A study of neuropsychiatric manifestations in COVID-19 infection in inpatients and its long-term outcomes in Malaysia

INTRODUCTION

This study aimed to determine the prevalence and association between the severity of COVID-19 and short and long-term neuropsychiatric symptoms, as well as the risk factors for the development of these symptoms.

MATERIALS AND METHODS

A prospective observational study was conducted between 1st October 2021 till September 2022 in the state of Johor, Malaysia. 300 patients with confirmed SARS-CoV-2 infection were randomly selected and followed up for six months. Data were analysed by using Chi-square test, Fisher's Exact test, Paired t test and Multiple logistic regression.

RESULTS

The prevalence of short-term neuropsychiatric symptoms was 78%, with anosmia being the most prevalent symptom. Long-term symptoms were found in 22.75% of patients, with headache being the most prevalent (p= 0.001). COVID-19 Stage 2 and 3 infections were associated with a higher risk of short-term neuropsychiatric symptoms, OR for Stage 2 infection was 5.18 (95% CI: 1.48-16.97; p=0.009) and for Stage 3 infection was 4.52 (95% CI: 1.76-11.59; p=0.002). Complete vaccination was a significant predictor of longterm symptoms with adjusted OR 3.65 (95% CI 1.22-10.91; p=0.021).

CONCLUSION

This study demonstrated that neuropsychiatric symptoms were common among COVID-19 patients in Johor, Malaysia and the risk of these symptoms was associated with the severity of the infection. Additionally, complete vaccination does not completely protect against long-term neuropsychiatric deficits. This is crucial for continuous monitoring and addressing neuropsychiatric symptoms in COVID-19 survivors.

A retrospective cross-sectional study on the risk factors and survival outcome of End Stage Kidney Disease patients receiving regular maintenance haemodialysis with COVID-19 infection in Hospital Enche' Besar Hajjah Khalsom, Kluang

INTRODUCTION

COVID-19 pandemic has affected healthcare services around the globe as hospitals were turned into designated hospitals to accommodate high risk groups of patients with COVID-19 infection including end stage kidney disease (ESKD) patients. In Malaysia, there was insufficient data on COVID-19 infection among ESKD patients. This study aims to determine factors and survival outcomes associated with COVID-19 infection among ESKD patients in a designated COVID-19 hospital in Malaysia.

METHODS AND MATERIALS

A retrospective cross-sectional study involving 80 haemodialysis (HD) patients recruited from March 2020 till March 2021. Patients' information and results was retrieved and evaluated. Risk factors affecting the COVID-19 mortality were analysed using a one-way analysis of variance (ANOVA) and binary logistic regression.

RESULTS

The mean age of the patients was 54 years who were predominantly Malays (87.5%) and living in rural areas. Majority of them had comorbidities such as diabetes mellitus (71%) and hypertension (90%). The most common presentations were fever (46%) and cough (54%) with chest radiographs showing bilateral lower zone ground glass opacities (45%). A quarter of the study population were admitted to the intensive care unit, necessitating mechanical ventilation. This study found that 51% of the patients were given steroids and 45% required oxygen supplementation. The COVID-19 infection mortality among the study population was 12.5%. Simple logistic regression analysis showed that albumin, Odd Ratio, OR=0.85 (95% Confidence Interval, 95%CI: 0.73, 0.98)) and absolute lymphocyte count OR=0.08 (95%CI: 0.11, 0.56) have inverse association with COVID-19 mortality. C-reactive protein OR=1.02 (95%CI: 1.01, 1.04), lactate dehydrogenase OR=1.01 (95%CI: 1.00, 1.01), mechanical ventilation OR=17.21 (95%CI: 3.03, 97.67) and high dose steroids OR=15.71 (95%CI: 1.80, 137.42) were directly associated with COVID-19 mortality.

CONCLUSION

The high mortality rate among ESKD patients receiving HD was alarming. This warrants additional infection control measures to prevent the spread of COVID- 19 infection among this vulnerable group of patients. Expediting vaccination efforts in this group of patients should be advocated to reduce the incidence of complications from COVID-19 infection.

Predictors of Non-adherence to Immunosuppressive Therapy in Asian Liver Transplant Recipients

BACKGROUND

Adherence to immunosuppressive medications has been shown to affect post-transplant outcomes. We aimed to determine the level of adherence to immunosuppressive therapy in liver transplant (LT) recipients and to elucidate factors associated with it, as well as patient preferences on the dosing schedule.

METHODS

LT recipients were recruited during transplant clinic follow-up. A validated Morisky 8-item questionnaire was completed by patients to assess their adherence to immunosuppressive therapy. Adherence was determined by the sum of the responses to the questionnaire. Low, medium, and high adherence were defined by a Morisky score of >2, 1 to 2, and 0, respectively. Data on the patient's socio-economic and clinical background, dosing schedule of immunosuppressant medications, and patient preferences were included in the questionnaire.

