Activated Ras/JNK driven Dilp8 in imaginal discs adversely affects organismal homeostasis during early pupal stage in Drosophila,a new checkpoint for development

Background

Dilp8-mediated inhibition of ecdysone synthesis and pupation in holometabolous insects maintains developmental homeostasis through stringent control of timing and strength of molting signals. We examined reasons for normal pupation but early pupal death observed in certain cases.

Results

Overexpression of activated Ras in developing eye/wing discs inhibited Ptth expression in brain via upregulated JNK signaling mediated Dilp8 secretion from imaginal discs, which inhibited ecdysone synthesis in prothoracic gland after pupariation, leading to death of ~25- to 30-hour-old pupae. Inhibition of elevated Ras signaling completely rescued early pupal death while post-pupation administration of ecdysone to organisms with elevated Ras signaling in eye discs partially rescued their early pupal death. Unlike the earlier known Dilp8 action in delaying pupation, hyperactivated Ras mediated elevation of pJNK signaling in imaginal discs caused Dilp8 secretion after pupariation. Ectopic expression of certain other transgene causing pupal lethality similarly enhanced pJNK and early pupal Dilp8 levels. Suboptimal ecdysone levels after 8 hours of pupation prevented the early pupal metamorphic changes and caused organismal death.

Conclusions

Our results reveal early pupal stage as a novel Dilp8 mediated post-pupariation checkpoint and provide further evidence for interorgan signaling during development, wherein a peripheral tissue influences the CNS driven endocrine function.

     

Comparative cytological study of lymph node tuberculosis in HIV-infected individuals and in patients with diabetes in a developing country

Tuberculosis (TB) is a common infection affecting patients with human immunodeficiency virus (HIV) and diabetes mellitus (DM). With the increasing incidence of HIV infection and DM in a developing country like India, TB is definitely on the rise. In a given population, one expects to see these three diseases in varying combinations, such as HIV and TB, DM and TB, HIV and DM with TB. In such combinations TB may lack the characteristic clinical and histological picture due to the associated depressed cell-mediated immunity seen in both diseases and TB may have an unusual clinical presentation and cytology picture. In this retrospective study of 36 months, from January 1997 to December 1999, 109 cases diagnosed cytologically as tuberculous lymphadenitis and tested for HIV infection and investigated as well for DM were selected. Forty-six (42%) were nondiabetic HIV patients, 13 (12%) were non-HIV DM patients, and 50 (46%) had TB without HIV infection or DM. The coexistence of both HIV and DM was not noted. The cytomorphological characteristics supplemented by culture studies of each of these three groups were compared in detail and based on these four cytological patterns, Pattern 1, Pattern 2, Pattern 3, and Pattern 4 emerged and were characterized. This study highlights the usefulness of cytomorphology of the lymph nodes to characterize the cytopathological profile of TB in both HIV and DM, which have many clinical and immunological similarities, and indirectly postulate the extent of immune suppression and evolve effective strategies in the management of coexisting diseases. Such a comparative study has not been carried out in the past.     

The rising trend of invasive zygomycosis in patients with uncontrolled diabetes mellitus.

Zygomycosis is an emerging infection worldwide. A study was conducted to understand its spectrum in the Indian scenario. All patients diagnosed for invasive zygomycosis at a tertiary care center in north India from 2000-2004, were retrospectively analyzed. A total of 178 cases (mean average of 35.6 cases/year) of zygomycosis were diagnosed. Rhino-orbito-cerebral type (54.5%) was the commonest presentation followed by cutaneous (14.6%), disseminated (9.0%), and gastrointestinal (8.4%) zygomycosis. Renal and pulmonary zygomycosis were seen in 6.7% patients each. Uncontrolled diabetes mellitus (in 73.6% of cases) was the significant risk factor in all types (Odds Ratio 1.5-8.0) except renal zygomycosis. Breach of skin was the risk factor in 46.2% patients with cutaneous zygomycosis. However, no risk factor could be detected in 11.8% patients. Antemortem diagnosis was possible in 83.7% cases. The commonest (61.5%) isolate was Rhizopus oryzae followed by Apophysomyces elegans in 27% patients. Combination of debridement surgery and amphotericin B therapy was significantly better in survival of the patients (P<0.005) than amphotericin B alone (79.6% vs. 51.7% survival). Thus, a rising trend of invasive zygomycosis was observed in patients with uncontrolled diabetes mellitus in India. Consistent diagnosis of renal zygomycosis in apparently healthy hosts and the emergence of A. elegans in India demand further study.     

