Consensus recommendations for the screening, diagnosis, and management of Helicobacter pylori infection in Hong Kong

Helicobacter pylori infection causes chronic gastric inflammation that contributes to various gastroduodenal diseases, including peptic ulcer and gastric cancer. Despite broad regional variations, the prevalence of resistance to antibiotics used to manage H pylori infection is increasing worldwide; this trend could hinder the success of eradication therapy. To increase awareness of H pylori and improve the diagnosis and treatment of its infection in Hong Kong, our consensus panel proposed a set of guidance statements for disease management. We conducted a comprehensive review of literature published during 2011 and 2021, with a focus on articles from Hong Kong or other regions of China. We evaluated the evidence using the Oxford Centre for Evidence-Based Medicine's 2011 Levels of Evidence and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system and sought consensus through online voting and a subsequent face-to-face meeting, which enabled us to develop and refine the guidance statements. This report consists of 24 statements regarding the epidemiology and burden, screening and diagnosis, and treatment of H pylori. Key guidance statements include a recommendation to use the test-and-treat approach for high-risk individuals, as well as the confirmation that triple therapy with a proton pump inhibitor, amoxicillin, and clarithromycin remains a valid first-line option for adults and children in Hong Kong.

High-dose proton pump inhibitors are associated with hospitalisation in bronchiectasis exacerbation

BACKGROUND Bronchiectasis is a common respiratory disease complicated by periodic exacerbations. The association with different degrees of gastric acid suppression has not been well studied.METHODS A retrospective cohort study of 350 patients was conducted to investigate the association of different gastric acid suppressants with bronchiectasis exacerbation that required hospitalisation. Components of FACED (FEV₁% predicted, age, chronic colonisation by Pseudomonas aeruginosa, radiological extent of the disease, and dyspnoea) were adjusted in multivariate analysis.RESULTS Among patients with exacerbation of bronchiectasis, 52 (14.9%) required hospitalisation. Prescription of a high-dose of proton pump inhibitors (PPI) was associated with increased risk of bronchiectasis exacerbation requiring hospitalisation (adjusted OR 2.77, 95% CI 1.01-7.59; P = 0.05). There was no significant association with use of a histamine-2 receptor antagonist (H2RA) (OR 1.28, 95% CI 0.32-5.06) or low-dose PPI (OR 1.47, 95% CI 0.42-5.13). Nonetheless, patients prescribed a high dose of PPI required a significantly longer hospital stay for exacerbation (13.1 ± 1.4 days) than patients not prescribed a gastric acid suppressant (8.2 ± 2.6 days) or those on a low dose PPI (8.3 ± 1.3 days) and H2RA (6.50 ± 1.50 days).CONCLUSIONS Risk of bronchiectasis exacerbation requiring hospitalisation was increased among high-dose PPI users, but not those prescribed an H2RA or low-dose PPI.

Prehospital electrocardiogram shortens ischaemic time in patients with ST-segment elevation myocardial infarction

INTRODUCTION

Total ischaemic time should be shortened as much as possible in patients with ST-segment elevation myocardial infarction (STEMI). This study evaluated whether prehospital 12-lead electrocardiogram (ECG) could shorten system delay in STEMI management.

METHODS

From November 2015 to November 2017, 15 ambulances equipped with X Series Monitor/ Defibrillator (Zoll Medical Corporation) were used in the catchment area of Queen Mary Hospital, Hong Kong. Prehospital ECG was performed for patients with chest pain; the data were tele-transmitted to attending emergency physicians at the Accident and Emergency Department (AED) for rapid assessment. Data from patients with STEMI who were transported by these 15 ambulances were compared with data from patients with STEMI who were transported by ambulances without prehospital ECG or who used self-arranged transport.

RESULTS

Data were analysed from 197 patients with STEMI. The median patient delay for activation of the emergency response system was 90 minutes; 12% of patients experienced a delay of >12 hours. There was a significant difference in delay between patients transported by ambulance and those who used self-arranged transport (P<0.001). For system delay, the use of prehospital ECG shortened the median time from ambulance on scene to first ECG (P<0.001). When performed upon ambulance on scene, prehospital ECG was available 5 minutes earlier than if performed in ambulance compartment before departure. Use of prehospital ECG significantly shortened AED door-to-triage time, AED door-to-first AED ECG time, AED door-to-physician consultation time, and length of stay in the AED (P<0.001 for all comparisons).

