[Epidemiological investigation on the local epidemic situation in Zhengzhou High-Tech Zone caused by SARS-CoV-2 Delta variant].

This study collected epidemic data of COVID-19 in Zhengzhou from January 1 to January 20 in 2022. The epidemiological characteristics of the local epidemic in Zhengzhou High-tech Zone caused by the SARS-CoV-2 Delta variant were analyzed through epidemiological survey and big data analysis, which could provide a scientific basis for the prevention and control of the Delta variant. In detail, a total of 276 close contacts and 599 secondary close contacts were found in this study. The attack rate of close contacts and secondary close contacts was 5.43% (15/276) and 0.17% (1/599), respectively. There were 10 confirmed cases associated with the chain of transmission. Among them, the attack rates in close contacts of the first, second, third, fourth and fifth generation cases were 20.00% (5/25), 17.86% (5/28), 0.72% (1/139) and 14.81% (4/27), 0 (0/57), respectively. The attack rates in close contacts after sharing rooms/beds, having meals, having neighbor contacts, sharing vehicles with the patients, having same space contacts, and having work contacts were 26.67%, 9.10%, 8.33%, 4.55%, 1.43%, and 0 respectively. Collectively, the local epidemic situation in Zhengzhou High-tech Zone has an obvious family cluster. Prevention and control work should focus on decreasing family clusters of cases and community transmission.

[Research and exploration of salivary biological markers for hepatitis B-related hepatocellular carcinoma].

Objective: To study using isotope-labeled relative and absolute quantitative proteomics methodologies to screen for salivary biological markers as a simple, non-invasive tool for identifying hepatitis B-related HCC at an early stage. Methods: Saliva samples were collected to extract salivary proteins. Isotope-labeled relative and absolute quantitative proteomics were used to analyze the differentially expressed proteins between the hepatocellular carcinoma (HCC) and non-HCC groups. Western blotting, immunohistochemistry, and enzyme-linked immunosorbent assays were used to verify differential proteins and identify markers in liver cancer tissues and saliva. Statistical analysis was used to analyze the diagnostic efficiency of salivary biomarkers. Results: 152 differentially expressed salivary proteins were screened out between the HCC and non-HCC groups. Western blot, immunohistochemistry, and enzyme-linked immunosorbent assays validated that the expressions of α-1-acid glycoprotein 1 (ORM1) and alpha-fetoprotein (AFP) were significantly increased in HCC (P < 0.05). There was a significant correlation between salivary AFP and serum AFP (P < 0.05). HCC was diagnosed when salivary α-1-acid glycoprotein 1 combined with AFP. The area under the receiver operating characteristic curve was 0.8726 (95% confidence interval: 0.8104 ~ 0.9347), the sensitivity was 78.3%, and the specificity was 88%. Conclusion: Salivary AFP and α-1-acid glycoprotein 1 can serve as potential biomarkers for hepatitis B-related hepatocellular carcinoma.

[Constructions of the scale of difficulty in the extraction of impacted mandibular third molars by using Delphi method].

OBJECTIVE: To evaluate the relevant indicators affecting difficulty in the extraction of impacted mandibular third molars and score difficulty of different operation and risk indicators, so as to build an intuitive and accurate scale to help operators make more accurate analysis and prediction of difficulty before the operation. METHODS: Based on literature and the clinical review, the difficulty indicators of tooth extraction were summarized. Firstly, 10 doctors from Peking University School and Hospital of Stomatology who had been engaged in alveolar surgery for a long time established an expert nominal group, and then rated whether the summarized indicators needed to be retained in the form of face-to-face questionnaires. A level 1 and 2 item frame for evaluating difficulty in the tooth extraction was formed after discussion; Then Delphi method was used to send a questionnaire to 30 experts by e-mail. After two rounds of scoring and modification, the scale of difficulty in the extraction of impacted mandibular third molars was formed. RESULTS: The recycling rate of two rounds of questionnaires was 100.0%, which showed that the experts were very enthusiastic about the study; The authority coefficients (Cr) of the two rounds of Delphi expert consultation were both 0.92, which showed that the results were representative and authoritative. After two rounds of grading and revision, the variable coefficient (CV) decreased and the Kendall's concordance coefficient (W) increased, which were statistically significant: In the first round, the CV was 0.24 and W was 0.56 (P < 0.001), and in the second, the CV was 0.19 and W was 0.72 (P < 0.001), which indicated that there was a good convergence among the expert opinions. Finally, a scale of difficulty in the tooth extraction containing 12 items at level A and 37 items at level B was formed, including operation difficulty indicators, risk difficulty indicators and common difficulty indicators. CONCLUSION: Based on comprehensive literature retrieval, the study has put forward the concept that difficulty in the extraction of impacted mandibular third molars is composed of operation difficulty and risk difficulty. Using Delphi method, the long-term clinical experience and professional knowledge of experts are transformed into quantitative indicators as a scoring scale. The scale has certain representativeness and authority.

