Assessing the clinical efficacy of low-volume therapeutic plasma exchange in achieving recovery from acute liver failure induced by yellow phosphorous poisoning

BACKGROUND

Acute liver failure (ALF) following yellow phosphorous (YP) ingestion is similar to acetaminophen-induced ALF and it has become a public concern in our region. This study assessed low volume therapeutic plasma exchange (LV-TPE) efficacy in improving the transplant free survival in YP poisoning.

METHODS

Adult patients with toxicology reports of YP and ALF requiring critical care were included in the study. LV-TPE was planned for three consecutive days and three more if required. Performed 1.3 to 1.5 plasma volume replacing with 0.9% normal saline, 5% human albumin solution, and fresh frozen plasma based on ASFA 2019 criteria. MELD score, laboratory parameters, LV-TPE details were captured. The study end point was clinical outcome of the patients.

RESULTS

Among 36 patients, 19 underwent LV-TPE and 17 opted out of LV-TPE and they were included as a control arm. The MELD score was 32.64 ± 8.05 and 37.83 ± 9.37 in both groups. There were 13 survivors in LV-TPE group leading to a 68.42% reduction in mortality. The coagulation and biochemical parameters showed a significant percentage change after LV-TPE. Refractory shock, delay in initiating procedure and acidosis were independent predictors of mortality.

CONCLUSION

A well-timed LV-TPE improves the survival of patients with ALF due to YP poisoning.

An Observational Study of Nutritional Assessment, Prescription, Practices, and Its Outcome among Critically Ill Patients Admitted to an Intensive Care Unit

Aim and background

Optimal feeding strategy for critically ill patients of intensive care unit (ICU) is often a matter of debate as patients admitted to ICU are highly catabolic and reduction in muscle mass is very common. We aimed at early achievement of nutritional goals in preventing skeletal muscle breakdown and improving clinical outcomes among critically ill patients with high risk of malnutrition.

Materials and methods

Nutrition risk in the critically ill (mNUTRIC) Score was used to identify the risk of malnutrition within 24 hours of admission. Quadriceps muscle mass index was measured within 24 hours of admission to ICU and repeated on 7th day. Enteral feeding was monitored by the nutrition expert as part of routine patient care and clinical outcomes were monitored.

Results

A total of 287 patients admitted in ICU were screened for malnutrition and 60 (20.9%) of them had high score (>5). There was no statistically significant reduction in the quadriceps muscle mass index (p < 0.05) (t = 0.601) measured within 24 hours of admission and on the 7th day of ICU stay, signifying that the nutritional prescription and monitoring may be useful in preserving the muscle mass. This study did not find statistically significant association between the high mNUTRIC score on admission and the clinical outcomes, such as 28 days mortality, incidence of pressure ulcers, length of ICU stay, and hospital-acquired infection (p > 0.05).

Conclusion

Early initiation and maintenance of enteral nutrition is essential for meeting target calories and protein requirements. It may help to preserve muscle mass in critically ill patients who are otherwise at high risk of malnutrition.

How to cite this article

Sharon T, Nayak SG, Shanbhag V, Hebbar S. An Observational Study of Nutritional Assessment, Prescription, Practices, and Its Outcome among Critically Ill Patients Admitted to an Intensive Care Unit. Indian J Crit Care Med 2024;28(4):364-368.

Palliative and end-of-life care practices for critically ill patients and their families in a peri-intensive care setting: A protocol for an umbrella review

OBJECTIVES

This umbrella review will summarize palliative and end-of-life care practices in peri-intensive care settings by reviewing systematic reviews in intensive care unit (ICU) settings. Evidence suggests that integrating palliative care into ICU management, initiating conversations about care goals, and providing psychological and emotional support can significantly enhance patient and family outcomes.

METHODS

The Joanna Briggs Institute (JBI) methodology for umbrella reviews will be followed. The search will be carried out from inception until 30 September 2023 in the following databases: Cochrane Library, SCOPUS, Web of Science, CINAHL Complete, Medline, EMBASE, and PsycINFO. Two reviewers will independently conduct screening, data extraction, and quality assessment, and to resolve conflicts, adding a third reviewer will facilitate the consensus-building process. The quality assessment will be carried out using the JBI Critical Appraisal Checklist. The review findings will be reported per the guidelines outlined in the Preferred Reporting Items for Overviews of Reviews statement.

