (balanced N2) for 12 or 48 hr (arterial PO2 between 35 and 39 mmHg). The animals were then killed, and the cerebella were quickly frozen. NO production was measured in vitro by monitoring the conversion of L-[3H]arginine to L-[3H]citrulline. Protein and mRNA expressions of the neuronal (nNOS) and endothelial (ecNOS) isoforms of nitric oxide synthases were assessed by using immunoblotting and semiquantitative reverse transcription-polymerase chain reaction, respectively. We also measured mRNA expression of GTP cyclohydrolase I, the rate-limiting enzyme in the synthesis of NOS cofactor, tetrahydrobiopterin, and mRNA and protein expressions of argininosuccinate synthase and argininosuccinate lyase, essential enzymes for the recycling of L-citrulline to L-arginine. Prolonged in vivo hypoxia resulted in a time-dependent increase in cerebellar nitric oxide synthase activity and a significant rise in mRNA and protein expressions of nNOS isoform; however, ecNOS protein expression declined significantly. There was also a rise in mRNA expression of GT cyclohydrolase I; however, neither mRNA nor protein expression of argininosuccinate synthase and argininosuccinate lyase changed significantly in hypoxic animals. These results suggest that prolonged hypoxia increases cerebellar NO formation as a result of upregulation of cerebellar nNOS expression, whereas ecNOS expression declines. We propose that cofactor availability for NO production may also increase during hypoxia because of upregulation of GTP cyclohydrolase I expression. Recycling of L-citrulline to L-arginine, however, remains unchanged.

Evaluation of intravenous tramadol for use in the prehospital situation by ambulance paramedics

INTRODUCTION

An evaluation of the opioid analgesic tramadol (Zydol, Searle United Kingdom) was carried-out by ambulance paramedics to assess its efficacy in providing pain relief in the prehospital situation.

METHOD

Type of subjects--Patients suffering severe pain from any cause uncontrolled by other simple methods. Number of subjects--101 patients received tramadol and 41 patients served as a control. Study design--Random, open study. Statistical tests--Pain score at scene and on arrival at hospital were compared using Fisher's exact tests (2 sides). Logistic regression analyses also were applied to other factors.

RESULTS

Pain scores improved for 93.1% of the tramadol treated patients and for 44.0% of the controls. A total of 30.7% of patients treated with tramadol complained of nausea after treatment compared with 17.1% before treatment and with 12.2% of the control patients.

CONCLUSIONS

Pain was significantly decreased by the administration of tramadol. It was safe with only minimal side effects, the major one being nausea. Suggestions are made for areas of further study.