Association Between Blood Groups and COVID-19 CT Severity: A Retrospective Analysis From a Tertiary Care Center

INTRODUCTION

The COVID-19 infection can have varied severity; presenting symptoms include fever, coughing, headaches, sore throats, exhaustion, muscle aches, loss of taste or smell, rhinorrhea, stomach pain, diarrhea, and vomiting. In various parts of the world, including India, researchers have looked into the relationship between blood type and the severity of SARS-CoV-2 infection. The aim of the study is to investigate the relationship between COVID-19 infection severity and blood group.

METHODOLOGY

A total of 1,222 COVID-19 patients with real-time reverse transcription-polymerase chain reaction (RT-PCR) confirmation of being COVID-positive were included in the study. Mortality rates, demographic information, comorbid illnesses, epidemiological information, laboratory test results, and comorbid disorders were all retrieved. Each participant's RH type and Groups A, B, O, and AB were determined. IBM SPSS software version 26 (IBM Corp., Armonk, NY) was used for the statistical analysis. For a normal distribution, quantitative variables were shown as mean standard deviation (SD), and for a non-normal distribution, median (interquartile range (IQR)). Frequency and percentages were used to present qualitative characteristics.

RESULTS

Out of the 1,222 patients included in the study, 369 were normal, 406 were mild, 317 were moderate, and 130 were severe based on COVID-19 CT severity scoring. Among the blood groups, O positive (+) was the most common with 503 (41.2%) study participants, and AB negative (-) was the least common with seven (0.6%) participants.

DISCUSSION

In our study, comparing various blood groups, blood group O individuals have the highest risk of developing severe COVID-19 illness, and blood group AB individuals have a reduced risk. In terms of Rh status, patients who are Rh-positive are at increased risk of developing severe COVID-19 infection when compared with Rh- individuals. In the Indian population, blood group O is the commonest, and blood group AB is the least prevalent. Most of the individuals were Rh+, and the rest were Rh-. This is attributed to the increased infection rate in individuals with O+ blood type seen in our study when compared with other studies.

CONCLUSION

The findings indicated that individuals with blood groups A, B, and AB may be at a higher risk of severe COVID-19 infection, while blood group O might provide some protective effect. These results align with previous studies worldwide, suggesting that blood groups could influence the susceptibility to and severity of viral infections. The study emphasizes the need for further research with larger sample sizes and diverse populations to validate these findings and explore the underlying mechanisms.

Scrotal Abdomen: Case Report and Management Principles

Hernias extending beyond the midpoint of the inner thigh in the standing position are called giant inguinal hernias or scrotal abdomen. They are rarely seen in common surgical practice. Huge inguinal hernias occur after years of neglect by the patient or in areas that are inaccessible to surgical services. Two cases of giant inguinal hernias which were managed successfully are presented here.

Case 1: 80-year-old male patient presented with left giant scrotal abdomen for the past 12 years. Preoperatively, the pulmonary function test was found to be normal for his age. He was given incentive spirometry for a week. Perioperatively, the sac contained the entire small bowel, sigmoid colon, and omentum with inter bowel loop adhesions. Adhesions were released and it was repaired by hernioplasty with left orchidectomy. In the postoperative period, the patient was put on non-invasive ventilation for two days and then later was weaned off.

Case 2: 42 years male patient presented with right-sided giant inguinoscrotal swelling for the past 15 years. The swelling was extending below midthigh. All the preoperative investigations were normal. Perioperatively, the sac contained omentum and small bowel and it was repaired by right hernioplasty. The postoperative period was uneventful and the patient recovered well.

These are interesting cases of giant inguinal hernias. The occurrence of such potentially dangerous surgical problems is more common in low-to-middle income countries owing to the unavailability of surgical services. The management involves specific measures to prepare the patient adequately preoperatively especially to prevent respiratory complications in the postoperative period.