RESULTS

This umbrella review seeks to inform future research and practice in critical care medicine, helping to ensure that end-of-life care interventions are optimized to meet the needs of critically ill patients and their families.

Changes in Driving Pressure vs Oxygenation as Predictor of Mortality in Moderate to Severe Acute Respiratory Distress Syndrome Patients Receiving Prone Position Ventilation

Background

Prone position ventilation (PPV) causes improvement in oxygenation, nevertheless, mortality in severe acute respiratory distress syndrome (ARDS) remains high. The changes in the driving pressure (DP) and its role in predicting mortality in moderate to severe ARDS patients receiving PPV is unexplored.

Methods

A prospective observational study, conducted between September 2020 and February 2023 on moderate-severe ARDS patients requiring PPV. The values of DP and oxygenation (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen [PaO2/FiO2]) before, during, and after PPV were recorded. The aim was to compare the DP and oxygenation before, during and after PPV sessions among moderate- severe ARDS patients, and determine the best predictor of mortality.

Results

Total of 52 patients were included; 28-day mortality was 57%. Among the survivors, DP prior to PPV as compared to post-PPV session reduced significantly, from 16.36 ± 2.57 cmH2O to 13.91 ± 1.74 cmH2O (p-value < 0.001), whereas DP did not reduce in the non-survivors (19.43 ± 3.16 to 19.70 ± 3.15 cmH2O (p-value = 0.318)]. Significant improvement in PaO2/FiO2 before PPV to post-PPV among both the survivors [92.75 [67.5-117.75]) to [205.50 (116.25-244.50)], (p-value < 0.001) and also among the non-survivors [87.90 (67.75-100.75)] to [112 (88.00-146.50)], (p-value < 0.001) was noted. Logistic regression analysis showed DP after PPV session as best predictor of mortality (p-value = 0.044) and its AUROC to predict mortality was 0.939, cut-off ≥16 cmH2O, 90% sensitivity, 82% specificity. The Kaplan-Meier curve of DP after PPV ≥16 cmH2O and <16 cmH2O was significant (Log-rank Mantel-Cox p-value < 0.001).

Conclusion

Prone position ventilation-induced decrease in DP is prognostic marker of survival than the increase in PaO2/FiO2. There is a primacy of DP, rather than oxygenation, in predicting mortality in moderate-severe ARDS. Post-PPV session DP ≥16 cmH2O was an independent predictor of mortality.

How to cite this article

Todur P, Nileshwar A, Chaudhuri S, Shanbhag V, Cherisma C. Changes in Driving Pressure vs Oxygenation as Predictor of Mortality in Moderate to Severe Acute Respiratory Distress Syndrome Patients Receiving Prone Position Ventilation. Indian J Crit Care Med 2024;28(2):134-140.

Development and Internal Validation of a Novel Prognostic Score to Predict Mortality in Acute Respiratory Distress Syndrome - Driving Pressure, Oxygenation and Nutritional Evaluation - "DRONE Score"

Introduction

There are few scores for mortality prediction in acute respiratory distress syndrome (ARDS) incorporating comprehensive ventilatory, acute physiological, organ dysfunction, oxygenation, and nutritional parameters. This study aims to determine the risk factors of ARDS mortality from the above-mentioned parameters at 48 h of invasive mechanical ventilation (IMV), which are feasible across most intensive care unit settings.

Methods

Prospective, observational, single-center study with 150 patients with ARDS defined by Berlin definition, receiving IMV with lung protective strategy.

Results

Our study had a mortality of 41.3% (62/150). We developed a 9-point novel prediction score, the driving pressure oxygenation and nutritional evaluation (DRONE) score comprising of driving pressure (DP), oxygenation accessed by the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) ratio and nutritional evaluation using the modified nutrition risk in the critically ill (mNUTRIC) score. Each component of the DRONE score with the cutoff value to predict mortality was assigned a particular score (the lowest DP within 48 h in a patient being always ≥15 cmH2O a score of 2, the highest achievable PaO2/FiO2 <208 was assigned a score of 4 and the mNUTRIC score ≥4 was assigned a score of (3). We obtained the DRONE score ≥4, area under the curve 0.860 to predict mortality. Cox regression for the DRONE score >4 was highly associated with mortality (P < 0.001, hazard ratio 5.43, 95% confidence interval [2.94-10.047]). Internal validation was done by bootstrap analysis. The clinical utility of the DRONE score ≥4 was assessed by Kaplan-Meier curve which showed significance.