RESULTS

A total of 107 LT recipients were approached and 75 completed the questionnaire. The majority of patients (48/74, 64.9%) preferred a once-daily medication regimen. The proportion of high adherence was 24/75 (32.0%), medium adherence was 51/75 (42.7%), and low adherence was 19/75 (25.3%). Multivariate analysis showed younger age and post-transplant duration >5 years as independent predictors for low adherence. Among low-adherence patients, 16/19 (84.2%) patients were on a twice-daily regimen, and, of these, 14/16 (87.5%) preferred their medications to be reduced to once daily.

CONCLUSIONS

A significant proportion (68%) of LT recipients had low to moderate adherence to medications, with younger age and longer post-transplant duration of >5 years as independent predictors. Early identification of at-risk patients is essential to allow implementation of measures to improve adherence. Simplifying medication regimens to once daily is a potential way to improve adherence.

Abstract P6-06-16: Young age as a good prognostic factor in de novo metastatic breast cancer

Background

While breast cancer is relatively rare in young women under the age of 40, its incidence is increasing and accounts for up to 40% of all female cancers. Young age at diagnosis is associated with a poorer prognosis in early breast cancers; however little is known about the natural history of young women with metastatic breast cancer. We aim to evaluate the effect of age on breast-cancer specific survival (BCS) and overall survival (OS) for patients with de novo metastatic breast cancer using data from the SEER registry.

Methods

We retrospectively analyzed 14155 patients with de novo metastatic breast cancer from the SEER registry between 2000 and 2009. Young women were defined as 50 years and below and further subdivided into three groups: 20-34, 35-39, and 40-49 years. Age 50-69 years served as a comparison group. Unadjusted overall survival (OS) and breast cancer specific survival (BCS) were accessed using Kaplan-Meier plots and compared across groups using log-rank tests. Cox proportional hazards models were then fitted to determine the association between survival end point and age after adjusting for patient and tumor characteristics.

Results

546 (3.9%) patients were age 20-34 years, 750 (5.3%) were 35-39 years, 3049 (21.5%) were 40-49 years and 9810 (69.3%) patients were 50-69 years. Median BCS among patients age 20-34, 35-39, 40-49 and 50-69 years was 30, 33, 35, 28 months respectively (P<0.0001). Median BCS among patients with estrogen receptor positive disease who were age 20-34, 35-39, 40-49 and 50-69 years was 43, 42, 51, 37 months respectively (P<0.0001). Similarly median BCS among patients with estrogen receptor negative disease who were age 20-34, 35-39, 40-49 and 50-69 years was 21, 18, 18, 17 months respectively (P<0.0001). In the multivariable model compared to patients who were age 50 -69 years those aged 20-34 years (HR 0.88, 95% CI 0.78-0.99), 35-39 years (HR 0.82, 95% CI 0.74-0.91) and 40-49 years (HR 0.84, 95% CI 0.79-0.89) had a significantly decreased risk of death from breast cancer. Similar results were obtained for OS.

Conclusion

Younger patients defined by age less than 50 years had a better BCS and OS when compared against older age group in the setting of de novo metastatic breast cancer. This may be explained by lack of important comorbidities, relatively good performance status as well as ability to tolerate more lines of chemotherapies.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-16.

Resolution of adefovir-related nephrotoxicity by adefovir dose-reduction in patients with chronic hepatitis B

BACKGROUND

Chronic hepatitis B patients (CHB) treated with adefovir were followed up to evaluate nephrotoxicity and its outcome.

AIM

To assess the incidence of renal dysfunction during adefovir therapy in Asian patients and factors associated with it, and evaluate strategies to improve adefovir-related renal dysfunction and their impact on viral suppression.

METHODS

Chronic hepatitis B clinic patients from a tertiary hospital on adefovir treatment, with their clinical and laboratory parameters were extracted from the hospital electronic clinical database in an observational study design. Patients were excluded if they had liver/renal transplant, baseline renal impairment or were on dialysis. Adefovir-related renal dysfunction was defined as adefovir-related abnormal serum creatinine (ARASC) > 125 μmol/L (males), >90 μmol/L (females); adefovir-related abnormal GFR <60 mL/min; and adefovir-related increased serum creatinine >0.5 mg/dL, without other known causes of nephrotoxicity.

RESULTS

A total of 271/383 adefovir-treated patients were suitable for analysis and 33(12%) patients developed abnormal serum creatinine. Cumulative increase in proportion of patients with ARASC was 33.8% and GFR ≤60 mL/min was 38.3% by 6 years, while serum creatinine increase ≥0.5 mg/dL was 21.48% by 5 years. Using multivariate analysis, the only independent baseline predictor of ARASC was GFR ≤76.1 mL/min. Patients who had ARASC had similar levels of viral suppression to those who did not have ARASC. Those who had ARASC either continued adefovir (24%), switched therapy (24%) or had adefovir dose reduction (52%). ARASC resolved and GFR normalised in almost all patients after either switching therapy or reducing adefovir dose, with no difference between the two strategies (P = 0.737). Those with adefovir dose reduction had no significant increase in HBV DNA (P = 0.170).