CONCLUSION

Prehospital ECG shortened ischaemic time prior to hospital admission.

Prehospital 12-lead electrocardiogram for patients with chest pain: a pilot study

INTRODUCTION

After ST-segment elevation myocardial infarction (STEMI), it is vital to shorten reperfusion time. This study examined data from a pilot project to shorten the door-to-balloon (D2B) time by using prehospital 12-lead electrocardiogram (ECG).

METHODS

Fifteen ambulances equipped with X Series^® Monitor/Defibrillator (Zoll Medical Corporation) were deployed to the catchment area of Queen Mary Hospital, Hong Kong, from November 2015 to December 2016. For patients with chest pain, prehospital 12-lead ECG was performed and tele-transmitted to attending physicians at the accident and emergency department for immediate interpretation. The on-call cardiologist was called before patient arrival if STEMI was suspected. Data from this group of patients with STEMI were compared with data from patients with STEMI who were transported by ambulances without prehospital ECG or by self-arranged transport.

RESULTS

From 841 patients with chest pain, 731 gave verbal consent and prehospital ECG was performed and transmitted. Of these, 25 patients with clinically diagnosed STEMI required emergency coronary angiogram with or without primary percutaneous coronary intervention. The mean D2B time for these 25 patients (93 minutes) was significantly shorter (P=0.003) than that for 58 patients with STEMI transported by ambulances without prehospital ECG (112 minutes) and that for 41 patients with STEMI with self-arranged transport (138 minutes). However, shorter reperfusion time was only recorded during daytime hours (08:00-17:59). No statistically significant difference in 30-day mortality was found.

CONCLUSION

Prehospital ECG is technologically feasible in Hong Kong and shortens the D2B time. However, shorter reperfusion time was only recorded during daytime hours.

Successful resuscitation after out-of-hospital cardiac arrest

A 66-year-old woman presented to the emergency department after a witnessed cardiac arrest, having had compression-only cardiopulmonary resuscitation initiated by her son on the backseat of his car. She was resuscitated in the emergency department for 1 hour before the return of spontaneous circulation. She then underwent primary percutaneous coronary intervention and therapeutic hypothermia. She was discharged without significant neurological deficit. This case illustrates better survival and neurological outcome can be achieved by prompt implementation of a 'chain of survival' interventions and therapeutic hypothermia.

An innovative web-based peer support system for medical students in Hong Kong

BACKGROUND

Psychological morbidity is commonly found in medical students.

AIMS

The Mental Health Support Group (MSG), a student-initiated and student-run web-based peer support service aims to provide mental health information, e mail counseling and an online forum for medical students.

METHODS

The development process of MSG is described in the paper with presentation of preliminary evaluation results.

RESULTS

Preliminary evaluation shows promising results. Student members of MSG acquired valuable skills in counseling, communication, webpage design and maintenance of an online forum.

CONCLUSIONS

Future challenges include succession issues, strategies to keep up the momentum, enhancement of publicity and further diversification of service to meet the needs of our students.

Influence of epinephrine as an adjuvant to epidural morphine for postoperative analgesia

The influence of the addition of epinephrine to epidural morphine on postoperative analgesia were investigated in 60 ASA physical status I or II patients aged average 45 yr. The treatments were given following lower extremity operation under epidural anesthesia with 2% Xylocaine solution in 20 mL. The subjects were randomly divided into 2 groups. Group A (n = 30) received 2 mg epidural morphine in 10 mL normal saline without epinephrine. Group B (n = 30) received 2 mg epidural morphine in 10 mL normal saline with epinephrine 0.1 mg (1:100,000, 10 micrograms/mL). Patients were assessed for quality and duration of postoperative analgesia, as well as the incidence and severity of side effects after epidural morphine administration. The addition of epinephrine to epidural morphine had significantly increased the quality and duration of analgesia. The side effects of pruritus, nausea, vomiting, and urinary retention were more intense after epinephrine-morphine administration. However, respiratory depression was not observed in both groups.

Some solvents for antiepileptics have proepileptic potencies in the WAG/Rij rat model for absence epilepsy

Some solvents for antiepileptics were tested, for 4 consecutive days, in a rat model (the WAG/Rij inbred strain) for absence epilepsy. Electroencephalogram registrations and behavioral observations suggested that both Tween-80 and a mixture of saline/ethanol/propylene glycol caused an increase in the number of epileptic phenomena. This increase was not significant and restricted to injection day 1 with Tween-80 but was significantly present during all 4 injection days with the saline/ethanol/propylene glycol mixture. Furthermore, with this latter solvent the increase became larger during consecutive days. Because of the proepileptic potencies and the differential time effects of these solvents, their usage should be seriously questioned.

