Preliminary results using ultrasound transmission for image-guided thermal therapy

The feasibility of using an acoustic camera as a real-time imaging device for thermal surgery was investigated. The study compares camera images of tissue samples taken before, during and after a volume of tissue was thermally coagulated using focused ultrasound (US). This apparatus has analogous acoustic counterparts to an optical charge couple device (CCD) camera. The setup was operated in transmission mode, with a tissue sample placed between the camera and a 10-MHz illuminating transducer. A high-intensity continuous-wave US signal from a therapeutic transducer was focused inside the sample tissue. A reversible, time-dependent variation in image intensity was observed in the region of the therapeutic sonications in all tissues tested: bovine fat and porcine and rabbit livers. Correlations between image intensities and temperatures were shown; rabbit liver resulted in a correlation coefficient (R(2)) of 0.6694 and bovine fat resulted in an R(2) of 0.9455. When temperatures high enough to coagulate tissue were reached, permanent changes in the images were observed. Lesion locations and dimensions from the images were found to be comparable to the sectioned tissue samples. An R(2) of 0.919 resulted when lesion size detected from the camera was compared to the actual lesion size. Preliminary results may indicate that the camera has an application for monitoring thermal surgery.

Usefulness of MR imaging-derived thermometry and dosimetry in determining the threshold for tissue damage induced by thermal surgery in rabbits

PURPOSE

To investigate in vivo the feasibility of using magnetic resonance (MR) imaging-derived temperature and thermal dose measurements to find the threshold of thermal tissue damage.

MATERIALS AND METHODS

Sonications were delivered in rabbit thigh muscles at varying powers. Temperature-sensitive MR images obtained during the sonications were used to estimate the temperature and thermal dose. The temperature, thermal dose, and applied power were then correlated to the occurrence of tissue damage observed on postsonication images. An eight-element phased-array transducer was used to produce spatially flat temperature profiles that allowed for averaging to reduce the effects of noise and the voxel size.

RESULTS

The occurrence of tissue damage correlated well with the MR imaging-derived temperature and thermal dose measurements but not with the applied power. Tissue damage occurred at all locations with temperatures greater than 50.4 degrees C and thermal doses greater than 31.2 equivalent minutes at 43.0 degrees C. No tissue damage occurred when these values were less than 47.2 degrees C and 4.3 equivalent minutes.

CONCLUSION

MR imaging thermometry and dosimetry provide an index to predict the threshold for tissue damage in vivo. This index offers improved online control over minimally invasive thermal treatments and should allow for more accurate target volume coagulation.

Early human T cell activation events with engagement of surface MHC class II

Major histocompatibility complex (MHC) class II are expressed on most activated human lymphocytes. They direct antigen presentation events in dendritic cells and B cells (collectively called antigen presenting cells), but the role for MHC class II in human T cells is not well understood. To understand the role of surface MHC class II and to identify the molecules involved in signaling, we have defined the early activation sequence in T cells when MHC class II are engaged by a specific antibody. Specifically, we have characterized the involvement of phosphotyrosine kinases, phospholipase C (PLC), and Ca2+ mobilization. With the engagement by either whole anti-class II antibody or its Fab fragments, the enzymatic activity of p56lck and ZAP-70 increased, but there was no increase in p59fyn activity. In addition, the intracellular free Ca2+ increased, which was due to enhanced influx and not to the mobilization of intracytoplasmic Ca2+. These events did not require cross-linking because they were not significantly augmented by the addition of antispecies antibody. The coimmunoprecipitation of tyrosine phosphorylated PLC-gamma1 with surface MHC class II suggested that PLC-gamma1 could be recruited to MHC class II after engagement. These results show the complexities of the early signals transduced by the engagement of surface MHC class II on T cells.

Brefeldin A-induced alterations in processing of MHC class II-Ii complex depend upon microtubular function

The role of microtubules in the brefeldin A (BFA)-associated relocation of major histocompatibility complex (MHC) class II alphabeta chains (alphabeta) and the invariant chain (Ii) was characterized in Raji cells by the use of nocodazole (ND). BFA blocked the transport of alphabeta Ii proteins through the Golgi and redistributed them to the endoplasmic reticulum (ER) along with Golgi-resident enzymes. The result of the colocalization of processing enzymes and newly synthesized proteins was a downshift of alphabeta Ii molecular weight (MW) of 2 kDa, and their resistance to endoglycosidase H (endo H) after 6 hr of chase. ND by itself had no effect on the processing and transport of alphabeta to the cell surface. The addition of ND to BFA-treated cells downshifted alphabeta Ii by 4 kDa. Additionally, alphabeta Ii proteins remained sensitive to neuraminidase after 16 hr of chase. In vitro alpha-mannosidase treatment of immunoprecipitated alphabeta Ii generated a similar 4-kDa downshift of MW. Either 1-deoxymannojirimycin (DJN) or swainsonine (SWN) blocked the MW downshift caused by BFA + ND treatment. These observations indicated that in Raji cells, most of the BFA-associated relocations of cis-, medial Golgi proteins, and the addition of sialic acid from the trans-Golgi were microtubule-independent. The retrograde transport of the medial Golgi enzyme N-acetylglucosamine transferase, however, required microtubular function. Microtubule disrupters could affect BFA treatment of viral infections by further disrupting viral protein processing.

