Water Conservation Overrides Osmotic Diuresis During SGLT2 Inhibition in Patients With Heart Failure

BACKGROUND

Sodium-glucose cotransporter 2 inhibitors are believed to improve cardiac outcomes due to their osmotic diuretic potential.

OBJECTIVES

The goal of this study was to test the hypothesis that vasopressin-driven urine concentration overrides the osmotic diuretic effect of glucosuria induced by dapagliflozin treatment.

METHODS

DAPA-Shuttle1 (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment) was a single-center, double-blind, randomized, placebo-controlled trial, in which patients with chronic heart failure NYHA functional classes I/II and reduced ejection fraction were randomly assigned to receive dapagliflozin 10 mg daily or placebo (1:1) for 4 weeks. The primary endpoint was change from baseline in urine osmolyte concentration. Secondary endpoints included changes in copeptin levels and solute free water clearance.

RESULTS

Thirty-three randomized, sodium-glucose cotransporter 2 inhibitor-naïve participants completed the study, 29 of whom (placebo: n = 14; dapagliflozin: n = 15) provided accurate 24-hour urine collections (mean age 59 ± 14 years; left ventricular ejection fraction 31% ± 9%). Dapagliflozin treatment led to an isolated increase in urine glucose excretion by 3.3 mmol/kg/d (95% CI: 2.51-4.04; P < 0.0001) within 48 hours (early) which persisted after 4 weeks (late; 2.7 mmol/kg/d [95% CI: 1.98-3.51]; P < 0.0001). Dapagliflozin treatment increased serum copeptin early (5.5 pmol/L [95% CI: 0.45-10.5]; P < 0.05) and late (7.8 pmol/L [95% CI: 2.77-12.81]; P < 0.01), leading to proportional reductions in free water clearance (early: -9.1 mL/kg/d [95% CI: -14 to -4.12; P < 0.001]; late: -11.0 mL/kg/d [95% CI: -15.94 to -6.07; P < 0.0001]) and elevated urine concentrations (late: 134 mmol/L [95% CI: 39.28-229.12]; P < 0.01). Therefore, urine volume did not significantly increase with dapagliflozin (mean difference early: 2.8 mL/kg/d [95% CI: -1.97 to 7.48; P = 0.25]; mean difference late: 0.9 mL/kg/d [95% CI: -3.83 to 5.62]; P = 0.70).

CONCLUSIONS

Physiological-adaptive water conservation eliminated the expected osmotic diuretic potential of dapagliflozin and thereby prevented a glucose-driven increase in urine volume of approximately 10 mL/kg/d · 75 kg = 750 mL/kg/d. (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment [DAPA-Shuttle1]; NCT04080518).

Fibreglass dermatitis: diagnostic challenges and occupational interventions

Fibreglass dermatitis is a common occupationally acquired irritant contact dermatitis, where small spicules of fibreglass lodging in the stratum corneum result in mechanical irritation. We present two patients, an air-conditioning ducting worker and an injection moulding machine operator, who both presented with generalized pruritus. In the first case, polarized microscopy of a skin biopsy specimen demonstrated rare small spicules, with a diameter of 1 µm, lodged in the stratum corneum. In the second case, skin tape stripping demonstrated fibreglass particles, not found on skin biopsy. Proper work practices, personal hygiene and use of impervious barrier materials were recommended. The first patient did not return for follow-up, and the second patient's dermatitis resolved after handling of fibreglass-containing material was eliminated from his job scope. In conclusion, we present two cases of fibreglass dermatitis to illustrate the challenges in diagnosis and highlight strategies for prevention.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

1274 Impact of Covid 19 on Urgent Suspicion of GI Cancer Referral in a District General Hospital

Aim

Endoscopy services across United Kingdom were affected significantly since March 2020 due to Covid-19 pandemic. Services were reduced and were more selective. We aim to compare the impact on duration between referral to colonoscopy and the detection rate of pathology between February (pre- Covid) and August (Covid impacted) 2020.