A comparative evaluation of the individual anaerobic threshold and the critical power

The individual anaerobic threshold (IAT) is defined as the highest metabolic rate where blood lactate (La) concentrations are maintained at a steady-state during prolonged exercise. The asymptote of the hyperbolic relationship between power output and time to fatigue has been defined as the critical power (CP), which, in theory, represents the highest metabolic rate where a steady-state response can be achieved during prolonged exercise. Since IAT and CP may define the same power output, the purpose of this study was to compare the gas exchange, blood La, and acid-base responses during exercise at the metabolic rates defined as IAT and CP. Fourteen males performed a maximal incremental cycle exercise test that was followed by a light active recovery period to determine IAT. Subsequently, subjects exercised to fatigue at five power outputs (calculated to elicit from 90% to 110% VO2max) to determine CP. IAT occurred at a significantly lower power output and VO2 (235 +/- 44 W and 2.97 +/- 0.47 l.min-1, respectively) compared with CP (265 +/- 39 W and 3.35 +/- 0.41 l.min-1, respectively). During 30 min of exercise at IAT, blood La levels increased during the initial 10 min to 3.9 +/- 1.9 mmol.l-1 but did not change during the final 15 min. Blood pH decreased to 7.32 +/- 0.04 at 5 min and did not change thereafter, while PCO2 fell from 41.5 +/- 3.2 mm Hg at 5 min to 36.2 +/- 3.6 mm Hg at 30 min. Only one subject completed 30 min of exercise at CP.(ABSTRACT TRUNCATED AT 250 WORDS)

Incremental test protocol, recovery mode and the individual anaerobic threshold

The individual anaerobic threshold (IAT) is defined as the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady-state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of IAT following both a submaximal or maximal incremental exercise test. Seven males (VO2max = 57.6 +/- 5.8 ml.kg-1.min -1) did two submaximal, incremental cycle exercise tests (30 W and 4 min per step) and two maximal incremental tests. Blood was sampled repeatedly during exercise and for 12 min during the subsequent recovery period, which was passive for one submaximal and one maximal test and active (approximately 35% VO2max) during the other tests. An IAT metabolic rate and power output were calculated for the submax-passive (IATsp, LA = 1.85 +/- 0.42 mmol.l-1), max-passive (IATmp, LA = 3.41 +/- 1.14 mmol.l-1), submax-active (IATsa, LA = 2.13 +/- 0.45 mmol.l-1) and max-active (IATma, LA = 3.44 +/- 0.73 mmol.l-1) protocols. At weekly intervals, the subjects exercised for 30 min at one of the four IAT metabolic rates. Active recovery did not affect the calculation of IAT, but following the maximal incremental tests, IAT occurred at a higher (p less than 0.05) power output, absolute VO2 and %VO2max (71% VO2max) compared with the IAT determined with the submaximal incremental tests (61% VO2max).(ABSTRACT TRUNCATED AT 250 WORDS)

A novel mechanism of mycophenolic acid resistance in the protozoan parasite Tritrichomonas foetus

