Recent advances in the in vitro and in vivo methods to assess impact of P-glycoprotein and breast cancer resistance protein transporters in central nervous system drug disposition

One challenge in central nervous system (CNS) drug discovery has been ensuring the blood-brain barrier (BBB) penetration of compounds at an efficacious concentration that provides suitable safety margins for clinical investigation. Research providing for the accurate prediction of brain penetration of compounds during preclinical discovery is important to a CNS program. In the BBB, P-glycoprotein (P-gp) (ABCB1) and breast cancer resistance protein (BCRP) (ABCG2) transporters have been demonstrated to play a major role in the active efflux of endogenous compounds and xenobiotics out of the brain microvessel cells and back to the systemic circulation. In the past 10 years, there has been significant technological improvement in the sensitivity of quantitative proteomics methods, in vivo imaging, in vitro methods of organoid and microphysiological systems, as well as in silico quantitative physiological based pharmacokinetic and systems pharmacology models. Scientists continually leverage these advancements to interrogate the distribution of compounds in the CNS which may also show signals of substrate specificity of P-gp and/or BCRP. These methods have shown promise toward predicting and quantifying the unbound concentration(s) within the brain relevant for efficacy or safety. In this review, the authors have summarized the in vivo, in vitro, and proteomics advancements toward understanding the contribution of P-gp and/or BCRP in restricting the entry of compounds to the CNS of either healthy or special populations. Special emphasis has been provided on recent investigations on the application of a proteomics-informed approach to predict steady-state drug concentrations in the brain. Moreover, future perspectives regarding the role of these transporters in newer modalities are discussed.

Cystinosis: Status of research and treatment in India and the world

Cystinosis is an autosomally inherited rare genetic disorder in which cystine accumulates in the lysosome. The defect arises from a mutation in the lysosomal efflux pump, cystinosin (or CTNS). Despite the disease being known for more than a century, research, diagnosis, and treatment in India have been very minimal. In recent years, however, some research on cystinosis has been carried out on understanding the pathophysiology and in the development of a humanized yeast model for interrogating the CTNS protein. There has also been a greater awareness of the disease that has been facilitated by the formation of the Cystinosis Foundation of India just over a decade ago. Awareness among primary physicians is critical for early diagnosis, which in turn is critical for proper treatment. Eight different mutations have been observed in cystinosis patients in India, and the mutation spectrum seems different to what has been seen in the US and Europe. Despite these positive developments, there are immense hurdles still to be surmounted. This includes ensuring that the diagnosis is done sooner, making cysteamine more easily available, and, also for the future, to make accessible the promise of gene therapy to cystinosis patients.

Impact of the COVID-19 pandemic on the management of surgical patients presenting in an emergency setting -Report from a tertiary referral centre

Introduction:

At the onset of the first wave of COVID-19 pandemic, the publications on managing surgical emergencies were sparse. Health care personnel were facing an unprecedented problem with limited information. On this background, we have reviewed the operational challenges faced and the protocols followed by us while managing emergency surgical patients. The clinical presentations, RT-PCR testing rates, trend of COVID-19 positivity in emergency surgical patients and its comparison to the general population, swab positivity among screen positive and negative patients, grade of COVID-19 affection, the outcomes in emergency surgical patients, and COVID-19 affection in treating personnel is studied.

Patients and Methods:

A protocol for triaging patients at presentation into screen positive or negative for COVID-19 was instituted. A proforma for all admitted patients over the period of March 2020 to August 2020 was maintained. A retrospective review of this data was carried out after Institutional Ethics Committee permission.

Results:

A total of 222 patients presented to the surgical emergency, of which 110 required admission. Of the admitted patients, 28 were COVID-19 positive. The positivity amongst admitted and operated patients increased to 50% and 66.67%, respectively in August. The difference in mortality rate amongst the operated COVID-19 positive (11.1%) and negative (14.28%) patients was nonsignificant. None of the treating doctors had to be quarantined during this period.

