Proton pump inhibitors alter the composition of the gut microbiota

OBJECTIVE

Proton pump inhibitors (PPIs) are drugs used to suppress gastric acid production and treat GI disorders such as peptic ulcers and gastro-oesophageal reflux. They have been considered low risk, have been widely adopted, and are often over-prescribed. Recent studies have identified an increased risk of enteric and other infections with their use. Small studies have identified possible associations between PPI use and GI microbiota, but this has yet to be carried out on a large population-based cohort.

DESIGN

We investigated the association between PPI usage and the gut microbiome using 16S ribosomal RNA amplification from faecal samples of 1827 healthy twins, replicating results within unpublished data from an interventional study.

RESULTS

We identified a significantly lower abundance in gut commensals and lower microbial diversity in PPI users, with an associated significant increase in the abundance of oral and upper GI tract commensals. In particular, significant increases were observed in Streptococcaceae. These associations were replicated in an independent interventional study and in a paired analysis between 70 monozygotic twin pairs who were discordant for PPI use. We propose that the observed changes result from the removal of the low pH barrier between upper GI tract bacteria and the lower gut.

CONCLUSIONS

Our findings describe a significant impact of PPIs on the gut microbiome and should caution over-use of PPIs, and warrant further investigation into the mechanisms and their clinical consequences.

Magneto-Optical Spectra of Copt3: Experiments and First Principles Calculations

The Magneto-optical Kerr effect of CoPt3 ordered compounds and alloys is investigated experimentally and analyzed theoretically using first principles band structure calculations.

The calculations confirm the experimental results and allow for the first time a detailed, bandstructure based interpretation of the electronic transitions leading to the well known strong uv peak at around 4eV. This feature can be unambiguously attributed to Magneto-optical transitions within the Pt p and d bands.

Does University of Wisconsin solution harm the transplanted heart?

BACKGROUND

University of Wisconsin solution (UW) has been shown to be an effective preservative for the cardiac allograft. Recently, the high potassium content of UW has been implicated in causing coronary endothelial damage, allegedly contributing to development of cardiac allograft vasculopathy (CAV) and eventually to poorer survival.

METHODS

We examined our experience using UW for preservation of cardiac allografts between 1990 and 1994 (n = 94), and compared these to hearts preserved with the lower potassium-containing Stanford solution used at our center between 1986 and 1990 (n = 65). Indices of graft function, ischemic injury, CAV incidence, CAV severity, and survival were evaluated.

RESULTS

The 2 groups were similar in age, gender, diagnosis, donor inotropic support, donor-recipient weight ratio, incidence of acute graft failure, and cytomegalovirus seroconversion. UW-preserved hearts came from older donors (30.5 vs 24.1 years, p < .001), and were transplanted into more status 1 recipients (56% vs 22%, p < .001), consistent with current trends. Mean ischemic time of UW-preserved hearts was significantly longer (184 vs 155 minutes, p < .005) although time required to wean from bypass was less (45.5 vs 73.8 minutes, p < .001) and there was a trend towards less inotropic requirement. CPK-MB release was less with UW preservation (63 vs 87 microg/ dL, p = .001). Three years after transplantation, both groups were similar in the incidence of CAV (UW, 27.3%; STNF, 37.5%; p = 0.27), and also the severity of CAV (p = 0.78). Deaths attributed to CAV were equal in each group (UW, 11.4% vs STNF, 10.7%; p = 0.79). Kaplan-Meier survival analysis revealed equivalent survival curves (p = 0.26).

CONCLUSIONS

We conclude that UW is a safe and effective myocardial preservative, allowing longer ischemic times with equivalent graft function. Our data suggest that when UW is used for cardiac allograft preservation, both CAV and survival are comparable to the experience with other preservatives containing lower concentrations of potassium.

Efficacy of tacrolimus in the treatment of refractory rejection in heart and lung transplant recipients

BACKGROUND

Refractory acute cellular rejection may occur despite triple-drug immunosuppression (cyclosporine A, steroids, azathioprine/mycophenolate mofetil). The purpose of this study was to determine the efficacy of tacrolimus rescue therapy in patients maintained on cyclosporine-based immunosuppression (CBI).