Collaborative study of antibiotic medium 3 and flow cytometry for identification of amphotericin B-resistant Candida isolates

Center 1 used the National Committee for Clinical Laboratory Standards M27-A2 method and antibiotic medium 3 (AM3) test to determine amphotericin B resistance in 5 of 30 Candida isolates. These isolates were tested at center 2 by AM3 test and flow cytometry (FC). The agreements (C1-C2) were 90% for AM3 test and FC and 73% for the AM3 tests.     

Procalcitonin: “To Follow or Not to Follow” That's the Question

How to cite this article: Todi SK. Procalcitonin: “To Follow or Not to Follow” That''s the Question. Indian J Crit Care Med 2021;25(5):484–485.

Sepsis has been recognized as an important cause of mortality globally, more so in resource-limited regions.¹ It accounts for 19.7% of all global deaths. Timely antibiotic therapy in patients with septic shock is associated with a significant decrease in mortality in observational studies.² Though this has not been uniformly noted in patients with sepsis without shock. Moreover, empirical use of appropriate antibiotic therapy has also been associated with a significant decrease in infection-related and all-cause mortality in critically ill patients.³ This has led to a widespread use of early broad-spectrum antibiotics in patients with septic shock. Unfortunately, despite the lack of robust evidence, similar practice is usually followed in patients with infection without organ dysfunction or shock. This has resulted in the emergence of multidrug-resistant (MDR) bacterial infections not only in hospitals but also in the community, which leads to a vicious cycle of prescribing further empirical broad-spectrum antibiotics for a new infection especially hospital-acquired. In the absence of a reliable method to “rule in” or “rule out” infection, it will be difficult to curb the upfront use of antibiotics. Decreasing antibiotic burden in the intensive care unit (ICU) and in the individual patient will be possible by sending appropriate microbiological cultures and deescalating antibiotics wherever possible and to decrease the duration of antibiotic therapy. As cultures are often negative and may only yield colonizing organisms, the scope of de-escalation may be limited especially in settings with MDR infection with limited options for de-escalation. Shortening the duration of antibiotics without compromising the efficacy may be the only way to achieve the goal of decreasing antibiotic exposure. Assessment of clinical improvement is the current prevalent practice of deciding on the duration of antibiotic therapy. This practice is based predominantly on a subjective assessment, which has led to a widely variable practice of antibiotic duration, which on an average is longer than what is probably desirable. Utilizing biomarkers like Procalcitonin has been recommended for decreasing the duration of antibiotic therapy.⁴To discuss the impact of a biomarker on the duration of antibiotic therapy, one needs to ascertain what should be an “ideal” duration of therapy. This will depend on multiple factors, with some situations requiring “prolonged” therapy like immunosuppressed state, the severity of infection (debatable), sites of infection like endocarditis, and microbiological factors like staphylococcal bacteremia and MDR gram-negative infection. Even in these situations exact duration of therapy is arbitrary and is dependent on the clinical response of the patient. On the other hand, in most other situations duration of antibiotic therapy may be “shorter”. The current practice of prescribing antibiotics for a certain minimum number of days, usually seven days is not based on sound evidence. There is a growing literature of evidence that the duration of antibiotic therapy can be shortened even further in most infections including severe infection. Recent trials in intra-abdominal infections requiring surgery have compared four days of antibiotics with seven days and have found equivalent results.⁵ The generalizability of these results is not possible in many situations and also clinical trials on the duration of antibiotic therapy are not available for many infections encountered in clinical practice in ICU. It is evident that the duration of antibiotic therapy requires individualization and is a field where personalized medicine can be readily practiced. Procalcitonin is the biomarker most commonly studied in this regard. Earlier studies on procalcitonin use in various infectious diseases had shown a decrease in duration of antibiotic therapy without any harmful effect with the use of this biomarker. This was achieved by serially measuring procalcitonin values and stopping the antibiotic when the level came below a certain percentage of baseline (usually 80%) or below a certain cutoff value usually less than 0.5 µg/mL. Relapse of infection was not noticed in these trials, with some trials even showing a decrease in mortality.