Multimodality imaging of extra-nodal lymphoma in the head and neck.

Malignant lymphomas represent approximately 5% of all malignant neoplasms of the head and neck. The head and neck region is the second most frequent anatomical site of extra-nodal lymphomas (after the gastrointestinal tract). Most are non-Hodgkin's lymphomas of B-cell lineage, and overall diffuse large B-cell lymphoma is the most common type. They can present in highly variable appearances in different anatomical subsites in the head and neck. There is little literature on their imaging appearances on different imaging methods including ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and integrated positron-emission tomography (PET)/CT. The review aims to illustrate the presentation of histopathological-proven extra-nodal lymphoma in the head and neck using various imaging methods.

Patterns of COVID-19 on computed tomography imaging.

PURPOSE: As the designated tertiary referral centre for infectious diseases in Hong Kong, our hospital received the city's first group of patients diagnosed with coronavirus disease 2019 (COVID-19). Herein, we studied the earliest patients admitted to our centre in order to clarify the typical radiological findings, particularly computed tomography (CT) findings, associated with COVID-19. METHODS: From 22 January 2020 to 29 February 2020, 19 patients with confirmed COVID-19 underwent high-resolution or conventional CT scans of the thorax in our centre. The CT imaging findings of these patients with confirmed COVID-19 in Hong Kong were reviewed in this study. RESULTS: Ground-glass opacities (GGO) with peripheral subpleural distribution were found in all patients (100%). No specific zonal predominance was observed. All lobes were involved in 16 (84.2%) patients, focal subsegmental consolidations were observed in 14 (73.7%) patients, and interlobular septal thickening was present in 12 (63.2%) patients. No mediastinal lymph node enlargement, centrilobular nodule, or pleural effusion was detected in any of the patients. Other imaging features present in several patients include bronchial dilatation, bronchial wall thickening, and crazy-paving patterns. CONCLUSIONS: Peripheral subpleural GGO without zonal predominance in the absence of centrilobular nodule, pleural effusion, and lymph node enlargement were consistent findings in patients with confirmed COVID-19. The observed radiological patterns on CT scans can help identify COVID-19 and assess affected patients in the context of the ongoing outbreak.

Rat fibroblast cells overexpressing kinase-inactive human insulin receptors are insulin responsive: influence of growth conditions.

The effects of insulin to stimulate metabolic and mitogenic responses were examined in Rat 1 fibroblast cells that overexpressed either normal (HIRc) or kinase-deficient human insulin receptors. When studied at the optimal growth stage for each cell line, insulin-stimulated responses measured in cells containing kinase-defective receptors with a Lys1018-Ala1018 substitution in the ATP-binding site of the kinase domain (A/K1018). Maximal insulin responsiveness for all these effects, measured as fold-increase over basal, was comparable in parental and HIRc cells (1.8- to 2.4-fold increases). Relative insulin responsiveness for all effects was greatest in A/K 1018 cells. One clone (AK-I) expressing a similar number of kinase-inactive receptors as in the HIRc cells displayed maximal responsiveness of 3.6- to 5.5-fold increases. A second A/K cell line containing 1/10 the number of kinase-inactive receptors displayed responsiveness intermediate between AK-I and parental or HIRc cells (1.5- to 4.8-fold increases). Both clones of kinase-deficient A/K1018 cells displayed impaired insulin sensitivity compared with HIRc cells. These findings suggest that expression of insulin receptor kinase activity is a determinant of insulin sensitivity but not necessarily of the final biological responsiveness of cells to insulin.

Inhibition of sodium-dependent L-leucine uptake in rat brain synaptosomes.

Synaptosomes isolated from adult rat cerebral cortices were used for studying the uptake of L-leucine by the Na(+)-dependent route. Three non-metabolizable amino acid analogues, which had been used previously to discriminate the Na(+)-dependent A-type uptake system of animal cells, were employed in this study. It was found that Na(+)-dependent uptake of leucine was insensitive to inhibition by 2-aminoisobutyric acid (AIB) and N-methylaminoisobutyric acid (MeAIB) whereas N-methylalanine (NMA) was markedly inhibitory. Inhibition by NMA was stereospecific--only the L-isomer had a pronounced effect. Na(+)-dependent uptake of leucine as well as its inhibition by L-NMA were rather insensitive to changes in pH from 6 to 9. Kinetic analysis of inhibition by L-NMA of Na(+)-dependent uptake revealed a non-competitive type of inhibition with a Ki value of approximately 0.5 mM.

