Impact of COVID-19 lockdown on the atmospheric boundary layer and instability process over Indian region

The abrupt reduction in the human activities during the first lockdown of the COVID-19 pandemic created unprecedented changes in the background atmospheric conditions. Several studies reported the anthropogenic and air quality changes observed during the lockdown. However, no attempts are made to investigate the lockdown effects on the Atmospheric Boundary Layer (ABL) and background instability processes. In this study, we assess the lockdown impacts on the ABL altitude and instability parameters (Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CINE)) using WRF model simulations. Results showed a unique footprint of COVID-19 lockdown in all these parameters. Increase in the visibility, surface temperature and wind speed and decrease in relative humidity during the lockdown is noticed. However, these responses are not uniform throughout India and are significant in the inland compared to the coastal regions. The spatial variation of temperature (wind speed) and relative humidity shows an increase and decrease over the Indo Gangetic Plain (IGP) and central parts of India by 20% (100%) and 40%, respectively. Increase (80%) in the ABL altitude is larger over the IGP and central parts of India during lockdown of 2020 compared to similar time period in 2015-2019. This increase is attributed to the stronger insolation due to absence of anthropogenic activity and other background conditions. At the same time, CAPE decreased by 98% in the IGP and central parts of India, where it shows an increase in other parts of India. A prominent strengthening of CINE in the IGP and a weakening elsewhere is also noticed. These changes in CAPE and CINE are mainly attributed to the dearth of saturation in lower troposphere levels, which prevented the development of strong adiabatic ascent during the lockdown. These results provide a comprehensive observation and model-based insight for lockdown induced changes in the meteorological and thermo-dynamical parameters.

Is the atmospheric boundary layer altitude or the strong thermal inversions that control the vertical extent of aerosols?

It is well known that the atmospheric boundary layer (ABL) plays a significant role in controlling the variability of atmospheric constituents such as aerosols and trace-gases. Hence, significant diurnal and seasonal variation in these will be observed as the ABL altitude does. However, on several occasions, high aerosol concentration in the lidar measurements is observed even above the ABL altitude. This raised a question that up to what extent ABL altitude acts as a capping layer for these pollutants? From the detailed analysis carried out using long-term (2010-2018) lidar observations and simultaneous radiosonde profiles obtained from Gadanki, India, we show that 'there exist thermal inversions (TI), which are stronger than the ABL inversions, that fully control the vertical extent'. The detailed characteristics of TI (inversion strength (IS) and inversion depth (ID)) are also obtained. The results revealed that aerosol concentrations below the TI altitude increases with IS (ID) up to 3-4 K (300-400 m) during winter whereas in pre-monsoon it increases up to 2-3 K (100-200 m). Thus, IS of up to 2-4 K is required to fully trap the aerosol concentrations and this TI coincide with the ABL inversions for 51.7% only, particularly during the winter and pre-monsoon seasons. This analysis is further extended to different geographical locations of India using the aerosol profiles obtained from CALIPSO and a network of 23 radiosonde stations. The observed results provided further evidence that the vertical distribution of aerosols is restricted to the maximum extent by the TI but not the ABL altitude. These observations lead us to propose a hypothesis that 'trapping of aerosols fully occurs up to particular IS and ID only and the ABL altitude is not the deciding factor most of the time for capping the aerosol vertical distribution'. These findings will greatly help in modeling the diffusion and transport of air pollutants in the lower troposphere.