Giant inguinal hernias can be comfortably managed if the patients are prepared adequately in the preoperative period. Their postoperative period will be uneventful if their pulmonary functions are normal.

Comparison of the Efficacy of Ultrasound-guided Pectoral versus Erector Spinae Plane Blocks for Postoperative Analgesia in Patients undergoing Modified Radical Mastectomy: A Randomised Controlled Trial

Introduction: Postmastectomy pain is more common following carcinoma breast surgery. Preventive analgesia for breast carcinoma includes administration of local infiltration or regional anaesthesia in the form of a paravertebral block, epidural, pectoral nerve block or intercostal block. Interfascial blocks, such as ultrasound guided pectoral nerve (PECS II) and Erector Spinae Plane (ESP) block have been shown to provide effective analgesia for mastectomy surgeries. Aim: To compare the postoperative analgesic efficacy of PECSII block and ESP block following mastectomy surgeries. Materials and Methods: The present study was a doubleblinded randomised controlled study. Patients scheduled for an elective unilateral modified radical mastectomy surgery of age 18-70 years, American Society of Anaesthesiologists (ASA) physical status I-II, were endrolled in the study. Sixty patients (ASA I-II) were divided into two groups. (30 in the PECS II group and 30 in the ESP group). The patients received respective blocks under ultrasound guidance after general anaesthesia. The primary outcome measured was the time of first request analgesia between groups. The secondary outcomes were postoperative Numeric Rating Scale (NRS) at eight different time-points (0.5, 1st, 2nd, 4th, 6th, 8th 12th and 24th hour) and intraoperative fentanyl requirement and haemodynamics (heart rate and mean arterial pressure). Total postoperative intravenous paracetamol consumption and rescue analgesic requirement in the first 24 hours postoperatively were noted. Statistical analysis was conducted by using Statistical Package for the Social Sciences (SPSS) version 20.0. Pearson’s Chi-square test was performed to compare ratios, and categorical variables were compared using Fisher’s exact test. A p-value value <0.05 was taken as statistically significant. Results: The time of first request analgesia was prolonged and significant in ESP block (255.5±48.76 minutes) than PEC II (197.5±31.35 minutes) (p=0.000347). In the postoperative ward, NRS scores at the 30th min, first and second hour were significantly lower in ESP block than PECS II group (2.3±0.4 vs. 5.2±0.8; 3.2±0.4 vs. 4.4±0.3, 3.7±0.4 vs. 5.2±0.4); p=0.041 p=0.047, p=0.037 respectively. From the second postoperative hour to the end of the observation period, there were no significant changes in NRS scores among groups. Postoperative paracetamol consumption was significantly higher in PECS II than ESPB (1.25±0.5 grams vs 2.33±1.2 grams, p<0.043824). There was no change in intraoperative fentanyl consumption and haemodynamics between groups. Conclusion: ESP block had better pain control, reduced postoperative pain scores and rescue analgesia than PECS II when given as preventive analgesia in mastectomy surgeries.

Monophasic Synovial Sarcoma of Foot Masquerading Squamous Cell Carcinoma

Synovial sarcoma being a rare sarcoma typically arises near articular surface most commonly around knee joint. Hereby, a case report of a 38-year-old male with complaint of cauliflower-like proliferative growth on the plantar aspect of left foot. It rapidly progressed in size over a period of one month. Wedge biopsy was done and diagnosis of malignant mesenchymal tumour was suggested. Further clinical workup of the case was carried out and the surgeons proceeded with amputation of the foot. Gross examination of specimen showed a large, ulcerated, nodular, exophytic, cauliflower-like growth over the plantar aspect of left foot along with areas of haemorrhage and necrosis masquerading more common squamous cell carcinoma. Histopathology revealed characteristic hypocellular and hypercellular areas showing pleomorphic spindle cells in fascicles and whorls suggesting monophasic synovial sarcoma. Immunohistochemistry stains further confirmed the diagnosis. The current case report highlights the rare presentation of synovial sarcoma as a cauliflower type of growth at a rare location.