Clopidogrel plus omeprazole compared with aspirin plus omeprazole for aspirin-induced symptomatic peptic ulcers/erosions with low to moderate bleeding/re-bleeding risk -- a single-blind, randomized controlled study.

BACKGROUND: Clopidogrel causes significantly less symptomatic peptic ulcer disease and gastrointestinal bleeding than low-dose aspirin in average-risk patients. The gastrotoxicity of clopidogrel in patients with active peptic ulcer disease is unknown. AIM: To compare the incidence of unhealed ulcers in patients receiving clopidogrel or aspirin. METHODS: Patients with aspirin-induced peptic ulcer disease treated with omeprazole (20 mg/day) were randomized to receive clopidogrel (75 mg/day) or to continue with low-dose aspirin. Success was defined as ulcer/erosion healing at the eighth week. RESULTS: One hundred and twenty-nine patients were recruited (69 received clopidogrel and 60 continued with aspirin). Thirty-one (45%) in the clopidogrel group and 25 (42%) in the aspirin group had a minor gastrointestinal bleed. No ulcer showed an adherent clot or visible vessel. The distributions of peptic ulcer disease were similar in the clopidogrel and aspirin groups (gastric ulcer: 41% vs. 40%; duodenal ulcer: 10% vs. 12%; gastric ulcer + duodenal ulcer: 6% vs. 3%; gastritis: 32% vs. 37%; duodenitis: 4% vs. 7%; gastritis + duodenitis: 0% vs. 2%). Clopidogrel and aspirin were re-started after 0.86 +/- 1.79 and 0.44 +/- 1.60 days, respectively (P = 0.170). Three (4%) patients stopped clopidogrel due to drug rash. Using per protocol analysis, the treatment success rates of clopidogrel and aspirin were 94% (62/66) and 95% (57/60), respectively. CONCLUSIONS: In patients with aspirin-associated peptic ulcer disease of low to moderate grade, both early conversion from aspirin to clopidogrel and continuation of aspirin are safe.

High incidence of clopidogrel-associated gastrointestinal bleeding in patients with previous peptic ulcer disease.

BACKGROUND: In average-risk patients, the new anti-platelet agent, clopidogrel, causes less upper gastrointestinal adverse events than aspirin. However, there are no safety data on the use of clopidogrel in high-risk patients. AIM: To evaluate the safety of clopidogrel in patients with peptic ulcer disease in a retrospective cohort longitudinal study. METHODS: During the period from January 2000 to May 2002, 70 patients who were prescribed clopidogrel (75 mg/day) for a previous history of non-aspirin-related peptic ulcer disease or a history of aspirin-related gastrointestinal complications (dyspepsia or peptic ulcer) were recruited. The occurrence of ulcer complications (bleeding/perforation/obstruction) was the primary end-point. RESULTS: After a median follow-up of 1 year, nine patients (12%) developed gastrointestinal bleeding and one had a perforated peptic ulcer. Clopidogrel-associated gastrointestinal bleeding was significantly more common in patients with a history of gastrointestinal bleeding than in those without (22% vs. 0%; P = 0.007; odds ratio, 1.3; 95% confidence interval, 1.1-1.5). CONCLUSIONS: Clopidogrel is associated with a high incidence of upper gastrointestinal bleeding in high-risk patients. A previous history of gastrointestinal bleeding appears to be a predictor of adverse gastrointestinal events.

Sequential intravenous/oral antibiotic vs. continuous intravenous antibiotic in the treatment of pyogenic liver abscess.