Method

Data was analysed from a prospectively maintained database of patients referred for colonoscopy to Royal Alexandra Hospital, Scotland. Patients underwent colonoscopy in month of February and August 2020 were included. Bowel screening patients were excluded. Positive findings included diverticulosis, colitis, polyp and adenocarcinoma. P value of &lt; 0.05 was considered significant.

Results

Total number of patients included was 97 (55 in February, 42 in August). Median age was 61 and 69 years, respectively. Mean duration from referral to colonoscopy were 4 weeks in February and 7 weeks in August. qFIT test were found raised in 50.9% in February and 57.1% in August with positive findings of 47.3% in February and 66.7% in August. 46.4% in February and 16.7% in August had raised qFIT but normal findings (p &lt; 0.05). Two high grade dysplasia polyps and two adenocarcinomas were identified in February, none found in August.

Conclusions

Covid-19 pandemic has disrupted the endoscopic services prolonging the duration from referral to colonoscopy. qFIT test is more heavily relied to prioritise urgent colonoscopies resulting in more positive findings on colonoscopy. Cancer detection rate has reduced which is a consistent finding as the UK national endoscopy study. Massive efforts are needed to restore endoscopy services.

P3431Machine learning applied to energy waveform ECG for prediction of subclinical myocardial dysfunction

Background

Energy waveform (ew) ECG used continuous wavelet transforms (CWT) to create time-frequency energy characterisations. Although ewECG changes reflect myocardial disease, the optimal measures for prediction of subclinical left ventricular dysfunction (sLVD) are unclear.

Aim

Using machine learning, we investigated whether ewECG could predict sLVD in community subjects at risk of heart failure (HF).

Methods

Asymptomatic community subjects aged ≥65 yrs. with ≥1 non-ischaemic risk factor for HF underwent clinical evaluation, MyoVista (HeartSciences, Southlake, TX) ewECG and echocardiographic evaluation. sLVD was defined as systolic (global longitudinal strain, GLS≤16%) or diastolic (E/e' ≥15, E/e'>10 with left atrial enlargement, or impaired relaxation with other changes). A gradient boosting algorithm (supervised machine learning) with regularisation was implemented to predict sLVD using 362 ewECG features. The performance was assessed by precision, recall, F measure, precision-recall (PR) curve and receiver operating characteristic (ROC) curve. Feature importance was inspected by information gain node splitting.

Results

Of 97 subjects (age 71 (68–73) yrs., 53% female) 56 (58%) had sLVD. For prediction of sLVD, ewECG showed areas under PR and ROC curves of 0.86 and 0.8 respectively. The feature of greatest importance, with twice the importance of the second was a CWT frequency related to depolarisation.

Baseline characteristics Hypertension (%) 83 (86) Diabetes Mellitus (%) 34 (36) Atrial Fibrillation (%) 8 (8) BMI (IQR) 31 (27–34) LVMi (SD) 73 (23) Ejection fraction (SD) 60 (6) GLS (SD) 18 (3) E/e' (IQR) 8 (7–10) LAVi (IQR) 33 (28–40) IQR, Interquartile range; BMI, body mass index; LVMi, left ventricular mass index; GLS, global longitudinal strain; LAVi, left atrial volume index.

Prediction model performance

Conclusion

ewECG shows good predictive performance for sLVD in elderly subjects at risk of HF. HF prevention strategies incorporating ewECG to select individuals for echocardiographic evaluation should be considered.

Acknowledgement/Funding

Baker Heart and Diabetes Institute

MicroRNA-10b pleiotropically regulates invasion, angiogenicity and apoptosis of tumor cells resembling mesenchymal subtype of glioblastoma multiforme