⁶ Thus, the use of procalcitonin was recommended in sepsis guidelines to decrease the duration of antibiotic therapy.In a study published this issue, the author randomized 90 patients (45 in each arm) admitted with sepsis/septic shock to a procalcitonin-guided duration of antibiotic therapy or institutional protocol-based therapy. Procalcitonin value of <0.1 µg/mL was taken as the cut-off for stopping antibiotic therapy. Clinical response was also considered in both arms while considering the duration of antibiotic therapy. Patients requiring a short course of therapy like elective surgery or prolonged course of therapy like endocarditis, immunocompromised patients were excluded from the study. Duration of antibiotic therapy was significantly shorter in the procalcitonin group of 5 days vs 8 days in the control group. ICU length of stay, duration of mechanical ventilation, and duration of inotrope requirement were also significantly higher in the control group. Secondary infection defined as the occurrence of a new infection at another site was significantly higher in the control group, probably due to longer ICU stay and longer duration of mechanical ventilation. Reinfection rate which was defined as recurrence of infection at the same site was similar in both the group and also there were no significant differences in mortality between the groups. There were baseline differences in the groups, with septic shock patients being significantly higher in the control group, though the severity of score markers like SOFA and APACHE II and lactate levels were surprisingly similar between the two groups and bacteremia was more common in the procalcitonin group, which could be due to less robust randomization due to small sample size. Historically, clinicians are reluctant to shorten the duration of therapy in patients with sepsis and septic shock, which leads to prolonged antibiotic therapy and the authors should be commended to undertake this study in the septic shock population. Despite limitations, this study emphasizes the scope of safely decreasing the duration of antibiotic therapy in these groups of patients.Similar to the present study most of the studies on duration of antibiotic therapy have used clinical response along with procalcitonin levels to adjudicate duration of antibiotic justifying shortening the duration only in patients with positive clinical response. In practice, “positive clinical response” is an not all-or-none phenomenon with various parameters like fever, leukocytosis showing favorable or unfavorable trends that might be concordant or discordant and the composite response assessment remains a subjective impression. Moreover, the duration of antibiotic therapy in the control arm in many studies on procalcitonin has been of more than seven days duration which is contrary to the present evidence of shorter duration even in a sicker group of patients. Studies comparing the use of procalcitonin where the control arm had a shorter duration of antibiotic have not yielded significant results. The use of the procalcitonin strategy in infections with MDR organisms or immunosuppressed patients has also not been well studied as these were excluded from many procalcitonin studies. Despite these limitations, the current trend of prescribing a longer duration of antibiotics can only be curbed by judicious use of biomarkers like procalcitonin along with antibiotic stewardship practices. In the absence of a willingness to shorten the duration of antibiotics based on the procalcitonin result, the utility of this biomarker will not be realized. Moreover, the need for serial measurement of this expensive test also adds to the cost of care in ICU. Future research agenda on the utility of procalcitonin would be to compare this molecule with a relatively inexpensive biomarker like C-reactive protein on decreasing duration of therapy and total antibiotic burden in a critically ill patient with sepsis and septic shock and its effect on other important clinical and economic parameters like resource utilization, secondary bacterial and fungal infection, incidence of MDR bacterial infection and Clostridium difficle infection. This should be achieved without increasing the incidence of relapse or reinfection. The utility of the use of this biomarker in patients infected with MDR infection or immunosuppressed patients also needs to be studied. It might even be prudent to study the negative impact of the use of this molecule which may lead to unnecessary prolongation of antibiotic duration in patients who have clinically responded but not yet reached the procalcitonin cutoff. The control arm duration of antibiotic therapy in procalcitonin should be shorter in accordance with the recent guidelines. Approach to the duration of antibiotic therapy in patients with initial norma procalcitonin values and what should be the ideal frequency of repeating this marker need also be studied. Last but not the least, compliance with antibiotic stewardship practices of deescalating or stopping antibiotic based on a protocolized algorithm of procalcitonin value need to be studied in critically ill patient population.⁷     

Evidence of linkage and association on 18p11.2 for psychosis.