AIM: Pyogenic liver abscesses result in substantial morbidity and mortality. Antimicrobial regimens using sequential intravenous/oral therapy may reduce the length of hospital stay. In this retrospective analysis, the efficacy of continuous intravenous antibiotic therapy (group I) vs. sequential intravenous/oral antibiotic therapy (group II) was studied in patients with pyogenic liver abscess. METHODS: One hundred and twelve consecutive patients (55 in group I and 57 in group II) with pyogenic liver abscess were analysed. Clinical response, length of hospital stay and relapse rates were examined. RESULTS: Group II had a significantly shorter duration of intravenous antibiotic treatment (3.2 weeks vs. 5.9 weeks, P < 0.01) and a shorter length of hospital stay (28 days vs. 42 days, P < 0.01) when compared to group I. Oral antibiotics were prescribed for a median duration of 2.9 weeks in group II after discharge. No relapse occurred within 6 weeks after the completion of treatment in both groups. The cost of therapy was significantly lower in group II than in group I by 33%. CONCLUSIONS: A sequential intravenous/oral antibiotic regime is a safe and effective treatment for pyogenic liver abscess. This reduces the cost of therapy and the length of hospital stay.

A novel sodium-dependent uptake system for l-leucine in rat brain synaptosomes.

A novel Na(+)-dependent system for the uptake of l-leucine by rat brain synaptosomes is described. At a constant osmolarity of 270 mOsm/L, it functions optimally at a Na(+) concentration of 10 mM. This system is determined by measuring the difference in leucine uptake in the presence and absence of Na(+) as well as by measuring the residual uptake of leucine in the presence of an excess amount of 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid in a Na(+) -containing medium. Mg(2+) is found to enhance leucine uptake in the presence and absence of Na(+). However, its presence in the incubation medium reduces net leucine uptake rates due to Na(+) and also alters K(m) and V(max) values for the Na(+) -dependent uptake system.

Inhibition of sodium-dependent uptake processes in purified rat brain synaptosomes by Lophozozymus pictor toxin and palytoxin.

To get an insight into the mechanism of neurotoxicity exhibited by Lophozozymus pictor toxin (LPTX) and the toxin isolated from P.caribaeorum (C-PTX) studies were carried out on the effect of these toxins on the uptake of selected substrates (neurotransmitters, amino acids and glucose) in isolated nerve endings. The toxins were found to inhibit the uptake of gamma-aminobutyric acid (GABA), noradrenaline, choline, L-leucine and 2-deoxy-D-glucose in rat brain synaptosomes. LPTX- or C-PTX-induced inhibition of synaptosomal uptake was reduced in the absence of Na+ in the assay medium. Synaptosomes exposed to LPTX and C-PTX release K+ in a dose-dependent manner. Ouabain, a selective inhibitor of the plasma membrane Na+, K(+)-ATPase could inhibit LPTX- and C-PTX-induced K+ efflux from synaptosomes and alleviate the toxin-induced inhibition of synaptosomal GABA uptake. It appears that the induction of ionic flux is the primary cause of toxicity by these toxins leading to the inhibition of Na(+)-dependent uptake processes in synaptosomes. The antagonistic action of ouabain suggests the involvement of the membrane sodium pump in the development of cytotoxicity.

Skip colonic ulceration in typhoid ileo-colitis.

Colonic skip lesions are typically described in Crohn's colitis, but this phenomenon has been recognized in ulcerative colitis (skipped appendiceal involvement), Behcet's colitis, cytomegaloviral colitis, and even in Aeromonas hydrophilia and Histoplasma capsulatum infection. However, skip lesions in typhoid ileo-colitis have not been reported in the English-language literature. We report herein a patient with skip ulcers due to typhoid fever.

Bioactivity and mechanism of action of Lophozozymus pictor toxin.

The bioactivity of Lophozozymus pictor toxin (LPTX) and the possible mechanism of action of the purified toxin are described. LPTX is found to possess palytoxin-like bioactivities. Besides exhibiting cytotoxic and haemolytic properties, LPTX causes the release of K+ from erythrocytes and inhibits 2-[14C]deoxy-D-glucose uptake into HeLa cells. Although LPTX acts on HeLa cell and erythrocyte membranes, it does not interact with mitochondrial or liposomal membranes containing different phospholipid compositions. Ouabain, but not sphingomyelin, is able to prevent the toxic effects of LPTX. This antagonistic effect of ouabain on LPTX suggests that the toxin might mediate its toxic effects via the membrane Na+/K(+)-ATPase but not through interaction with membrane lipids.

Effect of simethicone on the accuracy of the rapid urease test.