Conclusions:

The number of COVID-19 positive patients rose serially over the study period. The outcome was not affected by the COVID-19 status in mild cases. A high rate of COVID-19 positivity was seen in patients requiring emergency surgery. Universal precautions ensured delivering treatment to emergency patients in standard time. Testing should continue for all as screening alone is not effective as the virus spreads into the population. Proper protocols helped us to protect the health care workers.

Early presentation of ruptured post-traumatic hepatic artery pseudoaneurysm

Visceral artery aneurysms (VAA) are an uncommon but well recognized condition. Hepatic artery aneurysms (HAA) represent 14-20% of all visceral artery aneurysms. Post traumatic hepatic artery pseudoaneurysm is an uncommon delayed complication of blunt liver trauma. Here we present a case of a 27 year old male with blunt abdominal trauma who developed a post traumatic pseudoaneurysm of the hepatic artery just proximal to its bifurcation into the left and right branches. The pseudoaneurysm ruptured within 12 hours of injury and he required double ligation of the hepatic artery as well as right and left hepatic arteries. However, the bleeding continued through the retrograde flow from the gastroduodenal artery and hence, ligation of gastrodudenal artery was also done. The decision of complete devasularisation of liver was taken as an emergency lifesaving procedure. The patient recovered and was discharged without sequel.

A Genetic Screen for Investigating the Human Lysosomal CystineTransporter, Cystinosin

Cystinosin, a lysosomal transporter is involved in the efflux of cystine from the lysosome to the cytosol. Mutations in the human cystinosin gene (CTNS) cause cystinosis, a recessive autosomal disorder. Studies on cystinosin have been limited by the absence of a robust genetic screen. In the present study we have developed a dual strategy for evaluating cystinosin function that is amenable to rapid genetic analysis. We show that human cystinosin expressed in this yeast confers growth on cystine when the protein is mistargeted to the plasma membrane by the deletion of the C-terminal targeting signal, GYQDL. We also screened a vacuolar protein sorting deletion library, and subsequently created multiple vps deletion mutants for kinetic studies. The double deletion, vps1Δvps17Δ, greatly enhanced uptake. This enabled validation by kinetic studies, including first studies on the WT CTNS protein (that contained the GYQDL motif). Using this screen we isolated several gain of function mutants, G131S/D, G309S/D, A137V, G197R, S270T, L274F and S312N showing enhanced growth on low concentrations of cystine. Kinetic analysis yielded insights into the role of the residues (including one of the patient mutations, G197R). The results indicate that the screen could be effectively used for interrogating and understanding the CTNS protein.

Thiol trapping and metabolic redistribution of sulfur metabolites enable cells to overcome cysteine overload

Cysteine is an essential requirement in living organisms. However, due to its reactive thiol side chain, elevated levels of intracellular cysteine can be toxic and therefore need to be rapidly eliminated from the cellular milieu. In mammals and many other organisms, excess cysteine is believed to be primarily eliminated by the cysteine dioxygenase dependent oxidative degradation of cysteine, followed by the removal of the oxidative products. However, other mechanisms of tackling excess cysteine are also likely to exist, but have not thus far been explored. In this study, we use Saccharomyces cerevisiae, which naturally lacks a cysteine dioxygenase, to investigate mechanisms for tackling cysteine overload. Overexpressing the high affinity cysteine transporter, YCT1, enabled yeast cells to rapidly accumulate high levels of intracellular cysteine. Using targeted metabolite analysis, we observe that cysteine is initially rapidly interconverted to non-reactive cystine in vivo. A time course revealed that cells systematically convert excess cysteine to inert thiol forms; initially to cystine, and subsequently to cystathionine, S-Adenosyl-L-homocysteine (SAH) and S-Adenosyl L-methionine (SAM), in addition to eventually accumulating glutathione (GSH) and polyamines. Microarray based gene expression studies revealed the upregulation of arginine/ornithine biosynthesis a few hours after the cysteine overload, and suggest that the non-toxic, non-reactive thiol based metabolic products are eventually utilized for amino acid and polyamine biogenesis, thereby enabling cell growth. Thus, cells can handle potentially toxic amounts of cysteine by a combination of thiol trapping, metabolic redistribution to non-reactive thiols and subsequent consumption for anabolism.

