Optical sensing of mechanical pressure based on diffusion measurement in polyacrylamide cell-like barometers.

Diffusion and transport of small molecules within hydrogel networks are of high interest for biomedical and pharmaceutical research. Herein, using fluorescence correlation spectroscopy (FCS), we experimentally showed that the diffusion time in the hydrogel was directly related to the mechanical state (compression or swelling) and thus to the volume fraction of the gel. Following this observation, we developed cell-like barometers in the form of PAA microbeads, which when incorporated between cells and combined with a diffusion-based optical readout could serve as the first biosensors to measure the local pressure inside the growing biological tissues. To illustrate the potential of the present method, we used multicellular spheroids (MCS) as a tissue model, and it was observed that the growth-associated tissue stress was lower than 1 kPa, but significantly increased when an external compressive stress was applied.

Could the complications of megacolon be avoided by monitoring the risk patients? cases report.

We report 2 cases of megacolon associated with cerebrovascular accident and neuropsychiatric drug consumption. Case report 1: a 75-year-old woman with diabetes mellitus, hypertension, tachycardia with atrial fibrillation, bilateral pleural effusions and previous cerebral hemorrhage was admitted in our hospital. She presented clouded sensorium and abdominal distension, with closed alvus. The CT scan showed a distension of the colon, with severe fecal impaction. A volvulus of the sigma was found at surgical intervention.Case report 2: a 59-year-old man with a medical history of oligophrenia was admitted to our hospital for acute abdomen.He presented stupor and closed alvus with abdominal distension. The abdominal CT scan showed a dolichosigma, with fecal impaction. The patient was submitted to a laparotomy and a two millimetres perforation of the sigma was found.The sigma had a diameter of 28 cm and a length of 75 cm.Even if a clear correlation has not been found yet, anomalies of the regulation of the gastro-intestinal motility can occur at different levels in patients with psychiatric or cerebrovascular diseases and drug consumption with anticholinergic properties,and they should be carefully monitored. The purpose is an early diagnosis of colon function anomalies in order to avoid potentially fatal complications.

[Retrospective study on the effects of a whey protein concentrate on body composition in 262 sarcopenic tube fed patients]. / Studio retrospettivo sugli effetti di un concentrato di proteine del siero del latte sulla composizione corporea di 262 pazienti in nutrizione enterale affetti da sarcopenia.

AIM: As pointed in ESPEN guidelines on the use of bioelectrical impedance analysis (BIA), "body cell mass (BCM) is the protein rich compartment which is affected in catabolic states, and loss of BCM is associated with poor clinical outcome". Whey proteins are known to improve lean mass in many conditions. We retrospectively evaluated the effects of a WP concentrate with high cysteine content (WPHCC) on BCM of 262 sarcopenic tube fed patients (pts). METHODS: Two hundred sixty-two sarcopenic tube fed pts (130 males, mean age 68,1±15,6 years) were given daily supplemental WPHCC (0.7±0.2 g/kg body weight) after their usual feeding formula, with the aim to improve their BCM. Each patient received a multifrequency impedance test before and after the beginning of WPHCC supplementation (mean follow-up: 4.2±2.8 months). Fifty percent of patients were affected by neurodegenerative diseases, 36% by cancer, 14% by other conditions. RESULTS: BCM, body weight and fat mass significantly improved (P<0.01) after treatment. No severe side effects were recorded. A slight increase in blood urea was observed. CONCLUSION: In our population WPHCC have been safe and effective in improving BCM. WPHCC could be useful to improve BCM in sarcopenic tube fed pts, although renal function should be monitored.

Primary anastomosis vs Hartmann procedure in acute complicated diverticulitis. Evolution over the last twenty years.