Historical and Projected Surface Temperature over India during the 20th and 21st century

Surface Temperature (ST) over India has increased by ~0.055 K/decade during 1860-2005 and follows the global warming trend. Here, the natural and external forcings (e.g., natural and anthropogenic) responsible for ST variability are studied from Coupled Model Inter-comparison phase 5 (CMIP5) models during the 20th century and projections during the 21st century along with seasonal variability. Greenhouse Gases (GHG) and Land Use (LU) are the major factors that gave rise to warming during the 20th century. Anthropogenic Aerosols (AA) have slowed down the warming rate. The CMIP5 projection over India shows a sharp increase in ST under Representative Concentration Pathways (RCP) 8.5 where it reaches a maximum of 5 K by the end of the 21st century. Under RCP2.6 emission scenarios, ST increases up to the year 2050 and decreases afterwards. The seasonal variability of ST during the 21st century shows significant increase during summer. Analysis of rare heat and cold events for 2080-2099 relative to a base period of 1986-2006 under RCP8.5 scenarios reveals that both are likely to increase substantially. However, by controlling the regional AA and LU change in India, a reduction in further warming over India region might be achieved.

Limitations of peritoneal lavage with antiseptics in prevention of recurrent colorectal cancer caused by tumor-cell seeding: experimental study in rats

PURPOSE

Exfoliated or soiled free malignant cells have serious consequences in patients undergoing gastrointestinal cancer surgery. The present study evaluates the toxicity and efficacy of cytotoxic agents in the prevention of cell seeding and tumor growth in the peritoneal cavity in an experimental model.

METHODS

Mtln3 adenocarcinoma cell viability was tested in vitro using the trypan blue exclusion test after incubation with povidone-iodine or chlorhexidine. In vivo, Fischer rats were inoculated with 10(5) or 10(6) cells followed by peritoneal lavage with physiological saline, chlorhexidine 0.02 percent, povidone-iodine low molecular weight 1 percent or povidone-iodine high molecular weight 1 and 2 percent in different quantities and incubation times.

RESULTS

Chlorhexidine 0.02 percent and povidone-iodine low molecular weight 1 percent or high molecular weight 2 percent, killed over 98 percent of 10(5) or 10(6) tumor cells in vitro. Povidone-iodine low molecular weight 1 percent and high molecular weight 2 percent were toxic and lethal when 5 ml were applied in the peritoneal cavity three times for five minutes. Chlorhexidine 0.02 percent applied after inoculation of 10(5) or 10(6) cells, reduced the tumor development only to 70 and 80 percent. Application of 5 ml povidone-iodine 1 percent low molecular weight or high molecular weight, three times for one and five minutes, after inoculation of 10(6) cells did not change the tumor take. However, inhibition of Mtln3 cells to form metastases was observed. When povidone-iodine low molecular weight 1 percent was used three times for one minute after 10(5) tumor cells were "soiled", no toxicity was observed and the tumor take was reduced to 30 percent (P < 0.05).

CONCLUSIONS

Povidone-iodine toxicity proved to be a major issue in vivo. However, povidone-iodine low molecular weight 1 percent was safe when used for short periods and very effective when a limited number of tumor cells was inoculated. The use of cytotoxic agents to prevent recurrent disease caused by tumor cell seeding in patients seems to make sense only when the "inoculum size" of exfoliated or soiled cancer cells is limited.

Prevention of anastomotic tumour take by on-table colon washout with povidone-iodine. an experimental study in rats

The presence of organic material in the intestinal lumen is reported to interfere with the efficacy of cancericidals when used in low concentrations to prevent anastomotic recurrence in colorectal cancer surgery. We aimed at investigating the efficacy of intra-operative whole-colon washout using povidone-iodine in an experimental model of anastomotic tumour growth. A large inoculum of highly 'tumorigenic' carcinoma cells was instilled in the colonic lumen of Fischer rats. The whole-colon water washout was intended to remove the luminal organic material. This was followed by irrigation of increasing concentrations of povidone-iodine up to 5% with or without additional incubation for 10-20 min. Five animals died after 30 min incubation with povidone-iodine 5%. Tumour take was observed in all control animals including after irrigation with physiological saline. Increasing the povidone-iodine concentration from 1 to 5% reduced the rate of tumour take, but not significantly. The anastomotic tumour growth was significantly reduced after tumour cell inoculation followed by whole-colon lavage and luminal incubation for 20 min with povidone-iodine 5%. Application of intra-operative whole-colon washout to remove the luminal 'organic material' followed by luminal application of povidone-iodine 5% for a sufficient incubation time could reduce the risk of anastomotic recurrence in colorectal cancer surgery.