Laparoscopic splenectomy using conventional instruments

Introduction:

Laparoscopic splenectomy (LS) is an accepted procedure for elective splenectomy. Advancement in technology has extended the possibility of LS in massive splenomegaly [Choy et al., J Laparoendosc Adv Surg Tech A 14(4), 197–200 (2004)], trauma [Ren et al., Surg Endosc 15(3), 324 (2001); Mostafa et al., Surg Laparosc Endosc Percutan Tech 12(4), 283–286 (2002)], and cirrhosis with portal hypertension [Hashizume et al., Hepatogastroenterology 49(45), 847–852 (2002)]. In a developing country, these advanced gadgets may not be always available. We performed LS using conventional and reusable instruments in a public teaching the hospital without the use of the advanced technology. The technique of LS and the outcome in these patients is reported.

Materials and Methods:

Patients undergoing LS for various hematological disorders from 1998 to 2004 were included. Electrocoagulation, clips, and intracorporeal knotting were the techniques used for tackling short-gastric vessels and splenic pedicle. Specimen was delivered through a Pfannensteil incision.

Results:

A total of 26 patients underwent LS. Twenty-two (85%) of patients had spleen size more than 500 g (average weight being 942.55 g). Mean operative time was 214 min (45–390 min). The conversion rate was 11.5% (n = 3). Average duration of stay was 5.65 days (3–30 days). Accessory spleen was detected and successfully removed in two patients. One patient developed subphrenic abscess. There was no mortality. There was no recurrence of hematological disease.

Conclusion:

Laparoscopic splenectomy using conventional equipment and instruments is safe and effective. Advanced technology has a definite advantage but is not a deterrent to the practice of LS.

Iatrogenic gastric fistula due to inappropriate placement of intercostal drainage tube in a case of traumatic diaphragmatic hernia

A 26-year-old, 30 weeks primigravida presented with a gastric fistula through a left intercostal drain, which was inserted for drainage of suspected haemopneumothorax following minor trauma. It was confirmed to be a diaphragmatic hernia, with stomach and omentum as its contents. On exploratory laparotomy, disconnection of the tube and fistulous tract, with reduction of herniated contents and primary suturing of stomach was carried out. Diaphragmatic reconstruction with polypropylene mesh was also carried out. Post-operative recovery was uneventful with full lung expansion by 3rd postoperative day. Patient was asymptomatic at follow-up 6 months.

Laparoscopic repair of Morgagni hernia in adult

Foramen of Morgagni hernias require surgical treatment; laparoscopic repair is another option with lower morbidity. We describe a 35-year-old man with Morgagni hernia treated successfully by laparoscopy.

Laparoscopic cholecystectomy in patient with portal cavernoma and portal hypertension

Successful laparoscopic cholecystectomy has been reported in patients with cirrhosis of liver with portal hypertension; the procedure has, however, not been reported in patients with portal vein thrombosis, portal cavernoma and portal hypertension. We report an 18-year-old man with portal hypertension due to portal vein thrombosis and portal cavernoma who had symptomatic gallstone disease and was successfully treated with laparoscopic cholecystectomy.

Ruptured true aneurysm of the splenic artery: an unusual cause of haemoperitoneum

True aneurysm of the splenic artery is rare. Two cases of ruptured true splenic artery aneurysms are presented. The first patient was a 62-year-old female who presented within 6 hours of the onset of symptoms. The other was a 27-year-old non-alcoholic male patient who was admitted in a state of shock after 2 days of observation in a peripheral hospital. Both patients had haemoperitoneum and were subjected to exploratory laparotomy. Aneurysmectomy was performed in both the patients in addition to left splenopancreatectomy in the first case and splenectomy in the second. However, due to the prolonged preoperative shock, the second patient succumbed on the third postoperative day.