Conclusions

The DRONE score ≥4 could be a reliable predictor of mortality at 48 h in ARDS patients receiving IMV.

Impact of Diabetes in COVID-19 Associated Mucormycosis and its Management: A Non-Systematic Literature Review

BACKGROUND

COVID-19 has become extremely dangerous manifesting itself in a variety of forms ranging from a simple flu-like illness to death. COVID-19 associated mucormycosis (CAM) is a global threat with diabetes being a major contributor.

OBJECTIVE

This review aims to give a clear picture of the impact of hyperglycemia in CAM along with its management.

METHODS

Google and Google Scholar were searched and studies that addressed the impact of diabetes in CAM were considered for this review. We also performed a bibliographic search of the specific article to find additional studies.

RESULTS

A series of events such as unregulated activation of innate immune system modification, pro-inflammatory M1 macrophages activation, and the depletion of natural killer cell activity is very common in patients with COVID-19. In addition, the exacerbated cytokine syndrome and hyperinflammatory response may elevate the severity of this condition, which further leads to higher mortality. The impaired immune phase which follows provide the niche for increased infection among diabetic patients making them more prone towards developing mucormycosis and associated infections. Early detection, surgical debridement, and appropriate medical treatment with antifungals and hypoglycaemic agents may help control the infection and associated morbidity and mortality. COVID-19 drugs, hypoglycaemic agents, antifungals, and comorbidities have all been associated with adverse side effects and drug interactions.

CONCLUSION

Clinicians should be well aware of this deadly disease and manage COVID-19, diabetes, and mucormycosis through individualized treatment regimens to improve patient outcomes.

Epidemiology of sepsis and risk factors for mortality in intensive care unit: a hospital based prospective study in South India

OBJECTIVE

The present study was aimed at elucidating the epidemiology of sepsis, with a special emphasis on identifying the common bacterial aetiology, proportion of infections caused by multi-drug resistant (MDR) bacteria, and risk factors associated with 28-day mortality at a university hospital in South India.

METHODS

A prospective study was undertaken from January 2017 to March 2018. Adult patients with the diagnosis of sepsis requiring intensive care unit (ICU) care were recruited. Baseline clinical, epidemiological, and laboratory data were recorded, and their association with 28-day mortality was assessed using logistic regression models.

RESULTS

400 subjects with a qSOFA score ≥2 at the time of ICU admission were included in the study. The mean age was 55.7 ± 16.6 years, and 69% were males. The mean SOFA score at the time of admission was 9.9 ± 2.7. Bacterial aetiology of sepsis was established in 53.5% of cases and 24% were caused by MDR pathogens. Carbapenem resistance was observed in 37% of the Gram-negative isolates. Escherichia coli (34.1%) was the leading pathogen. Overall, the 28-day mortality in ICU was 40%. 38% died within 48 h of ICU admission. Hypertension and SOFA > 9, male gender, and baseline-creatinine values >2.4 mg/dl were risk factors for mortality.

CONCLUSIONS

Male gender, hypertension, SOFA > 9, and increased creatinine were identified as the predictors for mortality. Infectious aetiology remained undetected in nearly half of the cases using routine microbiology culture methods. Mortality within the first 48 h of admission to ICU is high and prompts the need for increasing awareness about early sepsis diagnosis in community health care settings.

COVID-19 in kidney transplant recipients; an Indian experience

Introduction: Kidney transplant recipients appear to be at high risk for severe COVID-19 illness due to chronic immunosuppression and coexisting conditions. Objectives: We aimed to study the clinical characteristics, laboratory and radiological results, treatment aspects and clinical outcomes of kidney transplant patients with COVID-19. Patient and Methods: Twenty consecutive kidney transplant patients with COVID-19 pneumonia from two tertiary care centers from India were retrospectively studied from July 1 to Oct 31, 2020. Results: Of 20 patients, 18 required admission; mean age was 42.8±9.39 years and 18 out of 20 (90%) were male. Symptom onset to testing time was a mean of 3.05±1.47 days. All patients were on triple immunosuppression. The median time since transplantation to COVID-19 was 3.75 years (IQR 2.37-5.41). Fever, cough and breathlessness were the most common presenting symptoms. Nine out of twenty (45%) had severe COVID-19 while six out of 20 (30%) required intensive care. Twelve (60%) patients had lymphopenia. Additionally mycophenolate was withheld in seventeen out of twenty (85 %) and enoxaparin and intravenous methylprednisolone were administered in all hospitalized patients while remdesivir was prescribed in 16 out of 20 (80%). Moreover, acute kidney injury (AKI) was seen in five out of 20 (25%) since one of died (5%). After a median hospital stay of 8.5 days (IQR 6.75-15.5), seventeen patients were discharged from the hospital. Conclusion: COVID-19 infection in kidney transplant recipients is usually a moderate-severe form. COVID-19 should be a differential diagnosis for fever in this high-risk population however lymphopenia may not be seen in all. Antimetabolite withdrawal, intravenous steroid, anticoagulation and early remdesivir were all found to be safe and effective strategies for improving outcomes. Early diagnosis and timely treatment may decrease mortality in this high-risk population.