Osteochondromatosis and osteochondroma involving bilateral patella and patellar tendon: a case report

We present a 22-year-old man with osteochondromatosis and osteochondroma involving bilateral patella and patellar tendon with restriction of joint movement and severe arthritis.

Isolation of free and membrane-bound polysomes and mRNA highly active in translation and reverse transcription from small discrete regions of rat brain

A procedure is described for the preparation of total polysomes, membrane-bound and free polysomes and polysomal mRNA from as little as 5 mg or less of brain tissue. These preparations were highly active when tested for translation and reverse transcription in vitro. Using this method, polysomes and mRNA from rat cerebral cortex, cerebellum, hippocampus and hypothalamus were compared. The results showed that membrane-bound polysomes were more active than free polysomes in protein synthesis. The activities of polysomes and mRNA for protein and cDNA synthesis were dependent on the specific brain structures from which they were obtained. Polysomes from cerebellum and hypothalamus incorporated amino acids more actively than those from cerebral cortex or hippocampus, when tested in a reticulocyte lysate system. Cerebellar mRNA also showed the highest activity for cDNA syntehsis as compared to mRNAs from the other three tissues.

Restriction/Modification systems and restriction endonucleases are more effective on lactococcal bacteriophages that have emerged recently in the dairy industry

Recently, eight lytic small isometric-headed bacteriophages were isolated from cheese-manufacturing plants throughout North America. The eight phages were different, but all propagated on one strain, Lactococcus lactis NCK203. On the basis of DNA homology, they were classified in the P335 species. Digestion of their genomes in vitro with restriction enzymes resulted in an unusually high number of type II endonuclease sites compared with the more common lytic phages of the 936 (small isometric-headed) and c2 (prolate-headed) species. In vivo, the P335 phages were more sensitive to four distinct lactococcal restriction and modification (R/M) systems than phages belonging to the 936 and c2 species. A significant correlation was found between the number of restriction sites for endonucleases (purified from other bacterial genera) and the relative susceptibility of phages to lactococcal R/M systems. Comparisons among these three phage species indicate that the P335 species may have emerged most recently in the dairy industry.

Differentiation of Two Abortive Mechanisms by Using Monoclonal Antibodies Directed toward Lactococcal Bacteriophage Capsid Proteins

Monoclonal antibodies were used to monitor the accumulation of the major capsid protein of the lactococcal small isometric bacteriophage u136 (P335 species) over the course of a one-step growth curve. A sandwich enzyme-linked immunosorbent assay was then used to distinguish two abortive phage resistance mechanisms, Hsp and Prf. Capsid protein production of u136 was almost totally inhibited by the Hsp-induced abortive mechanism, supporting previous data that this mechanism blocks phage DNA replication. Prf-induced abortive infection only partially (50%) inhibited capsid protein production, suggesting that this mechanism targets some other point, perhaps within transcription or translation processes. The results confirmed that Hsp and Prf act at different targets in the phage lytic cycle. Use of monoclonal antibodies also demonstrated that production of the major capsid protein is a nonlimiting step in the lytic cycle of lactococcal phage u136.

Evolution of a Lytic Bacteriophage via DNA Acquisition from the Lactococcus lactis Chromosome

We discovered a phage-host interaction in which the lytic phage ul36, in response to pressure exerted by an abortive phage resistance mechanism, acquired a large DNA fragment from the chromosome of Lactococcus lactis NCK203 to form a new phage, ul37. Phage ul37 was characterized at morphological, phenotypic, and genotypic levels and was found to be a member of the P335 species. Although it exhibits a high level of DNA homology with ul36, phage ul37 is resistant to the abortive mechanism and has a longer tail, a different base plate, and apparently a different origin of replication. The chromosomal DNA implicated in the formation of new phage ul37 was disrupted by site-specific integration in NCK203. This strategy prevented the appearance of ul37 during subsequent infections with ul36.