BACKGROUND/AIMS: Aim of this review is to assess the role and indications for primary sigmoidectomy with direct anastomosis for diverticulitis comparing it with the Hartmann's procedures. METHODS: A literature search was performed using MEDLINE (PubMed), Google Scholar and The Cochrane Library and the articles from January 1990 until June 2011 were analyzed. All patients were divided into three groups: primary anastomosis (PA), primary anastomosis and stoma protection (SP) and Hartmann's procedure (HP). Number of patients, overall mortality and morbidity, the rate of fistulization, the rate of reversal after SP (RSP) and after HP (RHP) and the Hinchey classification have been considered. RESULTS: The mortality was of 38/1010 patients (3.8%) for PA, 11/153 patients (7.2%) for SP and 139/800 patients (17.4%) for HP. The morbidity was reported in 103/325 patients (31.7%) in PA, in 23/97 patients (23.7%) in SP and in 290/586 patients (49.5%) in HP. Fistula formation was recorded in 35/625 patients (5.6%) for PA, in 10/149 patients (16.4%) for RSP and 11/426 patients (6.4%) for RHP. The intestinal continuity was restored in 82/628 patients (56.9%) who underwent SP and in 315/581 patients (54.2%) undergoing HP. A total of 790 patients (54.5%) were classified in class I-II Hinchey and total of 659 patients (45.5%) was classified in class III-IV Hinchey. CONCLUSION: The PA has a lower morbidity and mortality in relation to the HP and except some limited indications, should be used as treatment of choice in the case of diverticulitis.

Endoscopic therapy for type B surgical biliary injury in a patient with short cystic duct.

Anatomical variations of the cystic duct are well-defined. The presence of short or absent cystic duct is unusual and represents a co-factor of biliary injury especially during laparoscopic cholecystectomy. Thus, its knowledge is important to avoid ductal injury in hepato-biliary surgery. We experienced the case of a 40-year-old woman with symptomatic cholelitiasis, who underwent to laparoscopic cholecystectomy. At surgery, an accidental bile duct lesion was carried, during Calot's triangle dissection, due the particular difficulties in dissecting an extremely short cystic duct found at the junction of the common hepatic duct and common bile duct. No vascular anomalies were present. The biliary leakage from the common bile duct was intraoperative identified and subsequentially treated by the endoscopic method. Laparoscopic cholecystectomy with sequential biliary endoprosthesis insertion was completed without conversion to open surgery. The endoscopic stenting was the definitive treatment for the leakage. No evidence of biliary stent complication was observed during the follow-up. This report documents a case of short cystic duct with particular emphasis to the biliary injury risk during the laparoscopic dissection of "unusual" Calot's triangle, and examines our mini-invasive therapeutic strategies in the management of bile leakage after laparoscopic cholecystectomy.

Effect of the 5-HT3 receptor antagonist, ondansetron, on gastric size in dyspeptic patients with impaired gastric accommodation.

BACKGROUND: A reduction of gastric accommodation after a meal has been documented in patients with idiopathic dyspepsia. In these patients the administration of a 5-HT3 receptor antagonist may reduce some of the dyspeptic symptoms; it is not clear however, whether these drugs influence gastric adaptation to distension as well. AIM: To evaluate the effects of the 5-HT3 receptor antagonist, ondansetron, on gastric distension after a liquid meal in dyspeptic patients with reduced gastric accommodation. METHODS: Before and after a 500 ml water load, gastric accommodation (area of the proximal and distal stomach) was evaluated using real-time ultrasonography in 21 idiopathic dyspepsia patients and 26 healthy controls. In dyspeptic patients, the test was repeated twice: after the administration of placebo and after ondansetron 8 mg i.v. (in both cases, 15 min prior to the water load). Secondary outcomes were epigastric pain, fullness and nausea as assessed by a visual analogue scale at basal and after ondansetron. RESULTS: Fasting gastric size was similar in dyspeptic and controls. Compared with controls, dyspeptic patients showed a statistically significant smaller area of the proximal stomach (14.7+/-1.2 cm(2) vs. 18.6+/-1.4 cm(2), respectively; p=0.0247). In dyspeptic patients, gastric proximal and distal size did not change significantly following placebo, whereas after the administration of ondansetron the mean area of the proximal and distal stomach significantly increased (proximal stomach: 14.6+/-1.6 cm(2) placebo, 20.4+/-1.9 cm(2) ondansetron, p=0.0095; distal stomach: 8.9+/-0.9 placebo, 11.4+/-1.2cm(2) ondansetron, p=0.0409). Of the symptoms, only nausea was significantly reduced after ondansetron. CONCLUSION: In dyspeptic patients with impaired gastric accommodation, ondansetron reverts gastric accommodation to within the range of controls.

[Membrane platelet fatty acids: biochemical characterisation of the ischemic cardiovascular disease, characteristics of the paediatric age, through an artificial neural network interpretation]. / Acidi grassi di membrana delle piastrine: tipizzazione biochimica della cardiopatia vascolare ischemica e caratteristiche dell'età pediatrica nell'interpretazione di una Rete Neurale Artificiale.