Factors affecting the outcomes in patients with acute respiratory distress syndrome in a tertiary care setting

Purpose

The clinical profile and factors affecting outcomes in acute respiratory distress syndrome (ARDS) from adequately sample-sized Indian studies are still lacking. We aimed to investigate the clinical profile, treatment pattern, outcomes; and to assess factors affecting non-recovery in ARDS patients.

Patients and methods

A retrospective observational study was conducted among adult ARDS patients admitted during five year period (January 2014-December 2018) in a South Indian tertiary care setting. The relevant data were collected from the medical records to the data collection form. The univariate and multivariate logistic regression analyses were conducted to identify the predictors of outcomes using SPSS v20.

Results

A total of 857 participants including 496 males and 361 females with a mean age of 46.86 ± 15.81 years were included in this study. Fever (70.9%), crepitation (58.3%), breathlessness (56.9%), and cough (45%) were the major clinical presentation. Hypertension (25.2%), kidney disease (23.8%), and diabetes (22.3%) were the major comorbidities; and sepsis (37.6%), pneumonia (33.3%), and septic shock (27.5%) were the major etiological factors observed. Antibiotics and steroids were administered to 97.9% and 52.3% of the population, respectively. The recovery rate was 47.49%. The patients with scrub typhus, dengue, pancreatitis, and oxygen supplementation had significantly lower mortality. The factors such as advanced age, sepsis, septic shock, liver diseases, and ventilation requirements were observed to be the independent predictors of non-recovery in ARDS patients.

Conclusion

A comparable recovery rate was observed in our population. Advanced age, sepsis, septic shock, liver diseases, and ventilation requirements were the independent predictors of non-recovery.

Utility of Age-adjusted Charlson Comorbidity Index as a Predictor of Need for Invasive Mechanical Ventilation, Length of Hospital Stay, and Survival in COVID-19 Patients

Background

Multiple parameters may be used to prognosticate coronavirus disease-2019 (COVID-19) patients, which are often expensive laboratory or radiological investigations. We evaluated the utility of age-adjusted Charlson comorbidity index (CCI) as a predictor of outcome in COVID-19 patients treated with remdesivir.

Materials and methods

This was a single-center, retrospective study on 126 COVID-19 patients treated with remdesivir. The age-adjusted CCI, length of hospital stay (LOS), need for invasive mechanical ventilation (IMV), and survival were recorded.

Results

The mean and standard deviation (SD) of age-adjusted CCI were 3.37 and 2.186, respectively. Eighty-six patients (70.5%) had age-adjusted CCI ≤4, and 36 (29.5%) had age-adjusted CCI >4. Among patients with age-adjusted CCI ≤4, 20 (23.3%) required IMV, whereas in those with age-adjusted CCI >4, 19 (52.8%) required IMV (p <0.05, Pearson's chi-square test). In those with age-adjusted CCI ≤4, the mortality was 18.6%, whereas it was 41.7% in patients with age-adjusted CCI >4 (p <0.05, Pearson's chi-square test). The receiver operating curve (ROC) of age-adjusted CCI for predicting the mortality had an area under the curve (AUC) of 0.709, p = 0.001, and sensitivity 68%, specificity 62%, and 95% confidence interval (CI) [0.608, 0.810], for a cutoff score >4. The ROC for age-adjusted CCI for predicting the need for IMV had an AUC of 0.696, p = 0.001, and sensitivity 67%, specificity 63%, and 95% CI [0.594, 0.797], for a cutoff score >4. ROC for age-adjusted CCI as a predictor of prolonged LOS (≥14 days) was insignificant.