Glioblastoma multiforme (GBM) is a heterogeneous disease despite its seemingly uniform pathology. Deconvolution of The Cancer Genome Atlas's GBM gene expression data has unveiled the existence of distinct gene expression signature underlying discrete GBM subtypes. Recent conflicting findings proposed that microRNA (miRNA)-10b exclusively regulates glioma growth or invasion but not both. We showed that silencing of miRNA-10b by baculoviral decoy vectors in a glioma cell line resembling the mesenchymal subtype of GBM reduces its growth, invasion and angiogenesis while promoting apoptosis in vitro. In an orthotopic human glioma mouse model, inhibition of miRNA-10b diminishes the invasiveness, angiogenicity and growth of the mesenchymal subtype-like glioma cells in the brain and significantly prolonged survival of glioma-bearing mice. We demonstrated that the pleiotropic nature of miRNA-10b was due to its suppression of multiple tumor suppressors, including TP53, FOXO3, CYLD, PAX6, PTCH1, HOXD10 and NOTCH1. In particular, siRNA-mediated knockdown experiments identified TP53, PAX6, NOTCH1 and HOXD10 as invasion regulatory genes in our mesenchymal subtype-like glioma cells. By interrogating the REMBRANDT, we noted that dysregulation of many direct targets of miRNA-10b was associated with significantly poorer patient survival. Thus, our study uncovers a novel role for miRNA-10b in regulating angiogenesis and suggests that miRNA-10b may be a pleiotropic regulator of gliomagenesis.

Influenza: current evidence and informed predictions

Every winter there are sharp rises in medical visits, hospitalizations and deaths from acute respiratory illness worldwide. Influenza is an important cause of these and is the only common viral respiratory pathogen with licensed vaccines available that are safe and effective in preventing disease. Over 50 countries have national vaccination programs focusing on the elderly population and those at high risk. In the USA, healthy children are also now offered the vaccine; routine immunization of the young, who are similarly vulnerable to hospitalization as the old, is likely to become universal. There remains a need for further improvement in vaccine effectiveness (both in the short- and long-term), vaccine administration and compliance. Recent technological developments raise the prospect of using new vaccine types, such as live attenuated and Vero cell-cultured vaccines, that are easier to administer and may induce broader immunity.

Assessment of the in vitro and in vivo genotoxicity of Thalomid (thalidomide)

Thalomid is the FDA-approved commercial formulation of thalidomide currently used in the US to treat erythema nodosum leprosum, a complication of leprosy. The genotoxicity of Thalomid thalidomide was assessed in the Ames reverse mutation, AS52/XPRT mammalian cell forward gene mutation, and mouse bone marrow micronucleus assays. The Ames and AS52 assays were performed with and without S9. In the Ames, Salmonella typhimurium strains TA1535, 1537, 98, 100, and 102 and Escherichia coli strain WP2 uvrA were used. Assays were performed by using plate incorporation and liquid pre-incubation systems at thalidomide doses of 50-10,000 microg/plate. In the AS52 assay, Chinese hamster ovary cells were plated with fortified Ham's F12 medium and incubated overnight. The medium was then incubated with 1-1000 microg/ml thalidomide. After a series of aspirations, washings, reconstitutions, and incubations, mutant AS52 cells were fixed and stained. Colonies were then counted and the relative survival frequencies compared to negative controls. In the mouse micronucleus assay, Crl:CD-1 albino mice were dosed with 500, 2,500, and 5,000 mg/kg thalidomide and sacrificed over 72 h. Femurs were flushed with fetal bovine serum and the suspensions centrifuged. The supernatant was aspirated and the cell pellet resuspended and stained. Polychromatic erythrocytes were scored for micronucleated polychromatic and normochromatic erythrocytes. Thalidomide did not increase revertant frequencies in all bacterial strains. It also did not produce any significant increase in the average mutant frequencies of AS52 cells and mouse micronucleated polychromatic erythrocytes. We conclude that Celgene's Thalomid thalidomide is non-genotoxic.