Tritrichomonas foetus relies primarily on the salvage of hypoxanthine to supply purine nucleotides. Mycophenolic acid disrupts T. foetus growth by specifically inhibiting inosine-5'-monophosphate (IMP) dehydrogenase, thereby blocking the biosynthesis of guanine nucleotides from hypoxanthine. We have cloned a T. foetus strain (mpar) that was 50-fold more resistant to mycophenolic acid than wild type (IC50 = 1 mM for mpar vs 20 microM for wild type). None of the usual mechanisms of drug resistance could be identified. IMP dehydrogenase isolated from T. foetus mpar was indistinguishable from the wild type enzyme. No difference in mycophenolic acid uptake or metabolism was detected between the wild type and mpar strains. Mycophenolic acid (100 microM) completely blocked the conversion of adenine and hypoxanthine to guanine nucleotides in T. foetus mpar, although no inhibition of T. foetus mpar growth was observed at this concentration. These observations indicate that the major purine salvage pathways must be altered in T. foetus mpar so that guanine nucleotide biosynthesis no longer requires IMP dehydrogenase. T. foetus mpar incorporated xanthine more efficiently into the nucleotide pool relative to hypoxanthine and guanine than wild type. Xanthine incorporation via XMP provided an IMP dehydrogenase independent route to guanine nucleotides that would enable the parasite to become mycophenolic acid resistant. No difference could be detected between wild type and mpar hypoxanthine-guanine-xanthine phosphoribosyltransferases, the key enzyme in purine base incorporation into nucleotides. Two alterations were identified in the purine salvage network of mpar: it was deficient in hypoxanthine transport and had diminished adenine deaminase activity. The apparent net result of these two changes was to lower the intracellular concentration of hypoxanthine in mpar. Hypoxanthine and adenine inhibited the incorporation of xanthine into the nucleotide pool in wild type T. foetus, but not in mpar. The mpar strain, therefore, can salvage xanthine more efficiently from a mixture of purines and thus bypass the drug block at IMP dehydrogenase.

Isolation and characterization of a collagen fibril-associated dermatan sulphate proteoglycan from bovine lung

Dermatan sulphate proteoglycans have been extracted from bovine lung with 2.0 M CaCl2 and isolated using CsCl density gradient centrifugation, DEAE ion-exchange chromatography, gel chromatography and preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Ultrastructurally these proteoglycans are specifically associated with collagen fibrils. Dermatan sulphate (Mr 15.10(3)-35.10(3), with a strong prevalence for the higher Mr) is link via an O-glycosidic bond to a protein core, which is rich in Asx, Glx and Leu. Of the total uronic acid, 91% is iduronic acid. A part of the glucuronic acid residues is located near the protein core and a large cluster of disaccharides is devoid of glucuronic acid residues. An inhibition enzyme immunoassay has been developed to quantitate the proteoglycan. A model for the interaction between dermatan sulphate proteoglycans and collagen fibrils is proposed.

Chloroalanyl antibiotic peptides: antagonism of their antimicrobial effects by L-alanine and L-alanyl peptides in gram-negative bacteria

A large number of structurally diverse di- and tripeptides containing the alanine racemase inactivator beta-chloro-L-alanine (beta-Cl-LAla) have been synthesized, and their antibacterial properties in vitro have been evaluated. The dipeptides 1, 3-6, and 8-17 and the tripeptide 20 are all broad-spectrum antibacterial agents with considerable potency against both Gram-positive and Gram-negative species, but none of these peptides improves dramatically on the antibiotic efficacy of the previously described beta-Cl-LAla-beta-Cl-LAla, 9 (Cheung, K. S.; Wasserman, S. A.; Dudek, E.; Lerner, S. A.; Johnston, M. J. Med. Chem. 1983, 26, 1733). Gram-negative microorganisms, such as Escherichia coli, Hemophilus influenzae, Shigella flexneri, and Enterobacter species are consistently resistant to any haloalanyl peptide containing an alanyl residue, such as the dipeptide LAla-beta-Cl-LAla (2) and the tripeptides LMet-LAla-beta-Cl-LAla (7), LAla-LAla-beta-Cl-LAla (18), and LVal-LAla-beta-Cl-LAla (19). Correspondingly, these same organisms are protected from the bactericidal effects of 9 by supplementation of the growth medium with LAla or LAla-LAla. Escherichia coli JSR-O exposed to 9, but protected from lysis by sucrose stabilization, has only about 10% the normal level of intracellular alanine racemase activity. But when these cells are cultured in the presence of 9 with LAla supplementation, or in the presence of 2 with no supplementation, the alanine racemase levels are only about 20-30% below control values. These findings suggest that the resistance of Gram-negative species to chloroalanyl peptides containing alanyl units arises from the ability of LAla to protect the targeted racemase from inactivation by beta-Cl-LAla in vivo, an event which otherwise leads to cell death and lysis. Inactivation of alanine racemase in Gram-positive organisms appears not to be the cellular event that confers sensitivity of these species to a haloalanyl peptide.