Conclusion

In COVID-19 patients, the age-adjusted CCI is an independent predictor of the need for IMV (score >4) and mortality (score >4) but is not useful to predict LOS (CTRI/2020/11/029266).

How to cite this article

Shanbhag V, Arjun NR, Chaudhuri S, Pandey AK. Utility of Age-adjusted Charlson Comorbidity Index as a Predictor of Need for Invasive Mechanical Ventilation, Length of Hospital Stay, and Survival in COVID-19 Patients. Indian J Crit Care Med 2021;25(9):987-991.

Efficacy and safety of corticosteroids in acute respiratory distress syndrome: An overview of meta-analyses

BACKGROUND

Evidence-based recommendations on the efficacy and safety of corticosteroids in acute respiratory distress syndrome (ARDS) remain a therapeutic challenge. Findings from several systematic reviews and meta-analyses are inconsistent. We aimed to assess the published meta-analyses through a systematic review approach and provide further insight into the current uncertainty and also to perform an updated meta-analysis from all the available primary studies.

METHODOLOGY

We followed the Preferred Reporting Items for Systematic Review (PRISMA) guidelines to establish the patients, intervention, control and outcome (PICO) for reviewing published meta-analyses. Data sources such as PubMed/MEDLINE, SCOPUS, Cochrane and Google Scholar from inception to February 2021 were accessed. Prevention of ARDS, mortality, ventilator-free days, ICU stay and safety in terms of occurrence of adverse effects were the patient-related outcomes. The review also assessed meta-analysis design-related outcomes which includes the quality of meta-analysis, factors contributing to the risk of bias, extent and sources of heterogeneity, publication bias and robustness of findings. AMSTAR-2 checklist assessed the quality of published meta-analyses.

RESULTS

A total of 18 meta-analyses were reviewed comprising a total of 38 primary studies and 3760 patients. Fourteen studies were in ARDS, three in community-acquired pneumonia and one in critical care. The overall quality of meta-analyses was observed to be critically low to high. A non-significant risk of publication bias and non-significant level of heterogeneity was observed in the reviewed meta-analysis. Corticosteroid was significantly effective in preventing ARDS among CAP patients. The effect of corticosteroids on mortality was observed to be still inconsistent, whereas significant improvement was observed with ICU and ventilator outcomes compared with the control group. Our meta-analysis observed a significant reduction of mortality in RCTs (RR: 0.78; 95% CI: 0.61 to 0.99) and the duration of mechanical ventilation (MD: -4.75; 95% CI: -7.63 to -1.88); and a significant increase in ventilator-free days (MD: 6.03; 95% CI: 3.59 to 8.47) and ICU-free days (MD: 8.04; 95% CI: 2.70 to 13.38) in ARDS patients treated with corticosteroids compared with the control group.

CONCLUSION

The quality of included studies ranged from critically low to high demonstrating inconsistency in risk of bias. While older studies found no significant effect, recent meta-analyses of RCTs found a significant mortality reduction in the corticosteroid group with considerable levels of heterogeneity. The updated meta-analysis by our team found a significant reduction in mortality in the pooled estimation of RCTs but not in cohort studies. Corticosteroid therapy was effective in terms of ICU and ventilator outcomes with minimal safety concerns. Future meta-analyses should be well executed with specific research questions and well performed with minimal risk of bias to produce good quality evidence.

COVID-19 Palliative and End-of-Life Care Plan: Development and Audit of Outcomes

Objectives:

Palliative care (PC) referral in serious and critical COVID-19 improves decision-making, health resource utilisation, end-of-life symptom management and family support. In this study, we explored developing a systematic decision-making matrix for PC referral in COVID-19 and audited its outcomes.

Materials and Methods:

A team of interdisciplinary experts developed a hospital COVID-19 PC plan. PC referral and outcomes of PC referral in hospitalised COVID-19 patients were audited.

Results:

Out of 1575 inpatients, 1066 (67.7%) had mild and 509 (32.3%) had serious and critical COVID-19 illness. Among 50 (3.1%) referred to PC, 5 (0.4%) had mild and 45 (8.8%) had serious and critical COVID-19 illness. Out of 45 serious and critical COVID-19 patients referred to PC, 38 (84%) received end-of-life care (EOLC), 4 (9%) self-discharged against medical advice and 3 (7%) recovered. Forty-seven (94%) were referred for goals-of-care discussion. About 78% received opioids, 70% benzodiazepines and 42% haloperidol for symptom management. Among 45 serious and critical COVID-19 patients referred to PC, foregoing life-sustaining treatment was documented in 43 (96%) but implemented only in 23 (53%). Out of 38 who received EOLC, ICU was the place of death in 31 (82%) and ward in 7 (18%).