Laparoscopic management of hydatid cyst of liver

We describe the laparoscopic excision of a hydatid cyst in the liver. During the procedure, done after treatment with the scolicidal agents praziquantel and albendazole, care was taken to prevent spillage of scolices during evacuation of contents and to excise the entire germinal epithelium. The patient had no immediate or short-term complications and is asymptomatic 3 months later.

Synchronous primary adenocarcinoma of small and large bowel

Synchronous cancer of the small and large bowel is rare. We report a 45-year-old woman with synchronous primary cancer of the jejunum and descending colon who presented with intestinal obstruction.

Bioerodible polymers for ocular drug delivery

Development of ophthalmic drug-delivery systems has always been challenging. The commonly used route for drug delivery to the anterior segment of the eye has been the conjunctival cul-de-sac. Because of drawbacks associated with this route, new approaches have been investigated for delivery of drugs to the eye by means of polymeric delivery systems. Development of controlled drug-release devices has been a major step forward in this respect. Bioerodible polymers have been at the forefront of such systems. They are very important because they eliminate the need for removing the implant after complete drug release. Bioerodible polymers have been divided into three classes based on their mechanism of hydrolysis: Type I--hydrolysis of crosslinked hydrogels; Type II--solubilization by ionization or hydrolysis of linear polymers; and Type III--biodegradation by backbone cleavage. Polymers from all three classes are discussed in detail in this review.

Fetus in fetu or a retroperitoneal teratoma--a controversy revisited. A case report and review of literature

A 25 year old man male presented with a lump in the left side of the abdomen. Ultrasonography revealed an echogenic retroperitoneal mass with hyperechoic areas within it suggestive of bone. CT scan confirmed the presence of a large retroperitoneal mass with bone within it. On exploration there was a large encapsulated retroperitoneal lump. There was a soft tissue mass within the lump surrounded by a yellow pultaceous material admixed with pus. Examination of the specimen showed a bone at the cephalic end with teeth embedded within it. There were two limb buds near the cephalic end. The whole specimen was covered with skin with all its appendages. There was coelomic cavity present. The distinction between fetus in fetus and teratoma has for long been the subject of controversy. According to the criteria described by Willis, there should be a vertebral axis present to make the diagnosis of fetus in fetu. But there have been a few reports where cases have been described as fetus in fetu even in the absence of a vertebral axis. A review of the literature concerning this controversy is briefly given.

Reverse micellar extraction of antibiotics from aqueous solutions

Several antibiotics such as erythromycin, oxytetracyclin, benzylpenicillin, and actidione were extracted from aqueous buffers into reverse micellar solution of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) in isooctane and recovered with high efficiency under mild conditions. Preliminary experiments with oxytetracycline dissolved in a fermentation broth indicate that the antibiotic can be selectively extracted from the broth and recovered efficiently without serious loss of potency.

Development of a novel controlled-release system for gastric retention

PURPOSE

We report on the development of a novel controlled-release gastric retention system, which consists of a matrix tablet, coated with a permeable membrane. When immersed in simulated gastric fluid, the tablet expands. The tablet remains expanded for eighteen to twenty hours, during which time the drug is released. The tablet then either disintegrates into fragments or loses its integrity.

METHODS

Tablets containing a soluble drug (chlorpheniramine maleate, i.e., CPM) and a poorly soluble drug (riboflavin 5' phosphate, i.e., R5'P) were compressed. They were coated with a permeable and elastic polymer (Eudragit). Dissolution profiles of these tablets were studied. The changes in the pH, viscosity, and deformation characteristics as a function of time were measured.