The genetic basis of bipolar disorder (BPD) and schizophrenia (SCZ) has been established through numerous clinical and molecular studies. Although often considered separate nosological entities, evidence now suggests that the two syndromes may share some genetic liability. Recent studies have used a composite phenotype (psychosis) that includes BPD, SCZ, psychosis not otherwise specified, and schizoaffective disorder, to identify shared susceptibility loci. Several chromosomal regions are reported to be shared between these syndromes (18p, 6q, 10p, 13q, 22q). As a part of our endeavor to scan these regions, we report a positive linkage and association finding at 18p11.2 for psychosis. Two-point linkage analysis performed on a series of 52 multiplex pedigrees with 23 polymorphic markers yielded a LOD score of 2.02 at D18S37. An independent set of 159 parent offspring trios was used to confirm this suggestive finding. The TDT analysis yielded support for association between the marker D18S453 and the disease allele (chi2 = 4.829, P < 0.028). This region has been implicated by several studies on BPD [Sjoholt et al. (2004); Mol Psychiatry 9(6):621-629; Washizuka et al. (2004); Biol Psychiatry 56(7):483-489; Pickard et al. (2005); Psychiatr Genet 15(1):37-44], SCZ [Kikuchi et al. (2003); J Med Dent Sci 50(3):225-229; Babovic-Vuksanovic et al. (2004); Am J Med Genet 124(3):318-322] and also as a shared region between the two diseases [Ishiguro et al. (2001); J Neural Transm 108(7):849-854; Reyes et al. (2002); Mol Psychiatry 7(4):337-339; Craddock et al. (2005); J Med Genet 42(3):193-204]. Our findings provide an independent validation of the above reports, and suggest the presence of susceptibility loci for psychoses in this region.     

Diblock Copolymers Based on 1,4‐Dioxan‐2‐one and ε‐Caprolactone: Characterization and Thermal Properties

Summary: Various poly(ε‐caprolactone‐block‐1,4‐dioxan‐2‐one) (P(CL‐block‐PDX)) block copolymers were prepared according to the living/controlled ring‐opening polymerization (ROP) of 1,4‐dioxan‐2‐one (PDX) as initiated by in situ generated ω‐aluminium alkoxides poly(ε‐caprolactone) (PCL) chains in toluene at 25 °C. 1 ¹H NMR, PCS and TEM measurements have attested for the formation of colloids attributed to a growing PPDX core surrounded by a solvating PCL shell during the polymerization of PDX promoted by ω‐Al alkoxide PCL chains in toluene. The thermal behavior of the P(CL‐block‐PDX) copolymers was studied by DSC; showing two distinct melting temperatures (as well as two glass transition temperatures) similar to those of the respective homopolyesters. Finally, the thermal degradation of the P(CL‐block‐PDX) block copolymers was investigated by TGA simultaneously coupled to a FT‐IR spectrometer and a mass spectrometer for evolved gas analysis (EGA). The degradation occurred in two consecutive steps involving a first unzipping depolymerization of the PPDX blocks followed by the degradation of the PCL blocks via both ester pyrolysis and unzipping reactions.

TEM observation of P(CL‐block‐PDX) block copolyesters ( = 11 600 and = 22 100) as formed by vaporization starting from a diluted suspension in toluene/TCE mixture solvent (50/50 v/v).     

Asbestos exposure in lung carcinoma: a necropsy-based study of 414 cases.

BACKGROUND: The prerequisites necessary for attributing lung carcinoma to asbestos, represent a controversial issue. METHODS: Three parameters (occupational history, pleural plaques, and lung asbestos bodies) were investigated in 414 consecutive cases of lung carcinoma, examined at necropsy at the Hospital of Monfalcone, Italy. Occupational data were obtained from the patients' relatives by personal or telephone interviews. Pleural plaques were classified into three classes (small, moderate, large). Routine lung sections were examined for asbestos bodies in all cases; isolation and counting were performed in 408 cases. RESULTS: The series included 353 men, and 61 women, aged between 38 and 97 years. The male patients had worked in industries in 74% of cases (60% in shipbuilding). Men showed pleural plaques in 82% of cases (moderate or large plaques in 58.7%). Asbestos bodies were observed in routine lung sections in 34.8%, and in 31% exceeded the value of 5,000 bodies per gram of dried tissue. Among women the principal features were: history or domestic exposure to asbestos in 36% of the cases, prevalence of pleural plaques 34% (moderate or large plaques 15%), asbestos bodies in routine lung sections in 3.3% and there was no case with an asbestos body burden over 5,000/g. The fraction of asbestos-related carcinomas among male patients varied between 24.7 and 61%, depending on the criteria used for attribution. CONCLUSIONS: Different criteria indicated about 60% of the present lung carcinomas among men as plausibly attributable to asbestos.