Lack of peripheral neuropathy in Beagle dogs after 53 weeks oral administration of thalidomide capsules

Thalidomide (Thalomid) is approved for use in the US to treat complications from leprosy. Peripheral neuropathy is a dose-limiting adverse event in humans. As part of a nonrodent regulatory toxicology study, Beagle dogs were fed orally via encapsulation for 53 weeks. A component of this study was to determine if the dogs developed peripheral neuropathy. Twenty-eight male and 28 female Beagle dogs approximately 8-10 months of age were used. They were dosed at 43, 200 or 1000 mg/kg for 53 weeks followed by a 4-week treatment-free recovery period. Nerve function was assessed by electrophysiological measurements of the tibial nerve prior to dosing and at weeks 13, 27, 38 and 51. Representative dogs from each group were sacrificed at 26, 53 and 58 weeks and histologic and ultrastructural evaluations were performed on the sural nerve. Thalidomide had no effect on sensory nerve conduction velocity, duration or amplitude of the action potential. At 27 weeks, mean sensory nerve action potential amplitude for females at 43 mg/kg was significantly greater than control but was not evident at 39 weeks. Mean duration of sensory nerve action potential seemed to increase with similar magnitude over time in all dose groups including controls. Histological and ultrastructural evaluation of sections of sural nerve did not identify treatment-induced differences between control and thalidomide-dosed animals after 26 and 53 weeks of treatment. Additionally, no differences were observed following a 5-week treatment-free period at week 58. In contrast to humans, Beagle dogs did not develop thalidomide-induced peripheral neuropathy under conditions of the study.

Effectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts

CONTEXT

A growing proportion of young children in the United States participate in day care, and these children are considered to be at high risk for influenza infection. Whether vaccinating day care children reduces household transmission of influenza is not known.

OBJECTIVE

To evaluate the effect of vaccinating day care children on reducing influenza-related morbidity among their household contacts.

DESIGN

Single-blind, randomized controlled trial conducted during the 1996-1997 influenza season.

SETTING

Ten day care centers for children of US Navy personnel in San Diego, Calif.

PARTICIPANTS

A total of 149 day care attendees (aged 24-60 months) and their families were randomized; 127 children and their 328 household contacts received 2 vaccine doses and were included in the analysis.

INTERVENTIONS

Inactivated influenza vaccine was administered to 60 children with 162 household contacts, and hepatitis A vaccine as a control was administered to 67 age-matched children with 166 household contacts.

MAIN OUTCOME MEASURES

Information regarding febrile respiratory illnesses and related morbidity for household contacts of influenza-vaccinated vs control children (subgrouped by influenza-vaccinated and unvaccinated contacts), obtained by telephone interviews with parents every 2 weeks from November 1996 through April 1997.

RESULTS

Influenza-unvaccinated household contacts (n = 120) of influenza-vaccinated day care children had 42% fewer febrile respiratory illnesses (P =.04) compared with unvaccinated household contacts of control children. Among school-aged household contacts (aged 5-17 years), there was an 80% reduction among contacts of vaccinated children (n = 28) vs contacts of unvaccinated children (n = 31) in febrile respiratory illnesses (P =.01), as well as reductions of more than 70% in school days missed (P =.02), reported earaches (P =.02), physician visits (P =.007), physician-prescribed antibiotics (P =.02), and adults who missed work to take care of ill children (P =.04).

CONCLUSIONS

These results indicate that vaccinating day care children against influenza helps reduce influenza-related morbidity among their household contacts, particularly among school-aged contacts. Future studies should be conducted in civilian populations to assess the full effect of vaccinating day care children against influenza. JAMA. 2000;284:1677-1682.

Reversal of heparin anticoagulation by recombinant platelet factor 4 in humans

BACKGROUND

Protamine is used to reverse the anticoagulant effects of heparin, but it can have important side effects. Platelet factor 4 (PF4) is a protein found in platelet alpha granules that binds to and thereby neutralizes heparin. We evaluated the safety and effectiveness of intravenous recombinant PF4 to neutralize heparin anticoagulation after cardiac catheterization in a phase 1, open-label trial.