Infradiaphragmatic central venous pressures reflect supradiaphragmatic pressures in stable burn patients

OBJECTIVE

Because the skin of the groin is often spared, femoral central venous catheters are sometimes used in patients with extensive burns. The accuracy of central venous pressures obtained from the infradiaphragmatic location relative to the traditional supradiaphragmatic value is not known in this population.

METHODS

Seventeen seriously injured but hemodynamically stable burn patients were enrolled in a protocol approved by the human studies committee in which, during scheduled central venous line rotations, supradiaphragmatic and infradiaphragmatic central venous pressures were determined simultaneously.

RESULTS

These 17 patients were an average of 21.8+/-20.1 years old (range, 6 months to 61 years), and the average burn size was 60.8+/-22.6% (range, 20 to 90%). Supradiaphragmatic and infradiaphragmatic pressures correlated well, with an r value of 0.903, p less than 0.01.

CONCLUSION

In the absence of clinically significant abdominal distention, infradiaphragmatic central venous pressure is an accurate reflection of supradiaphragmatic pressure, and indirectly, circulating blood volume.

Percutaneous endoscopic gastrostomy in burn patients

BACKGROUND

Prolonged enteral feedings are required occasionally in seriously burned individuals. We have employed percutaneous endoscopic gastrostomy (PEG) in selected patients who require particularly prolonged access, thus prompting this review.

METHODS

The PEG procedure was performed under general anesthesia in combination with another surgical procedure using a variety of commercially available needle and guidewire kits in 14 patients.

RESULTS

These 14 patients had an average age of 55.2 +/- 6.6 years and a burn involving 38 +/- 8% of the body surface. Eleven of these patients had suffered an inhalation injury. The tubes were placed an average of 57 +/- 10.5 days after injury through unburned and unharvested skin in four patients (28%), healed donor sites in five patients (35%), healed burn in one patient (1%), and grafted burn in four patients (28%). One patient, whose catheter was placed through a grafted fascial excision, developed moderate local wound erosion. Tubes were known to have been left in place as long as 155 days. However, most were removed in rehabilitation hospitals, and we were unable to determine how long most were left in place. We are unaware of any problems with the tubes occurring after discharge from the acute care setting.

CONCLUSIONS

In selected patients, PEG can provide more comfortable access for prolonged enteral feedings than nasogastric tubes and can be placed with minimal morbidity.

Local and systemic effects of intraoperative whole-colon washout with 5 per cent povidone-iodine

BACKGROUND

Segmental intraluminal instillation of several tumoricidal agents including povidone-iodine has been advocated to prevent anastomotic recurrence after colonic resection for colorectal cancer. The local and systemic effects of on-table whole-colon washout using 5 per cent povidone-iodine were assessed in patients undergoing elective surgery for colorectal cancer.

METHODS

The local effect of 5 per cent povidone-iodine on the colonic mucosa and the effect of colonic mucosal damage by povidone-iodine on tumour take was first investigated in Fischer 344 rats. In 12 euthyroid non-allergic patients, on-table whole-colon lavage via the appendix was performed. Systemic (thyroid function) and local (mucosal damage assessed by repeat biopsies) effects were studied, as well as the in vitro tumoricidal effect of the final anal effluent on tumour cell suspensions.

RESULTS

After 30 min of contact with povidone-iodine the rat colonic mucosa was severely injured, with detachment of the epithelial cell layer. Povidone-iodine-induced 'colitis' did not result in tumour development after inoculation of 10(6) Mtln3 carcinoma cells in ten rats. Epithelial desquamation was also observed, in all but one patient, 1 and 4 h after colonic lavage. However, epithelial restitution started within 1 day and no abnormality was revealed after 3-7 days. Urinary iodine excretion increased markedly and was not within normal values after 1 week. Levels of thyroid hormones decreased significantly but became normal within 1 week. The anal effluent containing povidone-iodine was found to be tumoricidal in vitro on a human colonic carcinoma cell line and on a tumour cell suspension produced from the patient's tumour.