An analysis of exam room utilization in U.S. medical schools

Examination room utilization in U.S. academic practices has not generally included clinical space used in the teaching of medicine. The lack of planning guidelines at some medical schools for examination room space may have them operating inefficiently by as much as 50 percent or 60 percent. Not having guidelines may be causing medical schools to commit valuable resources to develop unnecessary space. A survey of 126 U.S. medical schools determined their estimated maximum annual examination room visit capacity at 40 percent to 50 percent of their EMAERVC during the study period yet planned to add examination room capacity.

Effects of nonsteroidal antiinflammatory drugs on ulcerogenesis and gastric secretion in pylorus-ligated rat

The effects of nonsteroidal antiinflammatory drugs on ulcerogenesis and gastric secretion were evaluated in a pylorus-ligated rat model. Oral administration of salicylate (50 mg/kg), aspirin (50 mg/kg), and indomethacin (3.5 mg/kg) significantly increased ulcerogenesis over the basal value by six- to sevenfold, but ibuprofen's (10 mg/kg) fourfold increase was not significant. Aspirin in conjunction with histamine (0.5 mg/kg subcutaneously) significantly increased ulcerogenesis by 2.7-fold compared to histamine alone. Basal acid secretion was increased significantly by 156% after indomethacin, but not by other nonsteroidal antiinflammatory drugs. In contrast, all nonsteroidal antiinflammatory drugs, except indomethacin, significantly decreased histamine-stimulated acid secretion. Non-steroidal antiinflammatory drugs had no effect on pepsinogen secretion. Ranitidine pretreatment (25 mg/kg intraperitoneally) significantly decreased basal acid and pepsinogen secretion in all treatment groups by > 85% and > 40%, respectively, and ulcerations induced by salicylate, aspirin, and indomethacin were also inhibited by 90%, 60%, and 60%, respectively. The observed inhibition of prostaglandin E2 generation by nonsteroidal antiinflammatory drugs under basal secretory conditions appeared to correlate with the extent of ulcerogenesis. Our data support the concept that acid, in addition to inhibition of prostaglandin E2 synthesis, plays an important role in the pathogenesis of nonsteroidal antiinflammatory drug-induced gastropathy.

Prohibitin expression during cellular senescence of human diploid fibroblasts

Prohibitin is an evolutionarily conserved gene postulated to possess tumor suppressor activity and to contribute to the limited lifespan of human diploid fibroblast-like cells. Prohibitin mRNA and protein expression and its ability to become post-translationally modified were determined in human diploid fibroblast-like cells of different in vitro ages. The expression of prohibitin mRNA and protein changes little with increasing in vitro age; however, its protein product is post-synthetically modified in younger but not older cells. These results suggest that prohibitin is similar to the retinoblastoma gene product whose anti-proliferative activity remains active in older cells because it is not post-synthetically modified.

Nonsalicylate nonsteroidal antiinflammatory drugs augment prestimulated acid secretion in rabbit parietal cells. Investigation of the mechanisms of action

The effects of nonsalicylate nonsteroidal antiinflammatory drugs on acid secretion were studied in isolated rabbit parietal cells. Indomethacin, naproxen, and carprofen (10(-6)-10(-4) mol/L) potentiated histamine-, forskolin-, 3-isobutyl-1-methylxanthine-, and dibutyryl cyclic adenosine monophosphate-stimulated acid secretion without affecting basal acid secretion. This augmentation of secretagogue-stimulated acid secretion was dependent on extracellular calcium because potentiation was abolished by calcium depletion of the medium or in the presence of the calcium antagonist lanthanum chloride. Potentiation was independent of the H2 and muscarinic receptors and did not appear to involve guanine nucleotide regulatory proteins. Proton pump activity was unaffected by indomethacin. Furthermore, nonsteroidal antiinflammatory drugs increased calcium efflux through the plasma membrane, as measured by calcium 45, and decreased endogenous prostaglandin E2 content. Exogenous dimethyl prostaglandin E2 inhibited the potentiating effect of these drugs on histamine-stimulated but apparently not on dibutyryl cyclic adenosine monophosphate-stimulated acid secretion. The data indicate that nonsalicylate nonsteroidal antiinflammatory drugs interacted at a postreceptor site between adenylate cyclase and the proton pump. The potentiating effects of these drugs were regulated by calcium and possibly modulated by prostanoids.