METHODS AND RESULTS

The study group consisted of 18 patients having diagnostic cardiac catheterization. Heparin (5000 U) was given after vascular access was obtained. In the first 12 patients, additional heparin was given at the conclusion of the procedure so that all patients had activated coagulation times > 300 seconds before rPF4 was given. Three patients each received 0.5, 1.0, 2.5, or 5.0 mg/kg rPF4 over a period of 3 minutes at the conclusion of the catheterization procedure. In 6 additional patients, extra heparin was not given at the conclusion of the procedure, and 1.0 mg/kg rPF4 was given. Hemodynamic measurements, cardiac output, and serial blood tests were performed 5, 10, 20, and 30 minutes after rPF4 and then into the next 24 hours. There were no serious side effects in any patient, despite transient rPF4 levels as high as 14,870 ng/mL in the patients receiving 5.0 mg/kg. One patient receiving 2.5 mg/kg had a slight transient rise in liver enzymes possibly related to the rPF4. There were no important hemodynamic effects of rPF4 administration at any dose used. Doses of 2.5 and 5.0 mg/kg were uniformly effective in reversing the anticoagulant effect of heparin. At lower doses, rPF4 neutralized the effects of heparin in most but not all patients. Pharmacokinetic analysis suggested a monophasic and one-compartment clearance of the PF4-heparin complex. No neutralizing factors to rPF4 were detected in the samples collected 7 days after dosing.

CONCLUSIONS

rPF4, in doses ranging from 0.5 to 5.0 mg/kg over 3 minutes, had no serious side effects. Given in sufficient amounts, rPF4 can completely and rapidly reverse the anticoagulant effects of heparin.

Improving asthma documentation in a paediatric emergency department

OBJECTIVE

To improve documentation for children presenting to the Emergency Department (ED) of The Children's Hospital with acute asthma.

METHODOLOGY

In phase I, the documentation process was analysed using a standard total quality management (TQM) approach to identify specific problems leading to poor documentation. Fifty-two medical records of children presenting over a 3 week period were reviewed for nursing and medical documentation. A set of minimum criteria, consistent with the Paediatric Asthma Management Plan, were established for documentation by both medical and nursing staff. Following dissemination and education, compliance with documentation was evaluated and compared to an asthma survey performed in the ED in 1991. In phase II, a specific proforma for medical assessment was developed and 80 medical records of children presenting over a 3 week period were reviewed. Fifty-two (65%) with completed proformas were evaluated. The outcome measure was the documentation rate for minimum criteria established by TQM process.

RESULTS

In phase I, nursing compliance with documentation ranged from 46% for signs of respiratory distress to 83% for a past history of asthma and 100% for pulse rate. Doctors were similarly poor at documenting essential elements such as severity (31%), palpable pulsus paradoxus (29%), the child's usual doctor (46%) and follow-up arrangements (21-56%). In phase II, the documentation of the severity of acute asthma (42%) and of the child's usual doctor (42%) remained poor but there were statistically significant improvements in documentation of interval medications, palpable pulsus paradoxus, respiratory rate, pre-treatment oximetry, education, follow-up arrangements and communication letters.

CONCLUSION

The process of TQM has proved valuable in improving some aspects of documentation of children presenting to ED with acute asthma. It remains to be shown whether improved documentation will result in improved outcome.

Mirex inhibits bile acid secretory function in vivo and in the isolated perfused rat liver

The insecticides mirex and chlordecone suppress the biliary excretion of a wide variety of non-bile acid organic anions in vivo in the rat, and mirex inhibits the uptake of taurocholate (TC), a common bile acid, in isolated rat hepatocytes. We have therefore investigated the effects of mirex and chlordecone on bile acid secretory function (bile flow, bile acid concentration, bile acid secretory rate) in vivo and in the single-pass isolated perfused liver. Male Sprague-Dawley rats were orally dosed with corn oil, mirex (50 mg/kg), or chlordecone (18.75 mg/kg; in vivo studies only) for 3 consecutive days and experiments performed on Day 6. Mirex significantly increased liver weight from 12.2 +/- 0.8 to 20.8 +/- 1.3 g with no change in body weight whereas chlordecone had no significant effect on liver weight (11.9 +/- 0.7 g) or body weight. Mirex significantly decreased while chlordecone increased bile flow per gram liver in vivo; both compounds, however, increased bile flow when expressed per kilogram of body weight. Mirex and chlordecone significantly decreased the bile acid concentration in bile and the bile acid secretory rate (nmol/min/g liver and mumol/min/kg body weight). Studies in the isolated perfused liver were designed to determine the effect of mirex on the ability of the liver to extract increasing concentrations of [3H]TC from the perfusate and excrete it in the bile. Mirex treatment significantly decreased the TC extraction ratio by 40-89% and the hepatic intrinsic clearance by 85-95%. Mirex also significantly decreased the TC-induced choleresis, the concentration of TC in the bile, and the TC secretory rate. The data indicate that mirex treatment markedly inhibits the ability of the liver to extract TC from the blood/perfusate and concentrate it in the bile.