Mechanisms of action of chloroalanyl antibacterial peptides. Identification of the intracellular enzymes inactivated on treatment of Escherichia coli JSR-O with the dipeptide beta Cl-LAla-beta Cl-LAla

The dipeptide beta Cl-LAla-beta Cl-LAla is an antibacterial agent designed to utilize bacterial peptide transport for intracellular delivery of the alanine racemase inactivator beta Cl-LAla. The minimum inhibitory concentrations (MICs) for the peptide against Gram-negative species grown on enriched agar medium range from 1.56 to 12.5 micrograms/ml; MICs are increased to greater than 100 micrograms/ml when D-alanine is included in the medium, indicating that alanine racemase is, in fact, inhibited in sensitive species. When susceptible Gram-negative cells are grown on a minimal medium, D-alanine supplementation alone does not increase the MICs for beta Cl-LAla-beta Cl-LAla, but complete protection is afforded by supplementation with D-alanine, L-valine, L-leucine, and L-isoleucine. In liquid culture, the peptide is: bactericidal and lytic against Escherichia coli JSR-O growing in enriched medium or in minimal medium supplemented with the branched-chain amino acids; only inhibitory against these cells growing in minimal medium supplemented with D-alanine; and ineffective against these cells in minimal medium containing the branched-chain amino acids plus D-alanine. Cells exposed to beta Cl-LAla-beta Cl-LAla (with the protection of the four amino acids) have specific activities of both alanine racemase and transaminase B that are lower than those of cultures not treated with the peptide. Finally, E. coli JSR-O alanine racemase experiences time-dependent loss of activity when exposed to the dipeptide in the presence of aminopeptidases; the dipeptide alone is not an inactivator of the racemase in vitro. These results suggest the following mechanism of action for beta Cl-LAla-beta Cl-LAla: transport of the dipeptide into the cell; intracellular hydrolysis to give accumulation of beta Cl-LAla; and subsequent inactivation of targeted enzymes. Whether inactivation of the racemase or of the transaminase determines the pathophysiologic effects of the peptide depends on the composition of the growth medium.

Enhanced replication of murine cytomegalovirus in murine leukemic lymphocytes

Replication in vitro of murine cytomegalovirus was found to be enhanced in lymphoid cells from leukemic (AKR/J) mice as compared with similar cells from nonleukemic animals. Prolonged productive murine cytomegalovirus infection in lymphoid organs in vivo was demonstrable only in leukemic AKR/J mice. Latent nonproductive murine cytomegalovirus infection established in young nonleukemic AKR/J mice was invariably reactivated and expressed in salivary glands and lymphoid organs after these animals became leukemic.

Chloralanyl and propargylglycyl dipeptides. Suicide substrate containing antibacterials

A set of dipeptides containing the amino acid residues beta-chloroalanine and propargylglycine, which are mechanism-based inactivators of purified microbial enzymes (alanine racemase and cystathionine gamma-synthase, respectively), have been synthesized, and their antibacterial properties in vitro have been evaluated. Dipeptides containing a single beta-chloro-L-alanyl residue (e.g., 3, 5, 9, and 10) or a single L-propargylglycyl residue (e.g., 12 and 15) are potent antibacterials. The in vitro antibiotic activity of beta-chloro-L-alanine and of L-propargylglycine is increased as much as 4000-fold by incorporation of these residues into a dipeptide. Compounds that contain only a single enzyme-inactivating amino acid together with a second L-alanyl residue (3, 5, 12, and 15) have a restricted range of activity: of the species tested, only Streptococcus agalactiae, Staphylococcus aureus, and Staphylococcus epidermidis are sensitive. However, peptides that contain two suicide-substrate residues [e.g., beta-Cl-LAla-beta-Cl-LAla (8) or LppGly-LppGly (18)] are broad-spectrum antibacterials; as many as 12 different species of the 16 surveyed are sensitive. Dipeptides that contain an amino-terminal L-methionyl (9) or an L-norvalyl (10) residue and a carboxy-terminal beta-chloro-L-alanyl unit are also effective against a large number of organisms; the spectra of activity are like those seen for 8 and 18. A "mixed" dipeptide [beta-Cl-LAla-LppGly, (21)] gives apparent synergism of antibiotic action of beta-chloro-L-alanine and of L-propargylglycine when these two residues are incorporated into a single structure. Peptides of the D,D configuration (4, 6, 13, 16, and 20) and ones of L,D stereochemistry (e.g., 7) are not antibacterials. Peptides containing one (11 and 14) and two (17) D,L-propargylglycyl residues are unresolved sets of diastereomers; the mixtures of compounds are between two- and fourfold less active than the correspondingly resolved L,L dipeptides (12, 15, and 18). These findings are consistent with a mechanism of action for these antibiotics involving stereoselective processing of the peptidyl unit in vivo.