Aspirin potentiates prestimulated acid secretion and mobilizes intracellular calcium in rabbit parietal cells

The effects of aspirin on gastric acid secretion were studied in isolated rabbit parietal cells (PC). Aspirin (10(-5) M) potentiated histamine-, dibutyryl cyclic AMP (dbcAMP)-, forskolin- and 3-isobutyl-1-methylxanthine-stimulated acid secretion without affecting basal acid secretion. Augmentation of secretagogue-stimulated acid secretion by aspirin was dependent on calcium (Ca2+) since potentiation was blocked by removal of extracellular Ca2+ ([Ca2+]o) or addition of the calcium antagonist lanthanum chloride. Using the Ca2+ probe fura-2, aspirin (10(-6) - 2 X 10(-5) M) rapidly increased intracellular free Ca2+ concentration ([Ca2+]i) in a dose-dependent manner. The source of released Ca2+ was intracellular as demonstrated by depletion of intracellular Ca2+ and [Ca2+]o with EGTA washing. Aspirin did not affect several other signal transduction sites involved in stimulus-secretion coupling, including the H2 receptor, intracellular cyclic AMP (cAMP), inositol 1,4,5, triphosphate (IP3) and H+,K(+)-ATPase. Aspirin decreased PC prostaglandin E2 (PGE2) content by 98%. Exogenous dimethyl PGE2 (dmPGE2) inhibited both histamine-stimulated acid secretion and its enhancement by aspirin. In contrast, dmPGE2 abolished aspirin-induced potentiation of dbcAMP-stimulated acid secretion by augmenting the dbcAMP-stimulated response. These results indicate that aspirin acts at a site beyond the adenylate cyclase/cAMP system and before the proton pump, presumably by releasing Ca2+ from an IP3-independent intracellular storage pool and by inhibiting PGE2 generation.

Mechanisms of gastric proton pump inhibition by calcium channel antagonists

The inhibitory effects of Ca channel antagonists on gastric acid secretion [[14C]-aminopyrine (AP) uptake ratio] have been analyzed in isolated rabbit parletal cells (PC). Secretagogue-stimulated AP uptake was inhibited by verapamil and diltiazem in a dose-dependent manner with IC50 values of 15 and 100 microM, respectively, both in the presence and absence of extracellular Ca. In contrast, nifedipine had no effect on AP accumulation. Verapamil decreased histamine-stimulated respiration with the same IC50 as observed for AP uptake. Imidazole, a weak base, by buffering the acid spaces in PC, reversed the inhibitory effect of verapamil on respiration. In the bullfrog gastric mucosa, forskolin-stimulated proton transport was inhibited by verapamil (10(-4) M) from the luminal but not the serosal side. This inhibitory effect was reversed by either elevating KCl concentration in, or removing the drug from, the secretory solution. Verapamil inhibited gastric microsomal H+,K(+)-adenosine triphosphatase (H+,K(+)-ATPase) and PC K(+)-stimulated p-nitrophenyl phosphatase activities with a higher potency than diltiazem. Inhibition of these enzymes by verapamil and diltiazem was pH dependent. The drugs competed with K+ in both H+,K(+)-ATPase and K(+)-stimulated p-nitrophenyl phosphatase reactions. Our data suggest that inhibition of the gastric proton pump by verapamil or diltiazem is not due to their Ca channel antagonism but to their interaction with the luminal high affinity K(+)-site of the H+,K(+)-ATPase under acidic conditions.

Stimulation of mono (ADP-ribosyl)ation by reduced extracellular calcium levels in human fibroblasts

Lowering extracellular calcium in cultures of human diploid fibroblast-like cells caused a rapid depletion of NAD pools. This loss of NAD was reversed by restoring extracellular Ca2+ and was inhibited by 3-aminobenzamide, an inhibitor of ADP-ribosyl transfer reactions. The concentrations of 3-aminobenzamide needed to inhibit the loss of NAD were consistent with those required to inhibit cellular mono(ADP-ribosyl) rather than poly(ADP-ribosyl) reactions. Calcium depletion did not inhibit the biosynthesis of NAD. These results suggest that mono(ADP-ribosyl)ation is involved in the regulation of cellular Ca2+ levels.

Effectiveness of publicity campaign encouraging earlier referral of hearing loss in adults

During 16,070 consultations in general practice 70 adults complained of difficulty with hearing. A simple poster displayed in the waiting areas together with an accompanying leaflet almost doubled the incidence of presentation of loss of hearing. Nevertheless, more than half of those complaining had failed to notice the prominently displayed personally relevant message, and the beneficial effect was lost almost as soon as the poster was removed.