[Application of pretrained model based on electronic medical record in recognition of acute respiratory infection].

Objective: To evaluate the recognition of acute respiratory infection (ARI) by a pretrained model based on electronic medical records (EMRs). Methods: 38 581 EMRs were obtained from Chongqing University Three Gorges Hospital in December 2021. Bidirectional encoder representation from transformers (BERT) pretrained model was used to identify ARI in EMRs. The results of medical professionals were considered as the gold standard to calculate the sensitivity, specificity, Kappa value, and area under the curve of the receiver operating characteristic (AUC). Results: There were 3 817 EMRs in the test set, with 1 200 ARIs. A total of 1 205 cases were determined as ARI by the model, with a sensitivity of 92.67% (1 112/1 200) and a specificity of 96.45% (2 524/2 617). The model identified ARI with similar accuracy in males and females (AUCs 0.95 and 0.94, respectively), and was more accurate in identifying ARI cases in those aged less than 18 than in adults 18-59 and adults 60 and older (AUCs 0.94, 0.89 and 0.94, respectively). The current model had a better identification of ARIs in outpatient patients than that in hospitalized patients, with AUCs of 0.74 and 0.95, respectively. Conclusion: The use of the BERT pretrained model based on EMRs has a good performance in the recognition of ARI cases, especially for the outpatients and juveniles. It shows a great potential to be applied to the monitoring of ARI cases in medical institutions.

Computer-aided three-dimensional assessment of periodontal healing distal to the mandibular second molar after coronectomy of the mandibular third molar: a prospective study.

BACKGROUND: The periodontal healing distal to the mandibular second molar (M2M) after coronectomy of the M3M has shown controversial results. We aimed to combine a digital method with cone-beam computed tomography (CBCT) and estimate periodontal healing of M2M after M3M coronectomy. An accurate and stable indicator in three dimensions was also explored tentatively. METHODS: Patients with a M3M in contact with the inferior alveolar canal were included. CBCT was applied immediately after coronectomy (baseline) and 6-months later. Data were investigated with digital software for registration. Previously reported and coronectomy-related factors were included for univariate and multivariate analyses. RESULTS: A total of 181 patients (213 M3Ms) completed 6-month follow-up. Significant reduction in the distal intra-bony defect (DBD) depth of the M2M was shown (1.28 ± 1.24 mm, P < 0.001). DBD depth of the M2M at baseline was the most influential factor (r = 0.59), followed by preoperative M3M condition, age, rotation and migration of the root complex. Remaining enamel (OR = 6.93) and small retromolar space (0.67) contributed to re-contact of the root complex and M2M. Bone volume regenerated in the distal 2 mm was associated significantly with DBD-depth reduction (r = 0.74, P < 0.001). CONCLUSIONS: Bone volume regenerated in the distal 2 mm of the M2M denoted stability of distal periodontal healing of the M2M. DBD depth at baseline was the most influential factor for healing of a DBD of the M2M after M3M coronectomy. The remaining enamel and a small retromolar space could contribute to re-contact of the root complex and the M2M. TRIAL REGISTRATION: China Clinical Trial Center, ChiCTR1800014862 . Registered 10 February 2018.

The complete genomic sequence of Sugarcane mosaic virus from Canna spp. in China.