Effectiveness of acycloguanosine and trifluorothymidine as inhibitors of cytomegalovirus infection in vitro

The effectiveness of acycloguanosine (acyclovir) and trifluorothymidine (TFT) as inhibitors of cytomegalovirus (CMV) infection was tested using a plaque-reduction assay. Two laboratory strains and seven clinical isolates were employed. The results indicated that both acyclovir and TFT were ineffective in inhibiting viral cytopathic effect (CPE) below the concentration of 50 microM. At concentrations of 100 microM or more, greater than a 50 percent inhibition was achieved by both acyclovir and TFT on all clinical isolates. Although complete inhibition of plaque formation was seldom achieved even at a drug concentration as high as 200 microM, a reduction of plaque size was consistently observed at drug concentrations above 100 microM. When a low dose of virus was used for infection, ED50 could be achieved at an acyclovir concentration of 50 microM. Laboratory strains of CMV were found to be more resistant than the clinical isolates to inhibition of acyclovir.

An evaluation under code of new techniques for the detection of cytomegalovirus antibodies: sensitivity of assays and importance of immune complexes

Given the morbidity and occasional mortality associated with cytomegalovirus infection and the requirement for good seroepidemiologic tools, assays of high sensitivity and reliability are needed for detection of cytomegalovirus-specific antibody. We report the successful application of two sensitive techniques, antibody-dependent cellular cytotoxicity (ADCC) and the enzyme-linked immunosorbent assay (ELISA) for the measurement of these antibodies and document their favorable comparison with conventional techniques, complement fixation (CF) and indirect hemagglutination (IHA). A coded panel of 48 sera from patients with culture-proven cytomegalovirus infection and disease controls was tested in a controlled fashion by all four procedures. Among 18 CF-positive sera, specific antibody was detected by IHA, ADCC and ELISA in dilutions 100 to 1000-fold higher than measurable by the CF test. Ten of 15 sera, seronegative by CF, were nevertheless found to be cytomegalovirus antibody-positive when assessed by the other procedures. Further, the importance of circulating antigen-antibody complexes upon ADCC test results was documented. Eight sera, known to be antibody-positive by other techniques but with an unexpectedly low (or negligible) capacity to induced ADCC, were found to be immune complex-positive by the Raji cell assay. Ultracentrifugation, useful in precipitating antigen-antibody complexes, enhanced ADCC activity in five of six sera known to be complex-positive. It is suggested that the simultaneous application of multiple antibody detection systems, particularly the newly-developed ones (ADCC, ELISA) will provide both earlier diagnostic information as well as a more comprehensive understanding of the human host's immune response to infection with cytomegalovirus.

A microtiter assay for cell-mediated cytotoxicity to cytomegalovirus antigens

The cell-mediated immune response is important to host defense against viruses, yet techniques with which to measure the contribution of lymphocytes (particularly K cells) to anti-viral cytotoxic reactions are not well-established. We describe a new procedure for measuring lymphocyte-mediated antibody-dependent immunity to cytomegalovirus. Central to the assay is the use of 51Cr-containing red blood cells labeled with purified viral antigen, which can be easily quantitated and readily stored for at least 72 hours. High sensitivity was observed, as sera with a 1: 512 complement fixation titer could be diluted 10,000-fold without extinguishing the detectable cytotoxic response. A set of conditions (target/effector ratio; dilution of serum; source and age of target cells; and incubation medium and time) was defined that optimized sensitivity, maintained a low level of background release, yet utilized small amounts of reagents. A kinetics study revealed that 80% of specific release of radioisotope occurred in the first 4 hours. Investigation of the epidemiology, diagnosis, and management of disease caused by CMV may be greatly aided by this new method for quantitating specific cell-mediated anti-viral immune reactivity.