Closing lateral wedge valgus osteotomy with dynamic hip screw for the treatment of varus nonunion of pertrochanteric fracture: can restoration of biomechanics and stabilization alone heal?

INTRODUCTION

Nonunion of pertrochanteric fracture is rare and its occurrence especially without prior surgical intervention has been hardly ever reported. Hence there is not much literature describing the best way to treat them. Nonunion of pertrochanteric fracture collapses in to varus by virtue of deforming action of muscles and thus deranging the biomechanics of the hip and indirectly preventing fracture union further. Hence it is very important to re-orient the abductor lever arm to biomechanically advantageous normal configuration favoring fracture healing. In general, principles of treatment of nonunion like open reduction of the fracture with freshening of fracture fragments, stabilization and bone grafting are very difficult to the surgeon and the patient.

METHOD

We herewith describe for the first time in literature a prospective nonrandomized study of closing lateral wedge valgus intertrochanteric osteotomy in addition to dynamic hip screw osteosynthesis in the successful management of seven patients with varus trochanteric nonunion. Average operating time was 63 +/- 13 min (range 39-93 min) and blood loss was 212 +/- 32 ml (range 156-320 ml). Average pre-operative coxa vara of 94 degrees +/- 7 degrees (range 85 degrees -104 degrees ) had improved to a femoral neck shaft angle of 139 degrees +/- 4 degrees (range 134 degrees -145 degrees ) on postoperative radiographs.

RESULTS

All fractures and osteotomies had healed uneventfully at the last follow-up with good functional outcome. Harris Hip score had improved from 34 +/- 6 (range 22-47) to 89 +/- 4 (range 83-95) at an average of 11 months (range 7-13 months) follow-up. Valgus osteotomy converts shear forces across the fracture site into compressive forces thus achieving union.

Use of intramedullary fibular strut graft: a novel adjunct to plating in the treatment of osteoporotic humeral shaft nonunion

Humeral shaft fractures respond well to conservative treatment and unite without much problem. Since it is uncommon, there is not much discussion regarding the management of nonunion in the literature, and hence this is a challenge to the treating orthopaedic surgeon. Osteoporosis of the fractured bone and stiffness of the surrounding joints compounds the situation further. The Ilizarov fixator, locking compression plate, and vascularised fibular graft are viable options in this scenario but are technically demanding. We used a fibular strut graft for bridging the fracture site in order to enhance the pull-out strength of the screws of the dynamic compression plate. Six patients in the study had successful uneventful union of the fracture at the last follow-up. The fibula is easy to harvest and produces less graft site morbidity. None of the study patients needed additional iliac crest bone grafting. This is the largest reported series of patients with osteoporotic atrophic nonunion of humerus successfully treated solely using the combination of an intramedullary fibular strut graft and dynamic compression plate.

Plasma CRP level predicts left ventricular function and exercise capacity in patients with acute myocardial infarction

BACKGROUND

C-reactive protein estimation can help in predicting short- and long-term prognosis after acute myocardial infarction. High plasma C-reactive protein level in the acute phase strongly indicates a poor clinical outcome of the patients with myocardial infarction.

METHODS AND RESULTS

One hundred consecutive patients admitted with ST elevation myocardial infarction in the intensive coronary care unit in our hospital who were able to do symptom-limited treadmill test during early recovery phase were studied. Plasma C-reactive protein was measured at the time of admission by immunoturbidity method. The normal value of the C-reactive protein was taken as 0.8 mg/dl. Echocardiographic study was done on day three of admission and ejection fraction was estimated by modified Simpson's method. Symptom-limited treadmill exercise test was done in all the patients. Patients were classified into two groups based on level of C-reactive protein: those with low C-reactive protein level (1.26 +/- 0.91 mg/dl, n=40) and those with high C-reactive protein level (6.52 +/- 3.97 mg/dl, n=60). Ejection fraction was lower in high C-reactive protein group (46.7 +/- 11.9%) compared to low C-reactive protein group (56.9 +/- 7.7%) (p = 0.011). Exercise capacity was lower in high C-reactive protein group (2.8 +/- 1.4 METs) compared to low C-reactive protein group (5.5 +/- 2.5 METs) p = 0.027).