CONCLUSIONS

Adefovir-related renal dysfunction occurred in a significant number of adefovir-treated patients, but reduction of the dose led to renal improvement without compromising treatment efficacy.

A dynamic plasmonic manipulation technique assisted by phase modulation of an incident optical vortex beam

A novel phase modulation method for dynamic manipulation of surface plasmon polaritons (SPPs) with a phase engineered optical vortex (OV) beam illuminating on nanoslits is experimentally demonstrated. Because of the unique helical phase carried by an OV beam, dynamic control of SPP multiple focusing and standing wave generation is realized by changing the OV beam's topological charge constituent with the help of a liquid-crystal spatial light modulator. Measurement of SPP distributions with near-field scanning optical microscopy showed an excellent agreement with numerical predictions. The proposed phase modulation technique for manipulating SPPs features has seemingly dynamic and reconfigurable advantages, with profound potential for development of SPP coupling, routing, multiplexing and high-resolution imaging devices on plasmonic chips.

Phase singularity of surface plasmon polaritons generated by optical vortices

We demonstrate an experimental result that shows the phase singularity of surface plasmon waves generated by the direct transform of optical vortices at normal incidence focused on a structureless metal surface. The near-field two-dimensional intensity distribution near the focal plane is experimentally examined by using near-field scanning optical microscopy and shows a good agreement with the finite-difference time-domain simulation result. The experimental realization demonstrates a potential of the proposed excitation scheme to be reconfigured locally with advantages over structures milled into optically thick metallic films for plasmonics applications involving plasmonic vortices.

Manipulation of surface plasmon polaritons by phase modulation of incident light

Manipulation of surface plasmon polaritons (SPP) by phase modulation of incident light beams is proposed with analytical and numerical verifications when an optical vortex (OV) beam is employed as an example. Fundamental functionalities of a plasmonic chip such as in-plane focusing, coupling and multiplexing of SPP by sequentially varying the topological charge of OV beam are demonstrated. Complementary to the manually-controlled optical-path-different technique reported in literature, the proposed method reveals a direct phase transform from OV beam to SPP with dynamic and reconfigurable advantages.

Deterministic relief dielectric structures to realize phase modulation of surface-plasmon polaritons

We propose a modified effective-refractive-index model for the design of relief dielectric structures on a metal surface to realize phase modulation of surface-plasmon polaritons (SPPs). In this model, the length of the dielectric structure is optimized to reach phase shifting between the SPP waves transmitted through dielectric structure and those directly propagated with the consideration of SPP losses. Specifically, a one-dimensional dielectric Fresnel zone plate is designed by employing the proposed model to demonstrate phase modulation of SPPs for the highest focusing efficiency.

Structured light for focusing surface plasmon polaritons

We propose a structureless method for focusing surface plasmon polaritons (SPPs) on a flat metal film under illumination of radially polarized cogwheel-like structured light beams. Without metal structures, the locally induced SPPs can further be propagated following the predefined patterns to form symmetric focal spots with dimensions beyond diffraction limit. Benefiting from the radial polarization, this method can be employed to pattern various center-symmetric evanescent distributions for generating SPPs reconfigurably. The SPPs will be propagating and focusing in radial directions.

Analysis of surface plasmon interference pattern formed by optical vortex beams

Following our recent experimental approach to excitation of surface plasmon polaritons induced by optical vortex beams [5], we report further analysis and verification of the surface plasmon interference pattern formed by locally excited standing surface plasmon polaritons in a metal/dielectric film. Our simulation model can be demonstrated by using angular spectrum representation. The generated standing interference pattern has potential as a resolution enhancement technique for sub-diffraction imaging.

Characterization of theLactococcus lactis pepNgene encoding an aminopeptidase homologous to mammalian aminopeptidase N

The nucleotide sequence of the pepN gene from Lactococcus lactis encoding a zinc-metallo aminopeptidase has been determined. The open reading frame of 2,538 base pairs encodes a protein with a calculated M(r) of 95,368, which agrees with the apparent M(r) of 95,000 of the gene product which was identified by polyclonal antibodies raised against the purified aminopeptidase. The amino acid sequence of the aminopeptidase of L. lactis was found to be similar to the corresponding enzymes of human, rat and mouse, with almost 30% of the residues identical. Also, a highly conserved area was identified which has similarity with the active site of thermolysin. A zinc-binding site, as well as the catalytic site for PepN, is predicted to lie within this conserved stretch. Putative promoter regions upstream of PepN were confirmed by primer extension analysis.

Clinical features of Nipah virus encephalitis among pig farmers in Malaysia

BACKGROUND

Between September 1998 and June 1999, there was an outbreak of severe viral encephalitis due to Nipah virus, a newly discovered paramyxovirus, in Malaysia.