METHODS

Between December 1993 and October 1996, 208 patients underwent thoracic organ transplantation at the Hospital of the University of Wisconsin at Madison. One hundred forty-nine patients underwent heart replacement; 59 underwent lung transplantation. One hundred thirty-nine of the heart transplant cohort received CBI preceded by induction therapy with OKT3. Forty-six of the lung transplant cohort received CBI without induction cytolytic therapy. Refractory rejection was defined as failure to respond to high-dose steroids (500 mg to 1 g IV methylprednisolone for 3 days) and/or monoclonal antibody therapy (OKT3, 5 to 10 mg IV/day for 7 to 14 days). In patients with refractory rejection, cyclosporine was replaced with tacrolimus.

RESULTS

Overall, 16% (30/185) of patients receiving CBI experienced refractory rejection. Thirty-one episodes of grade IIIa or greater rejection occurred in 11% (15/139) of heart transplant recipients. Twenty episodes of grade II to IV rejection occurred in 33% (15/46) of lung transplant recipients. After tacrolimus rescue therapy, 93% (14/15) of patients in the heart transplant group converted to grade II or less rejection. Refractory rejection was reversed in 73% (11/15) of the lung transplant group. Reversal was documented at biopsy in all (8/8) lung recipients in whom it had been histologically identified. FEV1 values of 3 additional patients stabilized.

CONCLUSIONS

The incidence of refractory rejection in thoracic organ transplant recipients on CBI is significant. Reversal of refractory rejection follows rescue immunotherapy with tacrolimus.

The degradation profile of extrachromosomal circular DNA during cisplatin-induced apoptosis is consistent with preferential cleavage at matrix attachment regions

Extrachromosomal circular DNA molecules are prevalent in cancer cells and harbor amplified genes, such as oncogenes and drug resistance genes, that can provide a selective growth advantage to cancer cells. These circular DNA structures include double minute chromosomes (dmin), which can be detected with light microscopy following Giemsa staining, and submicroscopic circular DNA structures referred to as episomes. In this study, we investigated the fate of dmin and episomes in multidrug-resistant human epidermoid KB-VI cells undergoing cisplatin-induced apoptosis-a mode of cell death initially characterized by the fragmentation of chromosomal DNA, while the nuclear membrane remains intact. The circular DNA structures carry amplified copies of the multidrug resistance gene (MDR1). During cisplatin-induced apoptotic cell death, episomes and dmin, as well as native chromosomes, were degraded into high molecular weight DNA fragments of approximately 50 kb in length. DNA fragments in this size range appear to result from the preferential cleavage of matrix-associated regions in chromatin with the subsequent release of 20-30 nm loop domains of chromatin from the nuclear scaffold. Scanning electron microscopy studies were performed and confirmed the presence of 30 nm filaments in a higher-order DNA packing of MDR1-containing dmin and episomes. These combined data provide strong evidence that the higher-order DNA packing of episomes, as well as dmin, is similar to that of native chromosomes and underscore the potential for extrachromosomal DNA amplicons to study the structural and functional organization of chromatin. We discuss the implications of extra-chromosomal DNA matrix associated regions competing with native chromosomal DNA for binding to the nuclear matrix in tumor cells.

Impact of University of Wisconsin solution on clinical heart transplantation. A comparison with Stanford solution for extended preservation

BACKGROUND

The University of Wisconsin Solution (UW) has extended preservation of abdominal organs but has not allowed equally extended preservation of the heart. Therefore, the impact of UW on clinical heart transplantation has remained unclear.