During the last 30 years, a huge research has been performed about the markers involved in the atherogenetic process and in the fatty acid thrombogenetic effect. More recently many studies have been made on the biochemical aspects of the saturated fatty acids with respect to the cardiovascular risk, in particular, the Stearic Acid (SA). Because of the peculiar characteristic of the platelets in the control of the thrombogenetic risk, we have investigated the platelet fatty acid profile in three groups of subjects: supposed healthy (n = 60), ischemic (n = 50), young children (n = 118). The aim of the study was to understand wich of the fatty acids could be evaluated as markers of the ischemic cardiovascular pathology and to have the possibility to classifie the subjects using the artificial neural network (ANN) system. The results highlight the peculiar position of the Oleic Acid, Linoleic Acid and Arachidonic Acid. According to the ANN results of the ischemic subjects, the young children were in the same position. Because this result is not commonly accepted, as children are healty, we have looked for a reason. There are well strong reasons to believe that all this is due to the stearic acid wich is extremely higher than the stearic acid of all the other subjects investigated. Particularly it has been underlined the possibility to modify the platelet stearic and oleic acid to obtain a better saturation index (Stearic/Oleic ratio). This could bring to a better control of the cardiovascular risk. It is possible, according with the results obtained, to open a new field of research on the lipid metabolism of the young children in relation to the atherogenesis. It is the first time that an observation on the platelet membrane phospholipid stearic acid is made in comparison to other adult subjects and a plausible explanation is given about the protection of the young children against the cardiovascular disease.

Peppermint oil (Mintoil) in the treatment of irritable bowel syndrome: a prospective double blind placebo-controlled randomized trial.

INTRODUCTION: The use of peppermint oil in treating the irritable bowel syndrome has been studied with variable results probably due to the presence of patients affected by small intestinal bacterial overgrowth, lactose intolerance or celiac disease that may have symptoms similar to irritable bowel syndrome. AIM: The aim of the study was to test the effectiveness of enteric-coated peppermint oil in patients with irritable bowel syndrome in whom small intestinal bacterial overgrowth, lactose intolerance and celiac disease were excluded. METHODS: Fifty-seven patients with irritable bowel syndrome according to the Rome II criteria, with normal lactose and lactulose breath tests and negative antibody screening for celiac disease, were treated with peppermint oil (two enteric-coated capsules twice per day or placebo) for 4 weeks in a double blind study. The symptoms were assessed before therapy (T(0)), after the first 4 weeks of therapy (T(4)) and 4 weeks after the end of therapy (T(8)). The symptoms evaluated were: abdominal bloating, abdominal pain or discomfort, diarrhoea, constipation, feeling of incomplete evacuation, pain at defecation, passage of gas or mucus and urgency at defecation. For each symptom intensity and frequency from 0 to 4 were scored. The total irritable bowel syndrome symptoms score was also calculated as the mean value of the sum of the average of the intensity and frequency scores of each symptom. RESULTS: At T(4), 75% of the patients in the peppermint oil group showed a >50% reduction of basal (T(0)) total irritable bowel syndrome symptoms score compared with 38% in the placebo group (P<0.009). With peppermint oil at T(4) and at T(8) compared with T(0) a statistically significant reduction of the total irritable bowel syndrome symptoms score was found (T(0): 2.19+/-0.13, T(4): 1.07+/-0.10*, T(8): 1.60+/-0.10*, *P<0.01 compared with T(0), mean+/-S.E.M.), while no change was found with the placebo. CONCLUSION: A 4 weeks treatment with peppermint oil improves abdominal symptoms in patients with irritable bowel syndrome.

Cell-like pressure sensors reveal increase of mechanical stress towards the core of multicellular spheroids under compression.

The surrounding microenvironment limits tumour expansion, imposing a compressive stress on the tumour, but little is known how pressure propagates inside the tumour. Here we present non-destructive cell-like microsensors to locally quantify mechanical stress distribution in three-dimensional tissue. Our sensors are polyacrylamide microbeads of well-defined elasticity, size and surface coating to enable internalization within the cellular environment. By isotropically compressing multicellular spheroids (MCS), which are spherical aggregates of cells mimicking a tumour, we show that the pressure is transmitted in a non-trivial manner inside the MCS, with a pressure rise towards the core. This observed pressure profile is explained by the anisotropic arrangement of cells and our results suggest that such anisotropy alone is sufficient to explain the pressure rise inside MCS composed of a single cell type. Furthermore, such pressure distribution suggests a direct link between increased mechanical stress and previously observed lack of proliferation within the spheroids core.