BACKGROUND: Sugarcane mosaic virus (SCMV) is the prevalent virus inducing maize dwarf mosaic and sugarcane mosaic diseases in China. According to the phylogenetic results of the complete genomic and coat protein gene sequences, SCMV was divided into four or five molecular groups, respectively. Previously, we detected SCMV isolates of group SO from Canna spp. in Ji'nan, Shandong province, China. FINDINGS: In this study, we collected two SCMV isolates infecting Canna spp. in Ji'nan (Canna-Ji'nan) and Tai'an (Canna-Tai'an) of Shandong, China. Their complete genome sequences had genome of 9576 nucleotides and contained a large open reading frame encoding a polyprotein of 3063 amino acids. The phylogenetic analysis showed that the both Canna-Ji'nan and Canna-Tai'an were clustered into an independent group based on the complete genome sequence. CONCLUSION: In this study, we report the complete genome sequences of SCMV infecting Canna spp. from Ji'nan and Tai'an. This is the first report on SCMV belonging to SO group.

Methylmercury-l-Cysteine targeting L-type amino acid transporter conjugate cytotoxicity on C6 glioma cells.

Glioma is the most common primary tumor in the brain, accounting for about 40~50% of intracranial primary tumors. Most chemotherapeutic drugs have difficulty in penetrating the blood-brain barrier, and their clinical applications are greatly limited. We evaluated the effects of methylmercury-L-cysteine (MeHg-L-cys) and methylmercury chloride (MMC) on apoptosis of C6 glioma cells. L-type amino acid transporter (LAT1) was used to investigate the targeted transport function and cytotoxicity of MeHg- L-cys in glioma. MeHg-L-cys enhanced the ability of targeting glioma cells and reduced the adverse reactions to normal brain tissues. Therefore, it is significantly important to develop new anti-glioma drugs targeting the blood-brain barrier.

[Timeless promotes the proliferation of hepatocellular carcinoma cell by reprogramming of glucose metabolism].

Objective: To explore the function and molecular mechanism of Timeless in promoting hepatocellular carcinoma (HCC) growth. Methods: The expression of Timeless in HCC and paracancer tissues were analyzed by using the public data of HCC. Timeless was overexpressed in MHCC97L cells and silenced in MHCC97H cells, respectively, and the expression of Timeless and its downstream molecules were detected by real-time PCR and western blot. The effects of Timeless on cell glycolysis, oxidative phosphorylation and proliferation were detected by the glucose uptake experiment, lactic acid detection experiment, the extracellular fluid pH detection experiment, cell oxygen consumption test and cell viability assay, respectively. Results: The level of Timeless in HCC tissue was significantly higher than that of paracancer tissue (P<0.05). The relative cellular glucose uptake levels in the groups of Timeless knockdown, including siTimeless-1 and siTimeless-2 group were 0.510±0.119 and 0.508±0.099, respectively, significantly different from that of control group (P<0.05); The relative cellular uptake level of Timeless overexpressed group was 1.953±0.324, significantly different from that of vector transfected group (P<0.05). The relative levels of lactic acid production in the siTimeless-1 and siTimeless-2 group were 0.579±0.096 and 0.550±0.120, respectively, significantly different from that of control group (P<0.05); The relative production level of lactic acid in the Timeless overexpressed group was 1.463±0.179, significantly different that of vector transfected group (P<0.05). The extracellular pH values of siTimeless-1 and siTimeless-2 group were 7.390±0.035 and 7.370±0.060, respectively, significantly different from that of control group (P<0.05); the extracellular pH value of Timeless overexpressed group was 7.130±0.031, significantly different than vector transfected group (P<0.05). Oxygen consumption rate of siTimeless-1 and siTimeless-2 group were 3.686±0.389 and 3.955±0.431, respectively, significantly higher than 1.690±0.297 of control group (P<0.05); Oxygen consumption rate of Timeless overexpressed group was 1.302±0.336, significantly lower than 3.185±0.262 of vector transfected group (P<0.05) Timeless inhibited the expression of p53. The cell glucose uptake, lactic acid production, the pH of extracellular culture medium and cell oxygen consumption of control group were not significantly different from that of Timeless and p53 co-silenced group [(si-Timeless+sip53) group] (P>0.05); the glucose uptake, the production of lactic acid, the pH of the extracellular culture medium and the oxygen consumption of Timeless co-transfected with p53 (Timeless+p53) group were not significantly different from those of vector transfected group (P>0.05). Timeless promoted the proliferation of HCC cells through inhibiting the expression of p53. Conclusion: Timeless promotes reprogramming of glucose metabolism and proliferation of HCC cells by inhibiting the p53-dependent signaling pathway.