METHODS

We studied the clinical features of the patients with Nipah virus encephalitis who were admitted to a medical center in Kuala Lumpur. The case definition was based on epidemiologic, clinical, cerebrospinal fluid, and neuroimaging findings.

RESULTS

Ninety-four patients with Nipah virus infection were seen from February to June 1999 (mean age, 37 years; ratio of male patients to female patients, 4.5 to 1). Ninety-three percent had had direct contact with pigs, usually in the two weeks before the onset of illness, suggesting that there was direct viral transmission from pigs to humans and a short incubation period. The main presenting features were fever, headache, dizziness, and vomiting. Fifty-two patients (55 percent) had a reduced level of consciousness and prominent brain-stem dysfunction. Distinctive clinical signs included segmental myoclonus, areflexia and hypotonia, hypertension, and tachycardia and thus suggest the involvement of the brain stem and the upper cervical spinal cord. The initial cerebrospinal fluid findings were abnormal in 75 percent of patients. Antibodies against Hendra virus were detected in serum or cerebrospinal fluid in 76 percent of 83 patients tested. Thirty patients (32 percent) died after rapid deterioration in their condition. An abnormal doll's-eye reflex and tachycardia were factors associated with a poor prognosis. Death was probably due to severe brain-stem involvement. Neurologic relapse occurred after initially mild disease in three patients. Fifty patients (53 percent) recovered fully, and 14 (15 percent) had persistent neurologic deficits.

CONCLUSIONS

Nipah virus causes a severe, rapidly progressive encephalitis with a high mortality rate and features that suggest involvement of the brain stem. The infection is associated with recent contact with pigs.

Fatal encephalitis due to Nipah virus among pig-farmers in Malaysia

BACKGROUND

Between February and April, 1999, an outbreak of viral encephalitis occurred among pig-farmers in Malaysia. We report findings for the first three patients who died.

METHODS

Samples of tissue were taken at necropsy. Blood and cerebrospinal-fluid (CSF) samples taken before death were cultured for viruses, and tested for antibodies to viruses.

FINDINGS

The three pig-farmers presented with fever, headache, and altered level of consciousness. Myoclonus was present in two patients. There were signs of brainstem dysfunction with hypertension and tachycardia. Rapid deterioration led to irreversible hypotension and death. A virus causing syncytial formation of vero cells was cultured from the CSF of two patients after 5 days; the virus stained positively with antibodies against Hendra virus by indirect immunofluorescence. IgM capture ELISA showed that all three patients had IgM antibodies in CSF against Hendra viral antigens. Necropsy showed widespread microinfarction in the central nervous system and other organs resulting from vasculitis-induced thrombosis. There was no clinical evidence of pulmonary involvement. Inclusion bodies likely to be of viral origin were noted in neurons near vasculitic blood vessels.

INTERPRETATION

The causative agent was a previously undescribed paramyxovirus related to the Hendra virus. Close contact with infected pigs may be the source of the viral transmission. Clinically and epidemiologically the infection is distinct from infection by the Hendra virus. We propose that this Hendra-like virus was the cause of the outbreak of encephalitis in Malaysia.

Use of capnography delaying the diagnosis of tracheal intubation

There was a delay in making the correct diagnosis of tracheal intubation in a parturient who developed severe bronchospasm after intubation because we relied on the capnogram.

Occult nitric oxide inhalation improves oxygenation in mechanically ventilated children

OBJECTIVES

Auto-inhalation of nitric oxide (NO) produced in the upper airways may have physiologic effects on lung function. For intubated patients, the upper airway source of NO is eliminated, but the hospital compressed air source from the environment is contaminated with varying levels of NO, creating an "occult" form of NO therapy. We examined the physiologic significance of occult inhaled NO in ventilator-dependent pediatric patients. We hypothesized that very low levels of NO contamination in inspired gas improve PaO2 in ventilator-dependent children.

STUDY DESIGN

Inspired NO levels at the mouth were measured by chemiluminescence in 4 pediatric subjects with normal lungs and 3 with parenchymal lung disease. Subjects were sequentially ventilated with first standard hospital gas (H1), switched to pure nitrogen-oxygen at a similar FIO2 but with no NO contamination (A2), hospital gas again (H2), the nitrogen-oxygen (A2) to control for time and sequence, and finally the nitrogen-oxygen mixture with supplemental NO in an amount equal to the NO previously measured in hospital gas (A2 + NO). Inhaled NO levels and PaO2 were recorded 15 minutes into each of the 5 steps. Two patients were studied a second time, remote from their first examination.

RESULTS

NO levels in inhaled hospital gas mixtures ranged from 13 to 79 ppb (mean H1 = 53.3 +/- 23.7 ppb, mean H2 = 53.2 +/- 20.7 ppb, mean A2 + NO = 45 +/- 15.3 ppb; P < .0001). Removing NO from ventilator gas decreased PaO2 in all subjects, whereas replacing NO in artificial gas restored PaO2 to baseline values (P < .0001).