Mirex exposure inhibits the uptake of estradiol-17 beta(beta-D-glucuronide), taurocholate, and L-alanine into isolated rat hepatocytes

The insecticides mirex and chlordecone have previously been found to suppress the biliary excretion of a wide variety of compounds. In the present studies, the effects of mirex, chlordecone, and phenobarbital on the uptake of two endogenous organic anions, estradiol-17 beta(beta-D-glucuronide) (E217G), an estrogen metabolite, taurocholate (TC), a common bile acid, and an essential amino acid, L-alanine (L-Ala) (0.5 mM), into isolated rat hepatocytes was investigated. Female Sprague-Dawley rats were orally dosed with mirex (12.5, 25, and 50 mg/kg) or chlordecone (6.25, 12.5, and 18.75 mg/kg) dissolved in corn oil for 3 days and isolated rat hepatocytes were prepared 2 days later. Rats were also dosed orally with phenobarbital (50 mg/kg on the first day and 80 mg/kg for the next 4 days) dissolved in distilled deionized water, and isolated hepatocytes were prepared on the sixth day. Mirex significantly reduced the uptake of both organic anions (0.5, 10, and 50 microM E2 17G; 10 microM TC) into hepatocytes by 40-70%, whereas chlordecone had no effect on their uptake. Mirex at 50 mg/kg significantly reduced the Vmax for the low- and high-affinity E217G uptake sites by 70% and decreased the Km for the low affinity uptake site by 60%. Mirex also significantly decreased the Vmax for TC uptake from 1.11 to 0.82 nmol/min/mg protein but had no effect on its Km (23.2 vs 22.9 microM). Mirex at 50 mg/kg was also found to reduce the uptake of 0.5 mM L-Ala by nearly 40%. Phenobarbital had no effect on the uptake of E217G (0.5 microM), TC (10 microM), or L-Ala (0.5 mM). Mirex treatment had no effect on hepatic plasma membrane Na+,K(+)- or Mg2(+)-ATPase activity. Neither mirex nor chlordecone at 50-100 microM had any effect on the uptake of 10 microM TC when added directly to hepatocytes from naive rats. These results indicate that mirex decreases the transport of organic anions and L-Ala across the basolateral domain of the hepatocyte in addition to its inhibitory effects on biliary excretion.

The preparation of α-hydroxymethylserine

Convenient methods for the preparation of α-hydroxymethylserine in high yield by the treatment of the copper(II) complex of dihydro-1H,3H,5H- oxazolo[3,4-c]oxazole-7a-carboxylic acid with hydrogen sulphide or by catalytic hydrogenation of the complex are described.

The preparation and mass spectrometric studies of carboxy-substituted oxazoles derived from (S)-serine

The copper(11) complex formed by the reaction of bis((S)-serinato)copper(11) and formaldehyde under alkaline conditions was treated with sodium borohydride to give the sodium salt of dihydro-1 H,3H,5H- oxazolo[3,4-c]oxazole-7a-carboxylic acid. This reaction does not cause appreciable cleavage of the oxazole ring system. The methyl and ethyl esters of the acid were prepared and characterized by gas chromatography/mass spectrometry (g.c.-ms.). Breakdown patterns involving loss of formaldehyde are described.