[LincRNA-ROR functions as a ceRNA to regulate Oct4, Sox2, and Nanog expression by sponging miR-145 and its effect on biologic characteristics of colonic cancer stem cells].

Objective: To investigate the impact of lincRNA-ROR, a ceRNA by binding miR-145 on the expression of the downstream genes Oct4, Sox2 and Nanog, and related biological characteristics of colon cancer stem cells, and to elucidate the clinical significance of this molecular regulatory network. Methods: Fifty-two cases of colorectal cancer tissue and adjacent tissue were collected at Nanyang City Central Hospital and Nanyang Second Hospital, Henan Province, from 2014 to 2016. Real-time quantitative polymerase chain reaction (qPCR) was used to detect the expression of lincRNA-ROR and miR-145 in colorectal cancer tissue and isolated colon cancer cells. The correlation between the expression of lincRNA-ROR, miR-145 and the clinicopathologic features of colon cancer was performed. CD44(-)CD133(-) and CD44(+) CD133(+) cells were isolated from SW1116 by using flow cytometry. The expression of CD44, CD133, Oct4, Sox2, Nanog, lincRNA-ROR and miR-145 in cells were detected by qPCR. The relationship between lincRNA-ROR, miR-145, Oct4, Sox2 and Nanog was analyzed by bioinformatics, dual luciferase reporter assay, qPCR and Western blot. The effects of silencing lincRNA-ROR on the proliferation and chemosensitivity of colon cancer stem cells were detected by MTT, colony formation. Results: LincRNA-ROR was frequently up-regulated and inversely correlated with miR-145 down-regulation in the colon cancer specimens(P<0.05). LincRNA-ROR was related to tumor size, lymph node involvement and distant metastasis(P<0.05), and miR-145 was found related to tumor size and tumor location(P<0.05). CD44(+) CD133(+) cells were successfully isolated from SW1116 by flow cytometry. The levels of CD44, CD133, Oct4, Sox2, Nanog, lincRNA-ROR in CD44(+) CD133(+) cells were significantly increased, while miR-145 was decreased compared with CD44(-)CD133(-)cells(P<0.05). The levels of CD44, CD133, lnc-ROR in CD44(+) CD133(+) cells were significantly reduced upon cell adherence, while miR-145 was significantly increased(P<0.05). Bioinformatics analysis revealed that lincRNA-ROR shared miRNA response elements with core transcription factors Oct4, Sox2 and Nanog. MiR-145 significantly inhibited the expression of lincRNA-ROR, Oct4, Sox2 and Nanog. Silencing lincRNA-ROR significantly inhibited colon cancer stem cells proliferation and increased the sensitivity to chemotherapy. Conclusions: Linc-ROR functions as a key ceRNA to prevent core TFs, e. g., Oct4, Sox2, Nanog, from miR-145-mediated suppression in colon cancer stem cells and regulates cell proliferation and chemosensitivity.The data may provide insights into the pathophysiological interactions of the components of genetic networks in the development of colon cancer and may lead to new therapies in the future.

Three-dimensional assessment of root migration and rotation patterns after coronectomy: bone-embedded roots versus soft tissue-covered roots.

In this study, a three-dimensional evaluation was performed to explore differences between bone-embedded and soft tissue-covered roots after mandibular third molar (M3M) coronectomy. Patients were recruited according to the results of cone-beam computed tomography, 6 months after coronectomy. Completely bone-embedded M3Ms were assigned to group B, while completely soft tissue-covered M3Ms were assigned to group S. Data were recorded using digital software. A total of 213 M3Ms in 181 patients were investigated, of which 170 were assigned to the two study groups. Age was the primary factor influencing root migration (P<0.001). The smaller the degree of angulation of the M3M, the more likely was the root complex to rotate distally (r=-0.37, P<0.001). The depth of the impacted M3M contributed to the regeneration of new bone (P≤0.008). The length of the root complex (odds ratio 0.82, P=0.048) and distance from the root to the alveolar crest (odds ratio 1.23, P=0.026) were two critical factors influencing whether the root complex was bone-embedded. Ensuring that the length of the root complex is <7.6mm and the distance between the root and alveolar crest is ≥5mm were both found to be critical to the remaining root being completely bone-embedded and thus preventing eruption and the need for secondary surgery.