Fluorescent color factor calculation using dBASE-II

A software system utilizing dBASE-II operating on a dual-drive Apple II+ computer is described. Color factors and retention times for 15 amino acids and epsilon-(gamma-glutamyl)lysine dipeptide are calculated following high performance liquid chromatography. The software package produces a listing of acceptable limits for these parameters calculated as plus and minus 2 standard deviations of the mean. The code is distributed in source form.

Use of videotape and phone teleconference in statewide extension program on milk quality and mastitis control

Extension specialists used a 3-h videotape and phone teleconferences to teach dairy farmers how to produce quality milk and control mastitis. This 5-d effort reached approximately 20% of the state's commercial dairy farms in 22 meetings at 22 locations. A survey of approximately 170 dairy producers indicated those attending the program had less education, were younger, and more were enrolled in Dairy Herd Improvement program as compared with the average Maryland dairy farmer. Eighty percent reported they would like to see additional videotaped programs; 5% indicated no interest in viewing other topics on videotape. Scores on knowledge pretests and posttests were 66 and 76%, respectively. Only 1.7% were using all 13 mastitis management practices recommended in the educational program, and 11.2% said they would use all 13 practices after participating in the program.

A method of assessment during vocational training: report of a pilot study

Problems arising from the present rate of failure of vocational trainees in the MRCGP examination are outlined; and the role of formative assessment during training in reducing this rate is considered. A study is described in which trainees in a number of centres were assessed by a method designed to measure specified cognitive abilities and areas of knowledge. The method, based on written papers, provides each candidate with a profile of performance and generates comparative standards. Reliability of marking, the distribution of candidate-scores within and between areas of assessment and techniques for monitoring the effectiveness of questions are reported. Use of the method by College as an educational service to trainees is considered, along with its potential as a Part I MRCGP examination.

Isolation and identification of dihydrocitrinone, a urinary metabolite of citrinin in rats

Dihydrocitrinone, 3,4-dihydro-6,8-dihydroxy-3,4,5-trimethylisocoumarin-7-carboxylic acid, was isolated and identified as a urinary metabolite after oral administration of citrinin to rats. Male and female Osborne-Mendel rats received 30 mg citrinin/kg body weight by oral intubation. The metabolite dihydrocitrinone was present in urine collected at 0-2, 2-4, 4-6, 6-8, and 8-24 h after treatment. Only unchanged citrinin was found in blood collected 24 h after administration of the compound. The metabolite had a blue fluorescence and the same Rf on thin-layer chromatography, the same retention time on reverse-phase high-pressure liquid chromatography, and the same mass spectrum as an authentic sample of dihydrocitrinone.

Differences in the distribution of phosphate content in the ribosomal subunit proteins of free and membrane-bound ribosomes from normal and regenerating rat liver

Proteins of membrane-bound ribosomes from normal liver contained 60-70% more phosphate than did proteins from free ribosomes. This difference was not a reflection of the phosphate contents of respective 40 S subunits. Instead, it was owing to the presence of high levels of phosphorylated proteins in the 60 S subunits, i.e., phosphate contents equal to or greater than those for 40 S subunits. The proteins of membrane-bound 60 S subunits contained twice the phosphate as free 60 S subunits. In regenerating rat liver, membrane-bound ribosomes had increased phosphate in the proteins of the 40 S subunits and decreased phosphate in proteins of the 60 S subunit when compared to controls for normal rat liver. No significant changes occurred in the proteins of free ribosomes from regenerating rat liver. These findings are discussed with respect to (a) the importance of assessing total phosphate contents of proteins in the study of ribosomal protein phosphorylation, and (b) the possible involvement of ribosomal protein phosphorylation in the segregation of ribosomes into free and membrane-bound populations and the regulation of these distributions to meet changes in the translational demands of the cell.

Exposure of girls to oestrogens during fetal development. Report of a survey of maternal records

In a two-partner practice with 5,000 patients where oestrogens had never been prescribed during pregnancy, it was found on examining the records, that at least eight girls had been exposed to oestrogens in utero, two of them to stilboestrol. Three of them have since been examined with negative results. In a quarter of cases no information was available from the records.

A preliminary report on the supraoptic nucleus and control of intraocular pressure

Four animals received unilateral optic nerve sections which ablated that eye's rise in intraocular pressure in response to water drinking. Bilateral supraoptic nucleus lesions in two animals resulted in ablation of the other eye's response to water drinking. Both animals showed histopathologic proof of the lesion site. Two animals received sham operations for the supraoptic nucleus lesions with no change in their differential response to water drinking. This report gives preliminary evidence of the hypothesis of a supraoptic nuclear control mechanism of intraocular pressure.