CONCLUSIONS

C-reactive protein levels are an index of the severity of myocardial necrosis which translate to worse left ventricular function. Higher the C-reactive protein level, lower the ejection fraction and worse may be the prognosis.

A rapid and improved method for the detection of Vibrio parahaemolyticus and Vibrio vulnificus strains grown on hydrophobic grid membrane filters

DNA probe-based detection methods were developed and characterized as an alternative to time-consuming and less specific conventional protocols. Digoxigenin-labeled probes were prepared by polymerase chain reaction amplification of the targeted sequences in the specific amplicons generated from genomic DNA. Specific probes with high yields were generated for the detection of the tlh gene of Vibrio parahaemolyticus and the cth gene of V. vulnificus. Colony (Southern) hybridization analyses were carried out using hydrophobic grid membrane filters (HGMFs) to allow biotype-specific differentiation of the two species. Eight strains of V. vulnificus and five strains of V. parahaemolyticus, including one standard (ATCC) strain of each biotype, were examined. Colony lysis, hybridization, and nonradioactive detection parameters were optimized for identification of the target biotypes arranged on the same HGMF and also on a conventional nylon membrane, thereby confirming the specificity of the probes and the comparative usefulness of the HGMFs. The experimental procedure presented here can be completed in 1 day. The protocol was designed specifically to identify the target Vibrio spp. and could potentially be used for the enumeration and differentiation of V. parahaemolyticus and V. vulnificus in foods.

Phaeohyphomycosis caused by Exophiala dermatitidis following intra-articular steroid injection

A patient with long-standing rheumatoid arthritis presented with a painful pigmented chronic nodule on the dorsum of the right hand, at the site of intra-articular steroid injections undertaken 5 years previously. Histology showed pigmented fungal elements consistent with phaeohyphomycosis. Cultures yielded black yeast-like colonies, identified as Exophiala dermatitidis and sensitive to itraconazole and amphotericin. A 1-month course of itraconazole resulted in marked clinical improvement but surgical excision and skin grafting were required for complete resolution. Phaeohyphomycosis has been related to inoculation injury but association with intra-articular steroid injection appears hitherto to be unreported.

Anti-DNA.RNA antibodies: an efficient tool for non-isotopic detection of Listeria species through a liquid-phase hybridization assay

This study was undertaken to evaluate the potential of a new approach using anti-DNA.RNA monoclonal antibodies to detect Listeria in both pure culture and inoculated meat and meat products. A sensitive liquid-phase assay was first developed, based on the formation in solution of a hybrid between a 784-bp DNA probe, specific for the genus Listeria, and target rRNA. Monoclonal antibody and antisera raised against hybrid nucleic acids were then used in various immunoenzymatic assays to detect specific hybrids formed in solution. System 2, using a double sandwich enzyme-linked immunosorbent assay, and system 1, using a biotinylated probe, proved to be very effective. The method using biotin-streptavidin complex, however, resulted in a higher background signal. System 2 described here, using unlabeled probe, was more effective. This strategy allowed the detection of as little as 2.5 pg target RNA from pure culture and 500 cells from inoculated meat homogenate, even in the presence of other contaminating bacteria. The assay was more sensitive and could be completed within 3 h, as opposed to several days when conventional culture methods were used.