OBJECTIVE: Simethicone, which is a principal ingredient in the defoaming agent used during gastroscopy, can inhibit the growth of Helicobacter pylori (MIC, 64-128 mg/l). This prospective study was designed to evaluate the in vivo and in vitro effects of simethicone on the accuracy of the rapid urease test (RUT). METHODS: In the in vivo study, three sets of gastric biopsies (two from the antrum, and one from the corpus) were taken from 75 patients. The first set was examined histologically, and the second set was used for the RUT (pre-simethicone RUT). Then, 25 ml simethicone (1200 mg/l) was introduced into the stomach for a contact time of 1 min. A third set of gastric biopsies was taken for the RUT (post-simethicone RUT). In the in vitro clinical study, 41 patients were recruited. The first set of gastric biopsies was used for the RUT (pre-incubation RUT). The second set was incubated in 1 ml of simethicone for 5 min before being used for the RUT (post-incubation RUT). In the spectrophotometric study, urease activity before and after incubation in simethicone for 5 min was quantified in 12 patients by measuring the absorbance at 560 nm. RESULTS: Reading at 15 min, the concordance rate between the pre-simethicone and post-simethicone RUT was 98%. In the in vitro clinical study, the concordance rate between the pre-incubation and post-incubation RUT was 97%. The spectophotometric study showed a significant reduction of 43% in urease activity after incubation in simethicone. CONCLUSION: The application of a defoaming agent containing simethicone does not affect the accuracy of the RUT. However, simethicone modestly suppresses urea hydrolysis.

Lower intestinal hemorrhage due to a dislodged metallic stent.

A case of a 72 year old man is reported who developed a choledochoduodenal fistula due to distal biliary obstruction by a tumor of the papilla. A metal stent, introduced through this fistula into the common bile duct, dislodged and passed spontaneously with the feces. Plastic stents were then successfully inserted.

High and low affinity transport of L-arginine in rat brain synaptosomes.

The uptake of L-arginine into purified rat brain synaptosomes was investigated with respect to time and various concentrations of L-[3H]arginine. Specific uptake was found to be linear with time for up to 5 min of incubation at 37 degrees C. Electrolytes, including sodium chloride, potassium chloride, magnesium chloride and calcium chloride, inhibited uptake of 3 microM L-arginine, and the inhibitory effect increased with increased electrolyte concentration under constant osmolarity. It was found that L-arginine was transported into synaptosomes by two uptake components--a high affinity component (3.5 microM) and a low affinity component (100 microM). These two components were similar to the Ly+ system because of their extreme sensitivity to inhibition by L-lysine and L-ornithine but were distinguishable from each other by kinetic analysis of the uptake data and by their relative sensitivity to inhibition by several amino acids.

Storage temperature of the unbuffered rapid urease test.

OBJECTIVES: The unbuffered rapid urease test (RUT) is an accurate, rapid, and inexpensive method for detecting Helicobacter pylori. However, it is generally recommended that the reagent be prepared daily. This prospective study was undertaken to evaluate the shelf life of our unbuffered RUT when stored at 4 and -20 degrees C. METHODS: Ninety-five patients were studied. Three sets of antral (X2) and body (X1) biopsy samples were taken from each patient. The samples were subjected to histological examination, with the RUTs stored at 4 and -20 degrees C. The RUT tubes were examined at 1 and 15 min. RESULTS: Fifty-six patients (59%) were infected with H. pylori as defined by histological examination. The reagent was classified according to storage time (group I, < or = 5 days; group II, > 5 days). The mean (SD) storage time of group I (n = 59) and group II (n = 36) was 3.2 (1.4) and 9.9 (5.0) days, respectively. At 15 min, the sensitivity of our RUT stored at 4 degrees C was significantly higher in group I than in group II (92 vs 47%). On the other hand, the sensitivity of our RUT stored at -20 degrees C remained consistently high in both groups (15 min: group I, 92%; group II, 100%). Our RUTs stored at 4 and -20 degrees C were highly specific in both groups. CONCLUSIONS: Our RUT remains highly sensitive and specific when it is stored at 4 degrees C for up to 5 days. When the RUT is expected to be stored for a longer period of time, the bottles should be frozen at -20 degrees C.