Conclusion:

Despite interdisciplinary experts developing a hospital COVID-19 PC, low referral of serious and critical COVID-19 patients to PC was observed. PC referral enabled access to management of end-of-life symptoms and facilitated limitation of life-sustaining treatment in some COVID-19 patients with serious illness. Educating critical care physicians about the scope of PC in the COVID-19 setting might improve PC referral.

Paraquat: The Poison Potion

Paraquat is a commonly used herbicide in India that has lethal consequences even on minimal consumption. The case fatality rate for this poisoning is high and there is dearth of evidence-based recommendation for the treatment of this poison. This review article explores the diagnosis and management of paraquat poisoning with an emphasis on recent advances in treatment. Though immunosuppressants and antioxidants are conventionally used, there is a gap in evidence to prove survival benefit of these treatment regimens. There are also some data showing the use of hemoperfusion (with toxin-specific cartridges) as an early intervention, i.e., within 4 hours of exposure to the poison. The recent drug, Edaravone, has also shown promise in the prevention of renal and hepatic injury in paraquat poisoning. Though it did not reduce pulmonary fibrosis in patients with paraquat poisoning, it delays the generation and development of pulmonary fibrosis. However, there is a need for more clinical and experimental studies to validate its use in paraquat poisoning.

HOW TO CITE THIS ARTICLE

Sukumar CA, Shanbhag V, Shastry AB. Paraquat: The Poison Potion. Indian J Crit Care Med 2019;23(Suppl 4):S263-S266.

Scaphoid fracture non-union: a systematic review of surgical treatment using bone graft

This systematic review assesses the quality and outcomes of published articles concerning bone graft surgery for scaphoid fracture non-union. Searches of the CENTRAL, MEDLINE, EMBASE, CINAHL and AMED databases captured 2710 articles. Each article was screened and 144 met our inclusion criteria. Data regarding source, study design, population, intervention, comparator and outcomes were extracted. There were 5464 scaphoid non-union outcomes within the 144 studies. Mean reported union rates for vascularized and non-vascularized bone graft were 84% and 80%, respectively. Avascular necrosis was diagnosed in several ways and, when present, the vascularized bone graft union rate was 74% compared with 62% with non-vascularized bone graft. Reported union rates vary considerably. These differences may be due to patient factors, fracture factors, treatment factors or study design failures or bias. We recommend that future researchers take into account the deficiencies of previous studies and use the suggested minimum data set in future studies.

LEVEL OF EVIDENCE

II.

Toxicological profile of aureofungin: a potent plant antifungal antibiotic

Aureofungin is a heptaene type of antifungal antibiotic used for controlling plant fungal infections and diseases, during pre and post harvesting period of various crops. Acute and subacute oral toxicity of aureofungin in rats was studied along with haematological, urine analysis and other biochemical parameters related to liver and kidney organ functions. The results of these studies indicate mild toxic symptoms at higher doses which were reversible following its withdrawal.

Genotoxicity assessment of the antifungal antibiotic aureofungin in Salmonella typhimurium and Swiss albino mice

The widely used agricultural antifungal agent aureofungin (ARF) was subjected to genotoxicity assessment using the Ames Salmonella assay as well as the in vivo micronucleus test and dominant lethal test in Swiss mice. In the Ames Salmonella spot test, ARF slightly elevated the number of histidine revertants after metabolic activation over a wide dose range (1-1000 micrograms/plate) in TA102 but not in TA97a, TA98 or TA100. In the preincubation plate incorporation assay with TA102, ARF increased the number of revertants in a dose-dependent manner only after metabolic activation. ARF failed to significantly elevate the frequency of micronucleated polychromatic erythrocytes (PE) in the bone marrow of Swiss mice. It elevated the frequency of dominant lethal mutations in the 7th and 8th weeks at 30 mg/kg body weight, a concentration much higher than the actual concentration used in the field. We conclude that ARF is non-mutagenic in somatic cells in vivo at doses used in the present study, probably mutagenic in stem-cell spermatogonia and may be classified as an equivocal promutagen, possibly acting as a cross-linker.