Effect of an acute intraluminal administration of capsaicin on oesophageal motor pattern in GORD patients with ineffective oesophageal motility.

Ineffective oesophageal motility (IOM) is a functional disorder affecting about 50% of gastro-oesophageal reflux disease (GORD) patients. This disease in a severe form limits the clearing ability of the oesophagus and is considered one of the predictive factors for poorer GORD resolution. Capsaicin, the active compound of red pepper, exerts a prokinetic effect on oesophageal motility in healthy subjects by increasing the amplitude of body waves, even if no evidence exists on its possible role in situations of reduced motility. The aim of the study was to evaluate the effect of an acute administration of capsaicin on the oesophageal motor pattern in a group of GORD patients affected by severe IOM. Twelve GORD patients with severe IOM received an intra-oesophageal administration of 2 mL of a red pepper-olive oil mixture and 2 mL of olive oil alone serving as a control during a stationary manometry. The motor patterns of the oesophageal body and lower oesophageal sphincter (LOS) were analysed at baseline and after the infusion of the two stimuli. The administration of capsaicin induced a significant improvement in oesophageal body contractility when compared with baseline. The velocity of propagation of waves and the LOS basal tone remained unchanged. The motor pattern was unaltered by the administration of olive oil alone. An acute administration of capsaicin seems to improve the motor performance of the oesophageal body in patients with ineffective motility. Whether this could represent the basis for further therapeutic approaches of GORD patients needs further study.

Rifaximin in patients with lactose intolerance.

BACKGROUND: Abdominal symptoms linked to lactose malabsorption may be caused by metabolic activity of colonic bacteria. Rifaximin, a non-absorbable rifampycin derivative, is active against colonic bacteria, it may be useful in the treatment of lactose intolerance. AIM: The aim of this study has been to evaluate short-term rifaximin therapy in patients with lactose intolerance. METHODS: Thirty-two patients with lactose intolerance diagnosed using the hydrogen lactose breath test were studied. Fourteen patients received rifaximin 800 mg/day for 10 days, 13 patients followed a diet without milk for 40 days and 5 patients received a placebo for 10 days. Total breath H(2) excretion expressed as area under the curve, and the symptom score were evaluated in all patients at the start, and subsequently after 10 and 40 days. RESULTS: In the 14 patients who received rifaximin for 10 days, area under the curve at day 10 and day 40 was statistically significantly lower than the one computed at basal (P<0.01). Diet reduced area under the curve progressively reaching statistical significance at day 40, while the placebo did not change area under the curve throughout the study. The total symptom score significantly improved after rifaximin and diet. CONCLUSION: In patients with lactose intolerance, a 10-day therapy with rifaximin as well as 40-day diet without lactose reduces the area under the curve and the symptom score.

Clinical efficacy and electropharmacology of continuous intravenous amiodarone infusion and chronic oral amiodarone in refractory ventricular tachycardia.

The clinical efficacy and electropharmacologic effects of continuous intravenous (i.v.) amiodarone infusion (10 to 20 mg/kg/day for 4 to 7 days) followed by chronic oral amiodarone therapy (400 to 800 mg/day for 24 to 53 days) were evaluated in 17 patients with refractory sustained ventricular tachycardia (VT) or ventricular fibrillation. Intravenous amiodarone infusion prolonged the RR interval (from 754 +/- 85 to 860 +/- 157 ms, p less than 0.05), PR interval (from 192 +/- 53 to 212 +/- 54 ms, p less than 0.01) QRS duration (from 103 +/- 21 to 117 +/- 25 ms, p less than 0.001) and QTc interval (from 423 +/- 22 to 466 +/- 31 ms, p less than 0.001). Chronic oral amiodarone treatment had similar but more pronounced effects on electrocardiographic intervals. The ventricular effective refractory period tended to prolong after i.v. amiodarone infusion (p less than 0.1 to greater than 0.05) but prolonged significantly after chronic oral amiodarone (p = 0.025). Mean serum amiodarone concentration was 1.7 +/- 1.0 mg/liter with infusion and 1.5 +/- 0.6 mg/liter with oral therapy. Intravenous amiodarone infusion suppressed spontaneous VT in 5 of 9 patients with frequent VT recurrences, but had no effect on cycle length of spontaneous VT. Chronic amiodarone therapy either suppressed spontaneous VT recurrences or prolonged cycle length during VT recurrences. VT induction after i.v. amiodarone was not predictive of VT induction or spontaneous VT recurrences after chronic oral amiodarone treatment. Thus, i.v. amiodarone has limited value in acute control of VT and clinical or electrophysiologic response to it is not predictive of long term therapeutic results with amiodarone.