Inhibition of miR-133b indicates poor prognosis and promotes progression of OSCC via SOX4.

OBJECTIVE: Oral squamous cell carcinoma (OSCC) accounts for the first largest proportion of oral and maxillofacial malignancies worldwide. Increasing studies have indicated that miRNAs are involved in the regulation of various tumors, including OSCC. However, the exact role of miR-133b in OSCC has not been fully elucidated. Here, we aimed to explore the effects of miR-133b on the development and progression of OSCC and its related mechanisms. PATIENTS AND METHODS: Expression of miR-133b in 44 paired OSCC tissues and adjacent normal tissues were detected using quantitative real-time polymerase chain reaction (qRT-PCR). Clinicopathological characteristics were collected from OSCC patients, and the relationship between miR-133b expression and the prognosis of patients was analyzed. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) and colony formation assays were employed to measure the proliferation of OSCC cells transfected with miR-133b inhibitors or mimics. Cell invasion and migration were detected using transwell and Matrigel experiments, respectively. Bioinformatics and Western blot were applied to investigate the possible underlying mechanism of miR-133b in OSCC. RESULTS: MiR-133b was lowly expressed in OSCC tissues compared to adjacent normal tissues (p<0.05). Lower expression miR-133b indicated a significantly worse prognosis of OSCC patients (p<0.05). Over-expression of miR-133b reduced the growth and metastasis of SCC9 cells (p<0.05). Transfection of miR-133b inhibitors obviously enhanced the proliferation, migration and invasion of TSC-15 cells (p<0.05). SRY-Box Transcription Factor 4 (SOX4) was verified as a specific target for miR-133b. Up- or down-regulation of miR-133b decreased or increased the protein expression level of SOX4 in OSCC, respectively (p<0.05). CONCLUSIONS: MiR-133b was lowly expressed in OSCC tissues and cell lines. Down-regulation of miR-133b reduced the proliferation, invasion and migration of OSCC cells via regulating SOX4. All our findings suggested that miR-133b could be used as a potential target for the treatment of OSCC.

Study on genes with altered expression in alpha-amanitin poisoned mice and evaluation on antagonistic effects of traditional Chinese medicines against toxicity of alpha-amanitin.

The forward and reverse cDNA subtractive libraries before and after the toxic effect of alpha-amanitin were constructed by suppression subtractive hybridization and randomly selected clones from each subtractive library were screened by PCR and dot blot hybridization. A total of 85 genes with altered expression were finally identified, with 41 genes from the forward library and 44 from the reverse library. Subsequently, the antagonistic effects of candidate traditional Chinese medicines were evaluated based on the genetic transcription levels of the genes with significant altered expression, including Catnbeta, Flt3-L, IL-7r and Rpo2-4. The results indicated that Silybum marianum (L.) Gaert and Ganoderma lucidum had significant down-regulated effects on the transcription level of Catnbeta that was up-regulated by alpha-amanitin, and the two herbs also up-regulated the transcription levels of Flt3-L and Rpo2-4. Silybum marianum (L.) had significant up-regulated effects on the IL-7r that was down-regulated by alpha-amanitin. These preliminary studies suggested that Silybum marianum (L.) and Ganoderma lucidum were effective antagonists against the toxicity of alpha-amanitin.

[Experimental study on the effects of tumor necrosis factor-α monoclonal antibody on autophagy level in allergic rhinitis mice].