CONCLUSION

On-table whole-colon washout using 5 per cent povidone-iodine seems clinically feasible. This technique deserves further study as a substitute for preoperative bowel preparation and may help to prevent recurrent cancer due to implantation of viable exfoliated tumour cells.

Influence of blood components and faeces on the in vitro cancericidal activity of povidone-iodine

BACKGROUND

Tumoricidal agents have been used to kill viable exfoliated tumour cells following colorectal cancer surgery. Recent in vivo experiments have thrown some doubt on the tumoricidal activity of povidone-iodine.

METHODS

The cytotoxic effect of distilled water and of povidone-iodine at 0.04, 0.4, 0.8, 2 and 4 per cent final concentrations on human SW620 colonic cancer cells in the presence of red blood cells, purified haemoglobin and red blood cell (RBC) membranes, plasma, albumin, faeces and bacteria was investigated. Cell viability was assessed using the trypan blue assay and MTT test.

RESULTS

The presence of albumin and plasma decreased the tumoricidal activity of povidone-iodine except for the highest concentration tested. Bacterial suspension did not influence the efficacy of povidone-iodine. Faecal material was found to have an intrinsic tumoricidal effect. Both intact and lysed RBCs very strongly inhibited the tumoricidal activity of all povidone-iodine concentrations tested. This inhibitory effect was due to haemoglobin, but not to RBC membranes.

CONCLUSIONS

Low concentrations of povidone-iodine fail to kill all 'exfoliated' cancer cells in the presence of proteins, intact or lysed RBCs. Therefore, washing out of these organic materials before application of a relatively high povidone-iodine concentration (e.g. 5 per cent or greater) may be more useful in killing viable exfoliated tumour cells during surgery for colorectal cancer.

Tumor cell implantation after colonoscopy with biopsies in a patient with rectal cancer: report of a case

PURPOSE

Colonoscopy with biopsy(ies) is performed in patients with colorectal cancer for diagnosis and screening of synchronous lesions. There is some fear of spreading the disease related to implantation of tumor cells at sites of mucosal damage or to hematogenous or lymphatic spread as a result of tumor manipulation.

METHODS

A total colonoscopy including biopsies, performed in a patient because of anal blood loss and tenesmus, revealed a circular, polypoid, ulcerated mass from 1.5 to 12 cm above the anal verge. After preoperative radiotherapy, the patient was subjected to surgical intervention.

RESULTS

Histopathology revealed a poorly differentiated rectum adenocarcinoma, staged pT4N1Mx. At approximately 12 cm proximally from the tumor, a biopsy taken through a minute irregularity of the mucosa revealed some granulation tissue with adjacent normal colon mucosa. The basis of this granulation tissue, corresponding to submucosa, contained poorly differentiated tumor elements.

CONCLUSIONS

This tiny lesion might have been caused by implantation of exfoliated cancer cells in a biopsy site. It may not be without risk to create excessive biopsy lesions in the presence of a manifestly malignant tumor because of the possibility of tumor cell implantation.

Tumoricidal activity of antiseptics with assessment of cell viability in mice with severe combined immunodeficiency

Previously, we have assessed the efficacy of different cytotoxic agents on the viability of SW620 human colonic carcinoma cells in vitro. In this study, we have investigated the tumoricidal efficacy of some antiseptic agents on SW620 human colonic carcinoma cells which were subsequently inoculated into severe combined immunodeficient (SCID) mice. An inoculum of 5 x 10(6) cells suspended in 200 microliters buffer solution was found to be the minimum number of cells needed to result in tumour growth within 8 weeks after subcutaneous injection into SCID mice. The integrity of the cells was assessed in vitro with the trypan blue exclusion test after 30 min incubation in distilled water (DW), chloramine 0.5% in DW and polyvinyl pyrrolidone iodine (PVP-I) 0.01, 0.05, 0.1 and 5% in DW. DW and PVP-I 0.01% were not tumoricidal, neither in vitro nor in vivo. In contrast, PVP-I 5% and chloramine 0.5% 'killed' all or almost all tumour cells in vitro and prevented their growth in vivo. PVP-I 0.05 and 0.1% were less effective in vitro than 5%, but could prevent in vivo proliferation unless an adjustment of the residual number of viable tumour cells was performed. These data indicate the importance of the amount of the tumour inoculum and hence the need to use a maximally effective 'killing' agent.