CONCLUSION

Concentrations of NO in hospital compressed air are variable and have physiologic effects. The long-term implications of these findings remain to be defined.

Gain-of-function mutations in FcgammaRI of NOD mice: implications for the evolution of the Ig superfamily

It has been postulated that, during evolution of the Ig superfamily, modifications of the function of individual receptors might occur by acquisition of exons and their subsequent modification, though evidence of this is lacking. Here we have analysed the interaction of mouse IgG subclasses with high-affinity FcgammaRI (CD64) which contains three Ig-like domains and is important in innate and adaptive immunity. This analysis has identified a mechanism by which the postulated modification of newly acquired exons provides gains in function. Thus, the most widely distributed FcgammaRI allele in mice (e.g. BALB/c), bound only a single IgG subclass, IgG2a, with high affinity. However, non-obese diabetic (NOD) mice expressed a unique allele that exhibits broader specificity and, in addition to binding IgG2a, FcgammaRI-NOD bound monomeric IgG3 and bound IgG2b with high affinity, an IgG subclass not bound by FcgammaRI of other mouse strains, either as monomer or multivalent immune complexes. Analysis of mutants of FcgammaRI wherein segments of the interdomain junctions were exchanged between FcgammaRI-BALB and FcgammaRI-NOD identified these regions as having major influence in 'gain-of-function' by the NOD form of FcgammaRI. Nucleotide sequence analysis of intron/exon boundaries encoding the interdomain junctions of the FcgammaRI alleles showed these to have arisen by mutation to alter existing or create new mRNA splice donor/acceptor sites, resulting in generation of modified junctions.

Concealed air leak associated with large tidal volumes in partial liquid ventilation

Current ventilator strategies aim at maintaining an open lung and limiting both peak inspiratory pressures and tidal volumes to avoid alveolar distension. Perfluorocarbons, as well as being excellent solvents for oxygen and carbon dioxide, have the unique properties of being able to recruit dependent lung regions and improve pulmonary mechanics. Optimal ventilator strategies for partial liquid ventilation (PLV) have not yet been clearly defined. In the surfactant-depleted rabbit model, an approach involving a large tidal volume (VT) (15 ml/kg) and lung filled to FRC with perfluorocarbon (PFC) was compared with strategies involving a moderate VT (9 ml/kg) and partially filled lung (6 ml/kg), a moderate VT (9 ml/kg) and lung filled to FRC with PFC, and a large VT (15 ml/kg) and partially filled lung (6 ml/kg). PEEP was maintained at 5 cm H2O except in the moderate VT, partial-filling group, in which a PEEP of 9 cm H2O was used to maintain the rabbits for the duration of the experiment. Oxygenation was satisfactory in all groups, and peak inspiratory pressures were not significantly different. However, five of the 13 animals in the large-VT, PFC-filled lung group died of a pneumothorax prior to completion of the experiment. Of the eight animals in this group surviving the experiment, two had radiographic evidence of pneumothoraces, with an additional three animals having autopsy evidence of air leak. Of the 22 animals in the other groups, all survived with the exception of a single rabbit in the large VT, partial-filling group, which had both radiographic and autopsy evidence of air leak. We conclude that there is a significant risk of barotrauma in a PLV strategy in which a large VT is used in association with a lung filled to FRC with perfluorocarbon. Adequate gas exchange can be achieved with alternative ventilation strategies in combination with PLV.

Low levels of nitric oxide as contaminant in hospital compressed air: physiologic significance?

OBJECTIVES

To determine whether the levels of nitric oxide found in hospital compressed air have a clinically relevant effect on oxygenation in intubated patients with normal lungs.

DESIGN

Prospective study.

SETTING

Cardiothoracic and surgical intensive care unit in a university hospital.

PATIENTS

Twelve postoperative patients receiving mechanical ventilation.

INTERVENTIONS

Pure nitrogen and oxygen were substituted for hospital compressed air as a source of blending for correct FIO2.

MEASUREMENTS AND MAIN RESULTS

Hemodynamics and PaO2 were measured in nitrogen and oxygen used for blending oxygen during stable FIO2 levels. Inhaled nitric oxide was measured with a nitric oxide-chemiluminescence detector. There was no clinically relevant change in systemic hemodynamics. However, the PaO2 decreased significantly when nitrogen was used for blending. Inhaled nitric oxide levels varied from 2 to 550 parts per billion during use of hospital compressed air; no nitric oxide was detectable during use of nitrogen.

CONCLUSIONS

The low concentration of nitric oxide in hospital compressed air improves oxygenation in patients with normal lungs receiving mechanical ventilation.