Murine cytomegalovirus infection: hematological, morphological, and functional study of lymphoid cells

Mice were studied for 3 to 4 months after murine cytomegalovirus (MCMV) infection. Serial hematological parameters were evaluated. It was found that MCMV infection of mice were accompanied by the appearance of many atypical lymphocytes similar to those seen in association with the hematological features of mononucleosis associated with human CMV infection. Certain functions of splenocytes were studied in infected and uninfected animals during the 4 months after MCMV infection. Three periods were identifiable by the functional response of splenocytes during the course of MCMV infection. The initial phase was characterized by an elevated response of splenocytes to a T cell mitogen and a B cell mitogen (phytohemagglutinin and lipopolysaccharide, respectively). The intermediate phase was marked by productive virus replication in the salivary gland, injury to lymphoid elements, a depressed response of splenocytes to mitogens (phytohemagglutinin and lipopolysaccharide), and decreased humoral splenocytes to phytohemagglutinin stimulation was again increased, and a nonproductive latent infection was established. Study by scanning electron microscopy of splenocytes during the course of infection revealed morphological changes which were correlated with functional alterations.

Cytomegalovirus: detection in human colonic and circulating mononuclear cells in association with gastrointestinal disease

The specificity and strength of the reported association between cytomegalovirus (CMV) and colonic adenocarcinoma were tested by analysis of a consecutive series of surgically resected colons for: CMV-DNA by a DNA-DNA reassociation kinetics (hybridization) procedure; latent virus by co-cultivation of fresh tissue with indicator fibroblasts; and CMV viral antigens by immunofluorescence. Ten of 13 cancer patients whose colonic tissue was able to be examined by all techniques showed evidence of active or prior CMV infection. Four cancer specimens were CMV-DNA (hybridization)- positive; an additional specimen from a cancerous colon was culture-positive. In six instances, CMV DNA was detected in mucosal cells adjacent to colon adenocarcinoma. In tissue from one of three patients with ulcera tive colitis and two of seven patients with other non-neoplastic colonic disease, CMV DNA was also detected. No fresh colonic tissues were demonstrated to have CMV surface or nuclear antigens when examined by immunofluorescence. Culture of peripheral lymphocytes was positive for CMV in three of 14 cancer patients. A CMV specific defect in humoral immunity could not be documented in that most cancer patients, as well as cancer-free patients, exhibited circulating specific antibody to CMV and had a normal capacity for CMV-specific antibody-dependent cellular cytotoxicity. We conclude that CMV, probably in a latent form, is readily detectable in colonic cells of man, including those derived from malignant, pre-malignant and non-malignant tissues. Neither preferential replication in damaged tissue nor carriage of CMV by peripheral lymphocytes homing to gut appear to explain the presence of CMV in colon cells.

Murine cytomegalovirus: detection of latent infection by nucleic acid hybridization technique

The technique of nucleic acid hybridization was used to detect the presence of murine cytomegalovirus (MCMV)-specific deoxyribonucleic acid (DNA) in cell cultures and salivary gland tissues. The presence of approximately 4.5 and 0.2 genome equivalents per cell of MCMV-specific DNA was identified in cultures of salivary (ISG2) and prostate gland (IP) cells, respectively. These cells, derived from animals with experimentally induced latent infections, were negative for virus-specific antigens by immunofluorescence and on electron microscopy revealed no visible evidence of the presence of herpesviruses. A cell line derived from the salivary gland of an uninoculated animal (NSG2) was also found to possess MCMV-specific DNA (0.2 genome equivalents per cell). For this reason, salivary gland tissues from uninoculated animals supplied as "specific pathogen-free" mice by three commercial sources were tested upon arrival for the presence of MCMC-specific DNA. MCMV-specific DNA was detectable in pooled salivary gland extracts from uninoculated animals derived from two commercial sources. All of these animals were seronegative and virus negative by conventional infectivity assays.

Effects of murine cytomegalovirus infection on the immune response to a tumor allograft

The purpose of this study was to compare the effects of murine cytomegalovirus infection introduced after an EL4 ascites tumor allograft with cytomegalovirus infection accompanying or preceding the allograft. Parameters that were measured included documentation to the host's immune system. Depressed immune response of splenocytes from mice infected at any time before assay was documented by decreased responsiveness to phytohemagglutinin, to lipopolysaccharide, and to an alloantigen in mixed lymphocyte culture. In contrast, animals infected after grafting had enhanced lymphocyte-mediated cytolysis (LMC), enhanced serum-mediated cytolysis (SMC), and larger spleens than did animals that were only grafted and animals that were infected before grafting. Neither a depressive nor an enhancing effect of virus administered after grafting was reflected in vivo in reduced or increased graft clearance. Nonspecific effects of virus increased LMC and SMC in vitro, but the primary effect of viral infection after grafting is immune depression.