Role of antimicrobial susceptibility testing on efficacy of triple therapy in Helicobacter pylori eradication.

BACKGROUND: Helicobacter pylori treatment failure may be due to resistance to macrolides and 5-nitroimidazoles. AIM: To test whether a preliminary in vitro susceptibility test of H. pylori to tinidazole and clarithromycin and a consequent specific regimen could improve the eradication rate. METHODS: A total of 109 consecutive H. pylori-positive patients with dyspeptic symptoms were included. At endoscopy, biopsy from the antrum was obtained for H. pylori culture and antimicrobial susceptibility testing. Fifty-six patients were treated with omeprazole, tinidazole and clarithromycin for 10 days (group OTC) and 53 patients received therapy on the basis of the susceptibility test (group SUSC). Treatment success was evaluated by the 13C-urea breath test 1 month after the end of therapy. RESULTS: Eight patients dropped out. Overall primary resistance to clarithromycin, tinidazole and both antibiotics was 13%, 33% and 4%, respectively. In group OTC, H. pylori was eradicated in 81% and 75% of patients by per protocol and intention-to-treat analysis, respectively. Per protocol and intention-to-treat eradication rates for group SUSC were 98% and 91% (P < 0.05 vs. group OTC). CONCLUSIONS: These data show that in H. pylori infection, antibiotic therapy based on the results of culture and susceptibility testing gives, in comparison to standard therapy, a significant improvement in eradication rate.

A computerised program for TPN.

A computerised program devised to manage patients undergoing TPN has been operating in the Parenteral and Enteral Nutrition Unit of the II Clinica Chirurgica of the University of Rome. The program includes sections to manage information, monitoring and therapy. The package was compiled using the new Language C, which is well adapted to our model. In a pilot study the program was successfully applied to the management of 15 patients. Computers and information technology have developed to the point where they are well suited to this type of biological application. Language C, which in this study, was used for the first time in this field, offers practically unlimited possibilities for development.

Surgery of gastric cancer: treatment of post-operative enterocutaneous fistulas.

Anastomosis dehiscences after gastrectomy are a major post-operative complication often resulting in the death of the patient. 13 patients with dehiscences resulting in enterocutaneous fistulae have been treated with parenteral and/or enteral nutrition. Spontaneous closure rate was 84.6% and mean time for fistula closure was 22.4 days from the onset of nutritional treatment. On the base of nutritional effectiveness no difference could be found between enteral and parenteral nutrition in this series.

Evaluation of dyspeptic symptoms in patients with and without Helicobacter pylori infection and normal upper gastrointestinal endoscopy.

BACKGROUND: A relationship between Helicobacter pylori infection and dyspeptic symptoms has not yet been demonstrated. AIM: To evaluate any possible difference in symptom score between dyspeptic patients with and without H. pylori infection who have normal upper gastrointestinal endoscopy and no other appreciable gastrointestinal or systemic disease. PATIENTS: A series of consecutive patients affected by upper abdominal disturbances completed a symptoms questionnaire before undergoing upper gastrointestinal endoscopy with a rapid urease test to detect H. pylori infection. Patients with normal upper gastrointestinal endoscopy and abdominal ultrasound were included in the study. The symptoms assessed were burping and belching, bloating, odynophagia, dysphagia, postprandial fullness, heartburn, early satiety, nausea, vomiting, regurgitation, sour taste in mouth, epigastric pain at fasting, epigastric pain postprandial, epigastric pain nocturnal, and pain in right hypocondrium and were scored in terms of intensity and frequency on a scale from 0 to 4. RESULTS: The total number of patients who met the inclusion criteria was 263 out of 1187 examined. A total of 113 H. pylori-positive and 150 H. pylori-negative patients were compared. Among the symptoms evaluated, belching and bloating and heartburn were present in more than 50% of patients of both groups. No statistical difference was found in terms of presence or absence of each symptom, and intensity or frequency between H. pylori-positive and -negative patients. CONCLUSION: H. pylori infection does not seem to be associated with a specific symptom in patients with upper abdominal complaints and normal upper gastrointestinal endoscopy.