Use of the endotracheal tube as a pharyngeal airway

An animal study was conducted to determine whether an endotracheal tube placed above the vocal cords in the pharynx can be used for ventilation. Four dogs undergoing general anesthesia were ventilated through an endotracheal tube placed in the oropharynx with the remainder of the airway occluded. Ventilation was performed for 3 of every 5 minutes during a total period of 25 minutes. Arterial PCO2 was compared in sequential samples alternating apnea and pharyngeal ventilation. Ventilation via the pharyngeal tube significantly reduced the arterial PCO2 from 48.8 mm Hg (SD 16) during apnea to 30.1 mm Hg (SD 10.9). Repeated measures ANOVAF = 8.2, P < .001. All PCO2 levels during ventilation were in or below the normal range of 34 to 46. Provided that the mouth and nose can be sealed, an endotracheal tube placed in the pharynx above the cords allows for adequate ventilation.

Immunological and electrophoretic study of the proteolytic enzymes from various Lactococcus and Lactobacillus strains

Cell extracts of various lactobacilli and two Lactococcus strains were investigated for their immunoresponse with monoclonal and polyclonal antibodies raised against various proteolytic enzymes from Lc. lactis. Except for Lactobacillus casei SBT 2233, none of the lactobacilli proteins showed immunoresponse with the monoclonal antibodies. With polyclonal antibodies raised against aminopeptidases N and C and endopeptidase of Lc. lactis an immunoresponse was observed. However, the molecular masses of the reactive bands on the blot were considerably different from those of the corresponding lactococcal peptidases, except for the band that reacted with polyclonal antibodies against aminopeptidase C. The polyclonal antibodies raised against X-prolyl-dipeptidyl aminopeptidase and tripeptidase did not show any immunoreaction. As a control, all antibodies reacted with the lactococcal proteins on the blot, with molecular masses corresponding to those reported for the proteinases and peptidases. The results clearly showed that most of the proteolytic enzymes of lactobacilli were immunologically different from those of lactococci. The proteolytic enzymes in the cell-free extracts were separated by non-denaturing PAGE and visualized by zymogram staining. The electrophoretic pattern of the proteolytic enzymes of lactobacilli was different from that of Lc. lactis. Both experiments indicate that the enzymes of the proteolytic system of lactobacilli are different from those of lactococci.

Comparison of proteolytic activities in various lactobacilli

A total of 169 Lactobacillus strains from 12 species (Lb. acidophilus, Lb. brevis, Lb. buchneri, Lb. casei, Lb. delbrueckii subsp. bulgaricus, Lb. delbrueckii subsp. delbrueckii, Lb. delbrueckii subsp. lactis, Lb. fermentum, Lb. helveticus, Lb. paracasei subsp. paracasei, Lb. plantarum and Lb. rhamnosus), isolated from raw milk and various milk products, and 9 Lactococcus lactis strains were evaluated for peptidase activities with five chromogenic substrates and a tryptic digest of casein. Within each species, the peptidase activity of the cell-free extracts of the strains varied. Furthermore, differences were observed between the Lactobacillus species and Lc. lactis. Lb. helveticus had by far the highest hydrolysing activities towards all substrates, indicating the presence of powerful aminopeptidases, X-prolyl-dipeptidyl aminopeptidases and proline iminopeptidases. Lb. delbrueckii subsp. bulgaricus possessed high hydrolysing activities towards substrates containing proline, alanyl-prolyl-p-nitroanilide and prolyl-p-nitroanilide. On the other hand, Lb. fermentum and Lb. brevis could be considered as weakly proteolytic species. A more detailed study with highly proteolytic Lactobacillus strains indicated that at least three different proteinases or endopeptidases were present. Compared with Lc. lactis, the Lactobacillus strains had a much lower hydrolytic action on glutamyl-glutamic acid, suggesting that glutamyl aminopeptidase was absent in lactobacilli.

99Tcm-pyrophosphate myocardial scintigraphy: the role of volume-rendered three-dimensional imaging in the diagnosis of acute myocardial infarction

The aim of this study was to evaluate the role of volume-rendered three-dimensional imaging in the diagnosis of acute myocardial infarction (AMI) using 99Tcm-pyrophosphate (99Tcm-PYP) scintigraphy in a diagnostically difficult group of patients. In total, 117 patients were studied using planar, single photon emission tomography (SPET) and 3-D volume-rendered imaging performed 3 h after receiving 555 MBq (15 mCi) of 99Tcm-PYP intravenously. 555MBq (15 mCi) of 99Tcm-PYP intravenously. Two teams of physicians reported in a blinded and random fashion on each planar, SPET and 3-D rotating image study. Individual reports were compared with reports that used all three imaging modalities in combination. Observer reproducibility was between 85 and 90% and inter-observer team agreement was between 87 and 91%. A score based on clinical history, electrocardiography, serum cardiac enzyme levels and cardiac risk factors was validated and used as a de facto 'gold standard' for AMI for 75 of the subjects for whom all these details were available. The sensitivity, specificity and overall accuracy of combined planar, SPET and 3-D rotating image modalities were all 84%. Analysis of each modality in isolation showed SPET imaging to have the highest sensitivity (74%) and specificity (89%). In combination with SPET and planar imaging, 3-D rotation image presentation increases diagnostic sensitivity without appreciably altering overall diagnostic accuracy. 99Tcm-PYP myocardial SPET imaging shows good utility in the diagnosis of AMI in diagnostically difficult patients.