Objective: To observe the effect of tumor necrosis factor-α (TNF-α) monoclonal antibody on autophagy in allergic rhinitis (AR) mice. Methods: Thirty six weeks old BALB/c mice were randomly divided by random number table method into five groups: control group, model group (AR group), TNF-α antibody intervention group (AR+TNF-α group), autophagy inhibitor (3-methylindole, 3-NA) intervention group (AR+3-MA group), TNF-α antibody combined with autophagy inducer rapamycin (RAP) intervention group (AR+TNF-α+RAP group), with 6 mice in each group. AR model was established by conventional method, the corresponding reagent was administered before nasal cavity stimulation sensitization and during the whole experiment. Behavioral scores of mice were obtained, blood was collected from the eye socket, and mice in each group were sacrificed to collect nasal mucosa tissue samples. Pathological changes of nasal mucosa were observed by hematoxylin-eosin staining. Expression levels of inflammatory factor and IgE in serum were detected by enzyme-linked immunosorbent assay (ELISA). Expressions of autophagy related indicators microtubule-associated protein-1 light chain-3B (LC3B), Beclin-1, sequestosome1 (p62), autophagy-related 5 (ATG5), autophagy-related 7 (ATG7) were measured by Real-time PCR and Western blot. The aggregation of LC3B protein was observed by immunofluorescence. SPSS 19.0 software was used for statistical analysis. Results: Compared with the AR model group, symptoms of AR in AR+TNF-α group and AR+3-MA group were mild; the pathological changes of nasal mucosa were weak; the expression of IgE, TNF-α, interleukin 4 (IL-4), interferon-γ (IFN-γ) in serum significantly reduced (IgE: 666.19±78.35 (x±s) vs. 692.38±64.29 vs. 1 059.05±146.44, TNF-α: 112.06±12.95 vs. 113.17±15.43 vs. 161.22±17.96, IL-4: 54.05±7.14 vs. 58.26±5.67 vs. 79.95±6.33, IFN-γ: 28.58±4.51 vs. 30.67±2.60 vs. 39.83±3.31, all P<0.05), and the expression of LC3B Ⅱ/Ⅰ, Beclin-1, ATG5, ATG7 in nasal mucosa significantly decreased, the expression of p62 significantly elevated. After intervention with autophagy inducer RAP, the therapeutic effect of TNF-α monoclonal antibodies on AR was antagonized. Conclusion: TNF-α monoclonal antibody significantly improves nasal symptoms in AR mice by inhibiting autophagy levels.

Development of neurotrophic molecules for treatment of neurodegeneration.

Over the past several years, neurotrophic factors have made considerable progress from the laboratory into the clinic. Evidence from preclinical and clinical studies indicates that it may be possible to use neurotrophic factors to prevent, slow the progression of, or even reverse the effects of a number of neurodegenerative diseases and other types of insults in both the central and peripheral nervous system. Their potential importance in the development of therapeutic agents against neurodegenerative disorders and nerve injury has led to a flurry of activity towards understanding their structure, function and signalling mechanisms. Approaches to develop pharmacological agents that target neurotrophic factors, their receptors or neurotrophic factors signalling pathways have been attempted. This review focuses on some of the major themes and lines of mechanistic and therapeutic advances in this fast-moving field of neuroscience.

Scavengase p20: a novel family of bacterial antioxidant enzymes.

A novel antioxidant enzyme designated scavengase p20 was identified in various pathogenic bacteria through database searching for sequences strikingly homologous to a recently discovered Escherichia coli thiol peroxidase p20. The direct biochemical evidence for the existence of scavengase p20 in Haemophilus influenzae, Streptococcus pneumoniae and Helicobacter pylori was provided by protein microsequencing and by in vitro assays for antioxidant activities. Overlapping genes encoding scavengase p20 and superoxide dismutase were recognized in H. pylori and their functional implications are discussed.

Renal ultrasound using parametric imaging techniques to detect changes in microstructure and function.

RATIONALE AND OBJECTIVES: Signal processing techniques have been used to generate parametric ultrasound images that describe properties of tissue microstructure. METHODS: Images of the average scatterer size (D) and integrated backscatter coefficient (IBC) for normal dog kidneys were examined. RESULTS: With parametric ultrasound the authors identified sources of cortical backscatter and observed microanatomical changes corresponding to ischemia. In particular, scatterer size images acquired in vitro and in vivo show it is possible to rapidly assess changes and differences in the average glomerular diameter and the average arteriolar cross-sectional diameter. CONCLUSIONS: A more direct interpretation of sonographic image data is possible with this new type of imaging. Parametric imaging may have a diagnostic role as a means to differentiate among conditions producing increased cortical echogenicity and to detect important structural indicators such as glomerular hypertrophy.