Influence of Ammonium Salts and Cane Molasses on Growth of Alcaligenes eutrophus and Production of Polyhydroxybutyrate

The production of polyhydroxybutyrate (PHB) by Alcaligenes eutrophus DSM 545 was studied in a synthetic medium with 3% glucose at pH 7.0 supplemented with several ammonium substrates and cane molasses. Growth was measured by dry cell weight, and the PHB content was measured by gas chromatography. The effects of ammonium sources such as sulfate, nitrate, phosphate, and chloride salts and those of different ammonium sulfate concentrations were evaluated. The best growth and PHB production were obtained with ammonium sulfate; however, NH(inf4)(sup+) concentrations between 0.5 and 1.5 g/liter showed no significant difference. Ammonium sulfate was therefore used as the sole source of NH(inf4)(sup+) for experiments with cane molasses as the growth activator. Optimal growth and PHB production were obtained with 0.3% molasses. However, the yields of biomass (39 to 48%) and PHB (17 to 26%) varied significantly among the different ammonium substrates and cane molasses concentrations.

Biological inactivation of adhering Listeria monocytogenes by listeriaphages and a quaternary ammonium compound

The use of listeriaphages as a means of disinfecting contaminated stainless-steel and polypropylene surfaces was investigated. Surfaces artificially contaminated with L. monocytogenes 10401 and 8427 were sanitized with suspensions of listeriaphages (H387, H387-A, and 2671), all belonging to the Siphoviridae family. Phage suspensions at concentrations of up to 3.5 x 10(8) PFU/ml were at least as efficient as a 20 ppm solution of a quaternary ammonium compound (QUATAL) in reducing L. monocytogenes populations. A synergistic activity was observed when two or more phages were used in combination and when phages were suspended in QUATAL. The biological activity of the three phages was not affected by QUATAL concentrations of 50 ppm and a contact time of 4 h.

Production and characterization of anti-DNA-RNA monoclonal antibodies and their application in Listeria detection

Murine monoclonal antibodies (MAbs) specific for DNA-RNA hybrids were successfully produced with two different heteropolymers as antigens, cDNA-mRNA and phi X174 DNA-RNA heteroduplexes. The former was simpler to prepare. Both had shown similar immunogenicities. Two different immunoglobulin M MAbs were isolated. The 20D3 MAb, generated with the phi X174 DNA-RNA hybrid, showed association constants of 1.05 x 10(12), 2.12 x 10(10), and 1.68 x 10(7) for the antigens phi X174 DNA-RNA, cDNA-mRNA, and poly(rA)-poly(dT), respectively. The 6B5 MAb, obtained with the cDNA-mRNA hybrid, showed association constants of 1.59 x 10(5), 5 x 10(12), and 7.1 x 10(8) for the above-described antigens, respectively. With the 20D3 MAb, an immunoassay was developed for the detection of Listeria DNA-RNA hybrids. In brief, a biotinylated rRNA gene probe specific for the genus Listeria was hybridized with rRNA in the solution phase. The hybrids thus formed were then captured in microtiter plate wells precoated with the purified 20D3 MAb, and the probe-target hybrids were detected with a streptavidin-alkaline phosphatase conjugate. This assay was shown to be specific for the genus Listeria and highly sensitive, allowing the detection of as little as 2.5 pg of target rRNA.

A ribosomal DNA fragment of Listeria monocytogenes and its use as a genus-specific probe in an aqueous-phase hybridization assay

cDNAs were prepared from the total RNA of Listeria monocytogenes ATCC 19118 and used as probes to screen a genomic library of the same strain. Four clones were identified which contained ribosomal DNA fragments. Recombinant DNA from one of them was fractionated and differentially hybridized with the cDNA probes to RNA of L. monocytogenes and Kurthia zopfii. The resulting hybridization pattern revealed an HpaII fragment of 0.8 kb that was specific for the L. monocytogenes strain. The nucleotide sequence of this fragment showed 159 bases of the 3' end of the 16S rRNA gene, 243 bases of the spacer region, and 382 bases of the 5' end of the 23S rRNA gene. In dot blot hybridization assays, the 32P-labeled 784-bp fragment was specific only for Listeria species. Dot blot assays revealed that the 32P-labeled fragment can easily detect > or = 10 pg of total nucleic acids from pure cultures of L. monocytogenes, which corresponds to approximately 300 bacteria. This fragment was also used as a probe in an assay named the heteroduplex nucleic acid (HNA) enzyme-linked immunosorbent assay. In this system, the biotinylated DNA probe is hybridized in the aqueous phase with target RNA molecules and then specific HNAs are captured by HNA-specific antibodies. Captured HNA molecules are revealed with an enzyme conjugate of streptavidin. In a preliminary HNA enzyme-linked immunosorbent assay, the 784-bp fragment maintained its specificity for Listeria spp. and could detect 5 x 10(2) cells in artificially contaminated meat homogenate.