Differences in hydrophobic properties for human alpha 2-macroglobulin and pregnancy zone protein as studied by affinity phase partitioning

Human alpha 2-macroglobulin and pregnancy zone protein are related with regard to primary structure, physicochemical properties, and quarternary structure. Both proteins undergo conformational changes when they form complexes with proteinases or react with primary amines. The surface properties of the native, chymotrypsin-treated and methylamine-treated forms of alpha 2-macroglobulin and pregnancy zone protein were studied by partitioning in aqueous two-phase systems composed of 7.5% dextran T70 and 5% poly(ethylene glycol) 8000. All proteins and their derivatives had a high potential for hydrophobic interaction as analyzed in terms of affinity for poly(ethylene glycol) esters of fatty acids included in the phase systems. Treatment of alpha 2-macroglobulin with methylamine or chymotrypsin increased the surface hydrophobicity significantly compared to that of the native protein. No difference in hydrophobic interaction was found for native and methylamine-treated pregnancy zone protein, but the chymotrypsin-treated protein showed a marked increase in binding to the hydrophobic ligand. The changes in surface hydrophobicity parallel changes in receptor binding properties of the derivatized forms of alpha 2-macroglobulin and could be a signal for binding to cell-surface receptors, followed by internalization.

Calculation of free and bound fractions of testosterone and estradiol-17 beta to human plasma proteins at body temperature

A mathematical model for the calculation of free and protein bound concentrations of testosterone and estradiol in plasma is presented. The method is based on the knowledge of the total concentrations of all steroids competing for the same binding site on testosterone-estradiol-binding globulin (TeBG), the concentration of albumin, the binding capacity of TeBG, and the association constants of the steroids to the two binding proteins. For the calculations we have determined the total concentrations of testosterone and estradiol. TeBG binding capacity, albumin concentration and the association constants for the binding of testosterone, estradiol and 5 alpha-dihydrotestosterone (DHT) to TeBG and albumin at 37 degrees C. Physiological concentrations of some androgen metabolites reported in the literature were also included in the calculations, namely: DHT, 5-androstene-3 beta, 17 beta-diol (Ae) and 5 alpha-androstane-3 alpha, 17 beta-diol (Aa). The binding constants for Ae and Aa to TeBG and albumin were also from the literature. Mean values of testosterone were calculated for 11 normal men and expressed as percentages of total: 2.0% was unbound, 53--55% bound to albumin and 43--45% bound to TeBG. For 16 normal women of a fertile age the corresponding values were 1.5%, 36--37% and 62%. For estradiol they were 2.4% 68--70% and 28--30% in the men and 2.0%, 52% and 45--46% in the women. Variations in the concentrations of DHT. Ae and Aa did not influence the free concentrations of testosterone and estradiol to any significant extent. It was furthermore concluded that the androgen metabolites could be omitted from the calculations without affecting the calculated concentrations.

Needle aspiration of metastatic melanoma

Needle aspiration of nodal and extranodal metastases of malignant melanoma was evaluated in 74 patients. All patients had the initial diagnosis of malignant melanoma established on surgical biopsy and histologic sections. A 20-cc glass syringe and an 18-gauge needle were used, and the material obtained was stained by the Wright-Giemsa technique. Adequate material was obtained, and a cytologic diagnosis of malignant melanoma was made in 67 patients (90.5%). In seven patients (9.5%) the specimens contained nondiagnostic material. The diversity of cell types, cytoplasm staining affinity and pigmentation is described. Despite the high variability of the cytologic features encountered, malignant melanoma usually can be diagnosed on cytologic smears. Difficulties in recognizing the nonpigmented varieties are emphasized. The procedure was well tolerated, and no complications were seen.

Protein-protein interactions studied by counter-current distribution. I. Theoretical computations

Many biological macromolecules are known to interact either with themselves, with other macromolecules or with small compounds. A simple equilibrium method for detecting and quantifying these interactions is to study the mutual influence of the molecules on their respective counter-current distribution in liquid-liquid biphasic systems. The theoretical counter-current distribution patterns for the components in an interacting system, A + B in equilibrium AB, have been calculated for two models in order to establish the boundary conditions and to optimize the experimental procedure. The patterns have been calculated for a range of association constants, partition coefficients and initial concentrations of the two reactants.