Viral infection-homograft interactions in a murine model

The effects on some host defenses of murine cytomegalovirus (MCMV) and(or) EL(4), a mouse ascites homograft, were studied in mice. Assays of cellular and humoral immunity in response to either or both of these perturbations were carried out by quantitation of various immune activities.Limited studies demonstrated no effect of EL(4) inoculation on the host response to MCMV by organ viral titer, duration of viral persistence, or anti MCMV complement-fixing antibody titer. Prior infection with MCMV, however, resulted in greatly reduced numbers of splenocytes, the source in this study of immune effector cells. Residual splenocytes demonstrated less response to both phyto-hemagglutinin and lipopolysaccharide, particularly in the 2-3-wk interval after infection. Similarly, responder cells in mixed lymphocyte cultures were less reactive when derived from infected animals. Lymphocyte-mediated cytolysis of EL(4) was significantly less in mice infected on the day of and 7, 14, and 21 days before the tumor homograft with a return to control levels by 28 days. 90% of the cell-mediated cytolysis could be eliminated by treatment with anti-theta serum. Serum-mediated cytolysis of EL(4) was also reduced in infected animals. No suppressor cells or serum inhibitory factors could be identified in infected animals. Although alternative explanations exist, this study suggests that in infected animals there is a significant reduction in both the number and function of bone marrow-derived and thymus-derived cells directed against the alloantigens in EL(4).

Infection and fertilization of mice after artificial insemination with a mixture of sperm and murine cytomegalovirus

Female mice were artificially inseminated with a solution of sperm and cytomegalovirus (experimental) or sperm alone (control). Maternal infection was usually induced when virus accompanied sperm at insemination. Fertilization occurred in the presence of virus, and embryogenesis appeared normal on gross examination, although a slight reduction in the number of embryos was observed in the experimental group. Tissue cultures were prepared after gestation for 14 days from individual and pooled embryos. In one of 28 instances, virus was recovered from blind-passaged, experimental, embryonic fibroblasts. All control cultures were negative. This model may prove useful in further study of the pathogenesis of intrauterine cytomegalovirus infection.

Transmission and activation of cytomegalovirus with blood transfusion: a mouse model

A mouse model that mimics many features of human cytomegalovirus (CMV) infections associated with transfusion and perfusion is described. The concept of antigenic activation of CMV was tested by infusion of blood from latently infected mice, which were found to be virus-negative by tissue culture asssay, into uninfected allogeneic and isogenic hosts. After a latent period, virus was detectable invariably in allogeneic and only rarely in isogenic recipients. Transfusions from uninfected donors into latently infected mice activated CMV in heterologous and homologous recipients. These observations should assist in definition of relevant pathogenetic principles and may explain the failure to recover CMV from healthy human blood donors in spite of predictions of a carrier state based on epidemiologic observations.

Detection of latent cytomegalovirus in murine salivary and prostate explant cultures and cells

After infection of adult mice, cytomegalovirus was detectable in salivary gland suspensions by tissue culture inoculation for up to 3 months. After these cultures had become negative, virus apparently latent in these tissues could be detected in explants of salivary and prostate glands and in cell lines derived from these explants. In some cases cycles of virus-induced cell injury and regrowth were observed. Murine cytomegalovirus plaque efficiency and morphology were evaluated in prostate and salivary gland cell cultures derived from previously infected and uninfected mice. No evidence of interference was detected, although plaques size was altered (larger) in prostate cells from previously infected mice. These studies indicate the presence of a range of suppression, latency, or effects of murine cytomegalovirus detectable after the resolution of active infection and provide methods for additional study of the establishment and activation of virus latency.

Cytomegalovirus replication and the host immune response

Cytomegalovirus (CMV) is closely associated with host cellular structures, and this has a significant impact upon the immunologic response following infection. CMV may be recovered from a variety of body secretions and fluids during acute infection, and protracted shedding may supervene in some instances. The reasons for a variable host response to CMV infection remain unclear, and the mechanisms responsible for the establishment of persistence have not been worked out. CMV persistence and latency are discussed, and some recently derived relevant data are presented. An animal model has been developed consistent with clinical observations pertaining to CMV transmission with blood. Results obtained in the course of these and other studies support the concept of immunological activation of latent CMV. The timing of CMV infection relative to an unrelated antigenic challenge is probably critical in determining the emergence of immunodepression or enhancement. Some aspects of CMV sero-diagnosis are also reviewed.