RESULTS

Carbopol provided a firm structure to the swollen tablet. Polyvinyl pyrrolidone XL (PVP XL) contributed to the swelling of the tablet. Carbonates provided the initial alkaline micro-environment for Carbopol to gel and conferred buoyancy to the tablet. Coating provided the support needed for the core to remain intact during drug release and, at the same time, it allowed drug release due to its permeable nature. During release, the gelling properties of Carbopol lessened, resulting in a decrease in the firmness of the core. This was evident from the decrease in the viscosity of the core. The energy required at 50% strain also decreased as the drug release progressed.

CONCLUSIONS

When this tablet is ingested, the chances of its elimination through the pylorus should be greatly reduced due to tablet's expansion, and due to its disintegration or loss in integrity it should then be expelled out of the stomach at the end of the drug release.

Risk factors for acute care transfer among traumatic brain injury patients

OBJECTIVE

Acute inpatient traumatic brain injury (TBI) rehabilitation has seen a jump in complexity of medical patient care over the past several years, often necessitating transfer back to an acute care facility. The purpose of this study was to determine the association between selected clinical variables and transfer from inpatient rehabilitation to an acute care facility.

DESIGN

A retrospective review of cases from 1992 to 1994.

SETTING

A TBI unit in a freestanding rehabilitation hospital.

PATIENTS

Twenty-two patients were identified as having received acute care transfer. This group was compared with 78 patients, admitted in the same interval, who did not require acute care transfer. The variables evaluated included recent surgery, pneumonia, fracture, intracranial blood, tracheostomy use, percutaneous feeding tube use, deep venous thrombosis, focal neurological examination, following simple commands, serum sodium level of < 135 mmol/L, serum white blood cell count of > 11,000 cells/microL, and serum hemoglobin level of < 10.0 g/dl.

ANALYSIS

Chi-square analysis was performed on the association between acute care transfer and the noted variables.

RESULTS

History of pneumonia (p < .03) and history of recent surgery (p < .02) were both associated with acute care transfer, and serum hemoglobin of < 10.0 g/dL had a trend towards association (p < .10).

CONCLUSION

Physiatrists caring for the TBI patient may warrant more acute observation of individuals with these parameters to prevent the problems necessitating acute care transfer.

Factors predicting morbidity and mortality in intestinal fistulae

INTRODUCTION

Intestinal fistulae are a daunting clinical problem.

AIM

To evaluate the influence of various severity factors on morbidity and mortality in patients with intestinal fistulae.

METHOD

In 29 patients with intestinal fistulae, eight severity factors, viz., age, associated bowel disease, anemia, hypoalbuminemia, high-output fistula, category IV fistula, excoriation of skin surrounding the stoma, and sepsis, were analyzed prospectively to assess their effect on healing of fistulae and mortality. Chi-squared test with Yates' correction was used.

RESULTS

Age, presence of associated bowel disease, and hemoglobin levels had no significant effect on healing or mortality. Hypoalbuminemia, category IV fistulae, presence of local skin excoriation, and sepsis significantly delayed healing (p < 0.05). High-output fistula, category IV fistula, local skin excoriation, and sepsis were significantly associated with high mortality (p < 0.05).

CONCLUSION

Identification of these prognostic factors in intestinal fistulae may guide the need for more intensive care or intervention.

Chicken gonadotropin-releasing hormone II increases plasma catecholamines in the bullfrog

The aim of the present experiments was to test the effects of two native neuropeptides, [His5,Trp7,Tyr8]gonadotropin-releasing hormone (chicken GnRH II) and [Trp7,Leu8]GnRH (salmon GnRH), on the sympathoadrenal system of chronically cannulated, conscious bullfrogs (Rana catesbeiana). We observed that i.v. injection of chicken GnRH II or salmon GnRH increased plasma noradrenaline and adrenaline concentrations, at doses that did not significantly affect arterial blood pressure or heart rate. Chicken GnRH II was 10 times more potent than salmon GnRH for increasing plasma adrenaline, while the two neuropeptides were equally effective in raising noradrenaline concentration. These observations are consistent with a regulatory role for chicken GnRH II in the bullfrog sympathoadrenal system.