Tripeptidase gene (pepT) of Lactococcus lactis: molecular cloning and nucleotide sequencing of pepT and construction of a chromosomal deletion mutant

The gene encoding a tripeptidase (pepT) of Lactococcus lactis subsp. cremoris (formerly subsp. lactis) MG1363 was cloned from a genomic library in pUC19 and subsequently sequenced. The tripeptidase of L. lactis was shown to be homologous to PepT of Salmonella typhimurium with 47.4% identity in the deduced amino acid sequences. L. lactis PepT was enzymatically active in Escherichia coli and allowed growth of a peptidase-negative leucine-auxotrophic E. coli strain by liberation of Leu from a tripeptide. Using a two-step integration-excision system, a pepT-negative mutant of L. lactis was constructed. No differences between the growth of the mutant and that of the wild-type strain in milk or in chemically defined medium with casein as the sole source of essential amino acids were observed.

Degradation and debittering of a tryptic digest from beta-casein by aminopeptidase N from Lactococcus lactis subsp. cremoris Wg2

The mode of action of purified aminopeptidase N from Lactococcus lactis subsp. cremoris Wg2 on a complex peptide mixture of a tryptic digest from bovine beta-casein was analyzed. The oligopeptides produced in the tryptic digest before and after aminopeptidase N treatment were identified by analysis of the N- and C-terminal amino acid sequences and amino acid compositions of the isolated peptides and by on-line liquid chromatography-mass spectrometry. Incubation of purified peptides with aminopeptidase N resulted in complete hydrolysis of many peptides, while others were only partially hydrolyzed or not hydrolyzed. The tryptic digest of beta-casein exhibits a strong bitter taste, which corresponds to the strong hydrophobicity of several peptides in the tryptic digest of beta-casein. The degradation of the "bitter" tryptic digest by aminopeptidase N resulted in a decrease of hydrophobic peptides and a drastic decrease of bitterness of the reaction mixture.

Cloning and sequencing of the gene for a lactococcal endopeptidase, an enzyme with sequence similarity to mammalian enkephalinase

The gene specifying an endopeptidase of Lactococcus lactis, named pepO, was cloned from a genomic library of L. lactis subsp. cremoris P8-2-47 in lambda EMBL3 and was subsequently sequenced. pepO is probably the last gene of an operon encoding the binding-protein-dependent oligopeptide transport system of L. lactis. The inferred amino acid sequence of PepO showed that the lactococcal endopeptidase has a marked similarity to the mammalian neutral endopeptidase EC 3.4.24.11 (enkephalinase), whereas no obvious sequence similarity with any bacterial enzyme was found. By means of gene disruption, a pepO-negative mutant was constructed. Growth and acid production of the mutant strain in milk were not affected, indicating that the endopeptidase is not essential for growth of L. lactis in milk.

Localization of Peptidases in Lactococci

The localization of two aminopeptidases, an X-prolyl-dipeptidyl aminopeptidase, an endopeptidase, and a tripeptidase in Lactococcus lactis was studied. Polyclonal antibodies raised against each purified peptidase are specific and do not cross-react with other peptidases. Experiments were performed by immunoblotting after cell fractionation and by electron microscopy of immunogold-labeled peptidases. All peptidases were found to be intracellular. However, immunogold studies showed a peripheral labeling of the X-prolyl-dipeptidyl aminopeptidase, the tripeptidase, and the endopeptidase. This peripheral location was further supported by the detection of these three enzymes in cell membrane fractions in which none of the two aminopeptidases was present.

Purification and characterization of an endopeptidase from Lactococcus lactis subsp. cremoris Wg2

An endopeptidase has been purified to homogeneity from a crude cell extract of Lactococcus lactis subsp. cremoris Wg2 by a procedure that includes diethyl-aminoethane-Sephacel chromatography, phenyl-Sepharose chromatography, hydroxylapatite chromatography, and fast protein liquid chromatography over an anion-exchange column and a hydrophobic-interaction column. Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated a molecular mass of the purified enzyme of 70,000 Da. The endopeptidase can degrade several oligopeptides into various tetra-, tri-, and dipeptides. The endopeptidase has no aminopeptidase, carboxypeptidase, dipeptidase, or tripeptidase activity. It is optimally active at pH 6.0 to 6.5 and in the temperature range of 30 to 38 degrees C. The enzyme is inactivated by the chemical agents 1,10-phenanthroline, ethylenedinitrilotetraacetate, beta-mercaptoethanol, and phenylmethylsulfonyl fluoride and is inhibited by Cu2+ and Zn2+. The ethylenedinitrilotetraacetate- or 1,10-phenanthroline-treated enzyme can be reactivated by Co2+. Immunoblotting with specific antibodies raised against the purified endopeptidase indicated that the enzyme is also present in other Lactococcus spp., as well as in Lactobacillus spp. and Streptococcus salivarius subsp. thermophilus.