Exfoliated tumour cells and locally recurrent colorectal cancer

The presence of intraluminal viable exfoliated tumour cells has been demonstrated in patients with colorectal cancer. Several non-randomised studies found a significant reduction of the recurrence rate after the intraoperative luminal instillation of cytotoxic agents, as compared with "historical" patient series. Antiseptic solutions, e.g. sodium hypochlorite and povidone-iodine, were reported to be "cancericidal" for exfoliated cancer cells in vitro. A survey held among Belgian surgeons practising colorectal cancer surgery revealed that 78% of them never use any agent during surgery. Only a minority performs pre-resectional luminal instillation-mostly to treat the distal (low) anastomotic level: 14% in patients with rectal cancer and 7% in patients with colon cancer. About 8% of the surgeons only perform peritoneal/pelvic lavage at the end of the procedure. This is in strong contrast with surgical practice in the UK. It seems reasonable to advocate intra-operative pre-resectional bowel washouts with cytotoxic agents besides other measures to avoid recurrence, e.g. the no touch isolation technique with early division of the vascular supply, wide excision of the mesenterium, avoidance of iatrogenic tumour perforation, "en bloc" resection if adjacent organs are invaded, adjuvant radio- and chemotherapy.

Comparative study of classical, colorimetric and immunologic staining methods for the assessment of tumor cell viability

The trypan blue exclusion test, the MTT test and an immunostaining test for apoptosis were performed before and after incubation of SW620 human colonic carcinoma cells with different cytotoxic agents (CTAs) in order to assess tumor cell viability and CTA efficacy in vitro. A modified MTT test using light microscopy was also performed. A good correlation was found between the trypan blue assay and the MTT test, as determined by spectrophotometry. There was no 'overestimation' of cell viability as measured by the trypan blue test. The monitoring of formazan formation by light microscopy was feasible, but not very reliable since it did not show a good correlation with findings determined by spectrophotometry. The apoptosis test failed to show good correlation with other tests. Distilled water had no relevant cytotoxic effect, while chlorhexidine cetrimide (HAC 3.5%), chloramine 0.5% and polyvinylpyrrolidone iodine (PVP-I) > or = 0.05% damaged a large majority of cells. PVP-I at a concentration of > or = 5% was found to be the most effective CTA.

Planimetry study of the percent of body surface represented by the hand and palm: sizing irregular burns is more accurately done with the palm

Sizing irregular burns is commonly done with use of the patient's hand as a template representing 1% of the body surface. To verify that this is accurate over a broad range of ages or to see if the surface of the palm is a more consistent template, a planimetry study was done. This revealed that the surface area of the palm averaged 0.52% total body surface area (+/- 0.07) and the palmar surface of the hand 0.85% total body surface area (+/- 0.08). The surface of the palm was a more consistent template and represented 0.5% of the body surface over a broad range of ages.

Clinical experience with the use of biodegradable tacks in pediatric patients with burns

Stainless steel staples are very popular for securing grafts and dressings on patients with burns because of the speed and security with which they can be applied and the fact that stainless steel is nonreactive. In patients with large burns hundreds of staples are used and can be difficult to visualize and remove; they are therefore retained. Although stainless steel does not cause local tissue reaction, its presence can confuse the later evaluation of local pain. A new biodegradable tack has been developed. We describe an initial experience with this device in pediatric patients with burns and make suggestions regarding their use.