Production of Monoclonal Antibodies against the Major Capsid Protein of the Lactococcus Bacteriophage ul36 and Development of an Enzyme-Linked Immunosorbent Assay for Direct Phage Detection in Whey and Milk

The only major structural protein (35 kDa) of the lactococcal small isometric-headed bacteriophage ul36, a member of the P335 species, was isolated from a preparative sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Monoclonal antibodies (MAbs) were raised against the denatured 35-kDa protein. Six MAbs were selected and characterized. Western blots (immunoblots) showed that all MAbs recognized the 35 kDa but also a 45 kDa that is in lower concentration in the phage structure. Binding inhibition assays identified five families of MAbs that recognized nonoverlapping epitopes of the 35- and 45-kDa proteins. Immunoelectron microscopy showed that these two proteins are localized within the phage head, therefore indicating that the 35 kDa is a major capsid protein of ul36 and that the 45 kDa is a minor capsid protein. With two MAbs, a sandwich enzyme-linked immunosorbent assay (ELISA) was developed for direct detection of lactococcal phages in whey and milk samples. Whey and milk components, however, interfered with the conduct of the assay. Partial denaturation of milk samples by heat treatment in the presence of SDS and β-mercaptoethanol removed the masking effect and increased the sensitivity of the assay by 100-fold. With the method used here, 10 7 PFU/ml were detected by the ELISA within 2 h without any steps to enrich or isolate bacteriophages.

Purification of X-prolyl dipeptidyl aminopeptidase from Lactobacillus casei subspecies

Prolyl dipeptidylaminopeptidases from two subspecies of Lactobacillus casei were purified and biochemically characterized. L. casei ssp. casei UL21 (a debittering strain) and L. casei ssp. rhamnosus UL26 (a non-debittering strain) were the source bacteria for this study. Purification of the enzymes from both the sources was effected by a gel filtration step through Sephacryl S-300 followed by ion-exchange chromatography through DEAE Sephacel. This rendered an electrophoretically homogeneous enzyme preparation. The purified enzymes from both the sources showed similar temperature optimum (45 degrees C) and pH optimum (7.0). Their activity profiles on various substrates and the nature of inhibition by different inhibitors were also found to be similar, indicating that this enzyme is perhaps not significantly involved in the debittering process during the maturation of cheese.

Detection and activity of a bacteriocin produced by Leuconostoc mesenteroides

Leuconostoc mesenteroides UL5 was found to produce a bacteriocin, referred as mesenterocin 5, active against Listeria monocytogenes strains but with no effect on several useful lactic acid bacteria. The antimicrobial substance is a protein, since its activity was completely destroyed following protease (pronase) treatment. However, it was relatively heat stable (100 degrees C for 30 min) and partially denaturated by chloroform. The inhibitory effect of the bacteriocin on sensitive bacterial strains was determined by a critical-dilution micromethod. Mutants of L. mesenteroides UL5 which had lost the capacity to produce the bacteriocin were obtained. The mutant strain was stable and phenotypically identical to parental cells and remained resistant to the bacteriocin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to detect bacteriocin activity corresponding to an apparent molecular mass of about 4.5 kDa.