A new optical transducer for arterial pressure measurement

A new optical pressure transducer system (Viggo) has been assessed and compared with a standard P10 transducer (Spectramed) using a similar 20-gauge cannula, both in vitro in terms of linearity and frequency response and in vivo using an animal model. The linearity of the transducers was comparable; the resonant frequencies were 106 Hz and 75 Hz, respectively. However, the resonant frequency of the complete Spectramed system including 150-cm tubing was 11 Hz. The frequencies at which the output amplitude error exceeded 10% of the initial amplitude for the Viggo and for P10 with and without 150-cm tubing were 32 Hz, 24 Hz and 4 Hz, respectively. The principal advantage of the new transducer is that it is sufficiently compact to be mounted directly in the cannula at the wrist, so obviating the use of connecting tubing between the transducer and the cannula.

Purification and Characterization of a Tripeptidase from Lactococcus lactis subsp. cremoris Wg2

A tripeptidase from a cell extract of Lactococcus lactis subsp. cremoris Wg2 has been purified to homogeneity by DEAE-Sephacel and phenyl-Sepharose chromatography followed by gel filtration over a Sephadex G-100 SF column and a high-performance liquid chromatography TSK G3000 SW column. The enzyme appears to be a dimer with a molecular weight of between 103,000 and 105,000 and is composed of two identical subunits each with a molecular weight of about 52,000. The tripeptidase is capable of hydrolyzing only tripeptides. The enzyme activity is optimal at pH 7.5 and at 55°C. EDTA inhibits the activity, and this can be reactivated with Zn 2+ , Mn 2+ , and partially with Co 2+ . The reducing agents dithiothreitol and β-mercaptoethanol and the divalent cation Cu 2+ inhibit tripeptidase activity. Kinetic studies indicate that the peptidase hydrolyzes leucyl-leucyl-leucine with a K m of 0.15 mM and a V max of 151 μmol/min per mg of protein.

Minimum airway pressure weaning. Weaning from mechanical ventilation at 50 breaths/minute by reduction of inflation pressure using a pressure generator

Ten patients, whose lungs were ventilated initially with intermittent positive pressure ventilation at conventional rates after myocardial revascularisation or cardiac valvular surgery, were weaned using a valveless high frequency jet ventilator at a constant rate of 50 breaths/minute. The withdrawal of ventilation was achieved, when clinical criteria permitted, by reduction of the tidal volume preset on the jet ventilator in successive stages; this was effected by stepwise decreases in the jet driving pressure. This new mode of weaning at a constant rate of 50 breaths/minute is associated with minimum peak airway pressures. Synchronisation of the patient's breathing with the valveless ventilator is not required and weaning is tolerated well by the patient. Arterial oxygen tension and saturation were maintained throughout weaning and did not decline after extubation of the trachea.

Purification and Characterization of an Aminopeptidase from Lactococcus lactis subsp. cremoris Wg2

An aminopeptidase was purified to homogeneity from a crude cell extract of Lactococcus lactis subsp. cremoris Wg2 by a procedure that included diethyl-aminoethane-Sephacel chromatography, phenyl-Sepharose chromatography, gel filtration, and high-performance liquid chromatography over an anion-exchange column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band with a molecular weight of 95,000. The aminopeptidase was capable of degrading several peptides by hydrolysis of the N-terminal amino acid. The peptidase had no endopeptidase or carboxypeptidase activity. The aminopeptidase activity was optimal at pH 7 and 40�C. The enzyme was completely inactivated by the p -chloromecuribenzoate mersalyl, chelating agents, and the divalent cations Cu 2+ and Cd 2+ . The activity that was lost by treatment with the sulfhydryl-blocking reagents was restored with dithiothreitol or β-mercapto-ethanol, while Zn 2+ or Co 2+ restored the activity of the 1,10-phenantroline-treated enzyme. Kinetic studies indicated that the enzyme has a relatively low affinity for lysyl- p -nitroanilide ( K m , 0.55 mM) but that it can hydrolyze this substrate at a high rate ( V max , 30 μmol/min per mg of protein).

The anaesthetic management of circulatory arrest

Induced circulatory arrest is a technique used to provide a period of operative stability in a variety of surgical procedures that might otherwise be technically unfeasible. The use of hypothermia and barbiturates for protection against cerebral ischaemia during circulatory arrest is reviewed against a background of the pathophysiology of cerebral ischaemia and possible future therapies are also suggested.

Experience with circulatory arrest and hypothermia to facilitate thoracic aortic surgery

A total of 12 patients underwent surgical repair for thoracic aortic dissections with a technique which included cardiopulmonary bypass, profound hypothermia, high-dose thiopentone and circulatory arrest. Seven of nine early postoperative survivors made a complete recovery on clinical criteria. There were three perioperative deaths and there was one late postoperative death from chronic renal disease. There were no deaths among those operated on electively. Neuropsychological testing may help to define the consequences of circulatory arrest on higher function.