Regional gastric mucosal blood flow after parietal cell vagotomy in dogs.

In this study we used the recently validated H2 clearance method to perform endoscopic measurements of gastric mucosal blood flow (MBF) in anesthetized dogs before and after parietal cell vagotomy (PCV). Under resting conditions, MBF in the gastric corpus before PCV was 72 +/- 5 ml/min/100 gm. This was not altered significantly at 4, 8, or 16 weeks after PCV, and there were not significant long-term changes in MBF on the greater or lesser curvatures of the corpus individually. Before PCV infusion of pentagastrin (8 micrograms/kg/hr) elicited increases in corpus MBF to 104 +/- 4 ml/min/100 gm, accompanied by increases in gastric acid output from resting levels of 2.1 +/- 0.9 to 38.6 +/- 2.4 mEq/hr (p less than 0.001). PCV significantly reduced pentagastrin-stimulated acid secretion by 50%, and secretory inhibition was accompanied by significant reductions in pentagastrin-stimulated MBF in the corpus. Pentagastrin did not alter antral MBFs before or after PCV. In summary PCV does not elicit significant long-term changes in resting MBF in different regions of the gastric corpus, and PCV significantly diminishes increases in acid output and corpus MBF that are normally stimulated by pentagastrin. These observations suggest that alterations in gastric MBF after PCV may be attributable to alterations in acid secretion.

Comparison of gastric mucosal blood flow as measured by H2 gas clearance and microspheres during secretory stimulation and inhibition.

H2 clearance is a recently described method of measuring gastric mucosal blood flow that has great potential for clinical use. However, the effects of luminal pH and of secretory activity of the gastric mucosa on the accuracy of H2 clearance measurements have not been systematically examined. We therefore tested the validity of H2 clearance measurements at different pHs in both in vitro and in vivo systems. In addition, we compared measurements by H2 clearance and radioactive microspheres during stimulation and suppression of acid secretion. In vitro, H2 washout was relatively constant over a range of pHs from 2.0 to 8.0. In chambered segments of canine fundus in vivo, H2 clearance was not significantly affected by pH of the luminal solutions either in the resting state or at lower blood flows induced during infusion of vasopressin. Finally, there was a close correlation (r = 0.85; p less than 0.001) between H2 clearance and microsphere measurements under resting conditions, during intravenous histamine stimulation, and after infusion of cimetidine to suppress acid secretion. In summary, H2 clearance reliably and accurately measures gastric mucosal blood flow at different luminal pHs and under conditions that stimulate or suppress acid secretion.

Platelet activating factor-induced changes in gastric motility and vascular resistance.

Our study evaluated the hypothesis that gastric contractions may contribute to ischemia by increasing vascular resistance. Using an ex vivo segment of the dog's stomach as the experimental model, contractions were induced with platelet activating factor (PAF) and bethanechol, a cholinergic vasodilator. Spontaneous contractions produced slight increases in luminal pressure and corresponding increases in vascular resistance. PAF caused statistically significant, dose-dependent increases in the force of gastric contractions that were highly correlated with phasic changes in vascular resistance. To ensure that the relationship between contractions and vascular resistance was independent of vascular tone, we next examined responses to bethanechol. Bethanechol stimulated contractions that also transiently increased both luminal pressure and vascular resistance. Our results demonstrate that gastric contractions markedly increase vascular resistance and support the hypothesis that hypercontractility may contribute to the development of mucosal ischemia during ulceration.

Magnetic resonance imaging (MRI) of a cookie in comparison with time-lapse photographic analysis (TLPA) during baking process.

Magnetic Resonance Imaging (MRI) has been used to study the baking of a cookie. The structural and dynamic changes occurring during baking have been monitored, including changes in the internal moisture saturations and distribution. The images reveal the moisture distribution is initially uniform, and during baking a gradient in moisture develops from the interior to the edge. Changes in physical dimensions calculated from the data are consistent with those obtained from time-lapsed photography.