A rapid and efficient method of lysis of Listeria and other gram-positive bacteria using mutanolysin

A rapid and simple procedure is described for cell lysis for preparation of nucleic acids and intact ribosomal RNA from Gram-positive bacteria. Commercial mutanolysin (purified from Streptomyces globisporus) was used for inducing lysis. Listeria, Lactobacillus and Lactococcus strains were very sensitive to mutanolysin when compared to lysozyme. Susceptibility to mutanolysin was improved by a preliminary treatment with acetone, and sodium dodecyl sulfate reduced the efficiency of lysis when used together with mutanolysin. The procedure was also effective for recovering plasmids from these bacteria.

Effects of trichothecenes (T-2 toxin) on protein synthesis in vitro by brain polysomes and messenger RNA

The effects of T-2 toxin on protein synthesis were tested in two reticulocyte lysate in vitro systems pretreated with micrococcal nuclease. One of the test systems contained purified globin mRNA and was initiation dependent. The other contained rat brain polysomes and incorporated amino acids by an elongation dependent process. T-2 toxin inhibited the translation of globin mRNA at all concentrations tested, from 10(-8) M to 10(-4) M. Rat brain polysomes were much less sensitive to T-2 toxin than globin mRNA. While high concentrations of the toxin (10(-4) M) led to partial inhibition of protein synthesis by polysomes, low concentrations (10(-8) M and 10(-6) M) stimulated protein synthesis. Comparison of the above results with those obtained by other workers suggest that the T-2 toxin may inhibit not only the initiation step of translation, but also elongation and termination, depending upon the concentration of the toxin and the nature of the translation system. A similar mechanism may operate for all the trichothecene toxins that exert their effect through binding to ribosomal peptidyl transferase.

Purification of phosphofructokinase from rabbit skeletal muscle based on its ability to aggregate in absence of its effectors

Rabbit muscle phosphofructokinase was purified to homogeneity based on its property to form large aggregates with time at high concentration of its protein in absence of its effectors. The method involves no heat step or treatment with organic solvent or any ion-exchange columns. The enzyme thus prepared, however, exhibits the same kinetic properties as the enzyme purified by more drastic methods.

Perturbed angular correlation studies of 111In-labelled platelets

Indium-111, as the 8-hydroxyquinoline and acetylacetone complexes, has been used to label cellular blood components. Because of the gamma-ray cascade emitted following the decay of indium-111, perturbed angular correlation studies can be used to investigate the environment of the indium nucleus. Perturbed angular correlation studies have been carried out on the indium at various steps in the procedure used to label platelets with indium using both 8-hydroxyquinoline and acetylacetone as the ligand. Similar values of the integral correlation coefficient were obtained in both cases, suggesting identical labeling mechanisms. Following lysis of the platelets the values of (G22(infinity)) changed, suggesting that the intracellular complex is relatively weak.

An alternative pathway for the biosynthesis of isoprenoid compounds in bacteria

The pattern of incorporation of radioactivity from [1-14C]acetate and [2-14C]acetate into the polyprenyl side-chain of ubiquinones in bacteria (Azotobacter vinelandii, Pseudomonas sesami, Escherichia coli and Rhodopseudomonas capsulata) was studied. For this purpose, a new degradation method involving a modified Barbier-Wieland reaction of laevulinic acid was developed, and used along with the iodoform reaction. Both C-1 and C-2 of acetate were incorporated exclusively into C-2 of laevulinic acid suggesting that the well-known pathway through acetoacetyl-CoA ('acetoacetate pathway') was not operative in these bacteria. An alternative pathway ('acetolactate pathway'), starting with pyruvate and acetaldehyde as the distal precursors, and utilizing the reactions of leucine and valine metabolism, was postulated. It was also postulated that C-1 of acetate is incorporated not directly, but after oxidation to CO2. The pattern of incorporation of radioactivity from [U-14C]valine, [U-14C]alanine and NaH14CO3 into the side-chain of ubiquinone of R. capsulata was in agreement with the operation of the 'acetolactate pathway'.