Chronic effects of amiodarone in patients with refractory ventricular tachycardia.

We examined the chronic electrophysiologic, systemic, and pharmacologic effects of chronic oral amiodarone therapy in 24 patients with refractory ventricular tachycardia and organic heart disease. Chronic amiodarone therapy resulted in significant increases in R-R interval (from 798 +/- 182 msec to 912 +/- 100 msec; P less than 0.01), P-R interval (from 205 +/- 66 msec to 221 +/- 87 msec; P less than 0.02), QRS duration (from 103 +/- 24 msec to 115 +/- 28 msec; P less than 0.001), and Q-Tc interval (from 413 +/- 48 msec to 470 +/- 46 msec; P less than 0.001). Significant increases were also noted in P-A interval (from 36 +/- 14 msec to 45 +/- 13 msec; P less than 0.05), A-H interval (from 119 +/- 61 msec to 141 +/- 87 msec; P less than 0.02), and H-V interval (from 52 +/- 12 msec to 64 +/- 11 msec; P less than 0.001). Electrophysiologic parameters showing changes included corrected sinus node recovery time (from 271 +/- 140 msec to 425 +/- 122 msec; P less than 0.01), the effective refractory period of the atrium (from 263 +/- 32 msec to 321 +/- 47 msec; P less than 0.01), the effective refractory period of the atrioventricular node (from 348 +/- 109 msec to 478 +/- 157 msec; P less than 0.001), the effective refractory period of the ventricle (from 253 +/- 21 msec to 291 +/- 28 msec; P less than 0.001), the atrial pacing cycle length producing A-V nodal Wenckebach (from 436 +/- 109 msec to 531 +/- 95 msec; P less than 0.001), and the functional refractory period of the A-V node (from 422 +/- 68 msec to 499 +/- 95 msec; P less than 0.001). Programmed electrical stimulation performed after 21-88 (mean 31) days of treatment was highly predictive of long-term results if suppression of arrhythmia induction was demonstrated (12 patients) or if the spontaneous arrhythmia was reinduced (5 patients). Induction of morphologically new ventricular tachyarrhythmias was frequent (42%) but had a low spontaneous recurrence rate (10%) during follow-up. Systemic parameters on chronic amiodarone therapy showed significant increases in total T4 and reverse T3, with no change in pulmonary function tests or left ventricular ejection fraction. Serum amiodarone levels at chronic electrophysiologic study ranged from 0.44-4.10 (mean 1.3) micrograms/ml. Long-term follow-up (2.5 to 20 months) demonstrated a marked improvement in clinical symptoms and mortality, but a significant recurrence rate of a well-tolerated slower arrhythmia persisted. Adverse effects on chronic amiodarone therapy were frequent (10 patients) and often disabling but required drug discontinuation in only 1 patient.

Management of lymphatic fistulas by total parenteral nutrition.

Lymphatic fistula is a rare surgical complication, which mainly occurs after cervical or retroperitoneal lymph node dissection and which frequently requires a surgical repair. A small series of nine postoperative lymphatic fistulas treated conservatively with total parenteral nutrition (TPN) is reported. All the patients were malnourished at the beginning of the TPN, and all exhibited an objective improvement of their nutritional status after completion of the treatment. Due to the interruption of the enteral alimentation or to the nutritional repletion, spontaneous closure of the fistula was achieved in eight of nine patients treated with TPN longer than 1 week. The authors conclude that whenever the immediate surgical repair is not recommended, or it is not successful, a 2- to 3-week course of TPN may be used with the chance of spontaneous healing. In any case, patients conservatively treated by TPN can undergo a delayed operation with minimal risk because of the improved nutritional status.

Qualitative organic analysis. Part 2. Identification of drugs by principal components analysis of standardized TLC data in four eluent systems and of retention indices on SE 30.

The principal components (PC) analysis of standardized Rf values in four eluent systems [ethyl acetate/methanol/30% ammonia (85:10:15), cyclohexane/toluene/diethylamine (65:25:10), ethyl acetate/chloroform (50:50), and acetone with the plate dipped in potassium hydroxide solution] and of gas chromatographic retention indices in SE 30 for 277 compounds provided a two-principal-components model that explains 82% of the total variance. The scores plot allowed identification of unknowns or restriction of the range of inquiry to very few candidates. Comparison of these candidates with those selected from another PC model derived from TLC data only allowed identification of the drug in all the examined cases.