METHODS AND RESULTS

Between June 1986 and March 1994, 161 orthotopic heart transplants were performed at our center. Of these, 66 were preserved for > or = 3 hours. Of these, 17 hearts were preserved with Stanford solution (STNF), which was used before 1990, and 49 were preserved with UW. These groups were compared for indexes of ischemic injury, ventricular function, and survival. The UW group contained more status-1 recipients (57% versus 29%, P < 0.05) and a higher mean donor age (30.7 versus 22.1 years, P = 0.008). Mean ischemic time was slightly but not significantly higher with UW (228 versus 205 minutes for UW versus STNF, respectively; P = 0.085). The time to wean from bypass after cross-clamp removal was nearly twice as long with STNF than with UW (80.6 versus 44.3 minutes, P < 0.001). There was no difference in the incidence of primary graft failure (2% for UW versus 6% for STNF, P = 0.43). The average need for inotropic support over the first 8 posttransplant hours was significantly higher with STNF than UW. Neither hospital stay nor survival differed. Nevertheless, the ability to use donor organs from more distant sites was increased. Of all hearts preserved with STNF, 26% were stored for > or = 3 hours, whereas 51% of all hearts preserved in UW were stored for this length of time. Donor use of hearts increased from 20% in 1989 to 63% in 1993, largely because of greater use of more distant donors.

CONCLUSIONS

We conclude that heart preservation with UW limits ischemic damage from prolonged storage and improves myocardial function in the early posttransplant period, thus allowing greater use of available donors from distant sites to patients awaiting heart transplantation.

Neuroendocrine effects of clonidine in chronic schizophrenic patients under long-term neuroleptic therapy and after drug withdrawal: relations to psychopathology

The sensitivity of the alpha-adrenergic hypothalamic pituitary system, as indicated by growth hormone (GH) release after clonidine (0.15 mg i.v.), was studied in nine chronic schizophrenic in-patients (study 1) under long-term neuroleptic (NL) therapy and after 5 days' drug withdrawal and in 17 chronic schizophrenic in-patients (study 2) under long-term NL therapy and after 12 days' drug withdrawal. GH response after 5- and 12-day drug-free periods did not differ significantly from that under NL treatment; however, it was significantly lower after 12 days' drug withdrawal (AUC: 319.9 +/- 445.5 ng/ml X min) compared to age- and sex-matched normal controls (579 +/- 611 ng/ml X min). The basal norepinephrine (NE) plasma levels under long-term NL therapy were significantly elevated in both studies (study 1:894 +/- 553 pg/ml; study 2:432 +/- 268 pg/ml) compared to controls (study 1:253 +/- 55 pg/ml, study 2:234 +/- 126 pg/ml), and were decreased significantly after 5 days' drug withdrawal compared to NL treatment. There was no significant correlation between age, duration of NL therapy, last daily dosage, psychopathology, and NE plasma levels and GH response. The data presented suggest hyposensitivity of alpha-adrenergic receptor function in the hypothalamic-pituitary axis after 12 days' drug withdrawal in chronic schizophrenics. The significantly elevated NE plasma levels under NL therapy indicate that there is no adaption mechanism, even after long-term treatment.

Neuroendocrine effects of apomorphine in chronic schizophrenic patients under long-term neuroleptic therapy and after drug withdrawal: relations to psychopathology and tardive dyskinesia

The sensitivity of the dopaminergic hypothalamic pituitary system, as indicated by growth hormone (GH) release after apomorphine (0.5 mg SC), was studied in 11 chronic schizophrenic in-patients under long-term neuroleptic (NL) therapy and after 12 and 30 days' drug withdrawal. GH peak levels after a 12-day drug-free period were significantly elevated (13.1 +/- 12 ng/ml) as compared to NL therapy (4.6 +/- 6.1 ng/ml). Controls showed a significant higher mean peak GH response (13.6 +/- 10 ng/ml) compared to chronic schizophrenic patients under long-term NL therapy. The GH response of patients with symptoms of tardive dyskinesia (TD) did not differ significantly from that of patients without signs of TD. The prolactin (PRL) serum levels under long-term NL treatment were within the normal range in male schizophrenics but decreased significantly after 12 days' drug withdrawal. The data presented indicate a reduced sensitivity of the hypothalamic-pituitary dopamine receptors under long-term NL therapy. The significant increase in GH response on day 12 probably corresponds to a readjustment from a mostly blunted GH response under NL therapy back to stimulated levels of normal controls. No supersensitivity of the pituitary dopamine receptors could be detected.

Immunology cross-reactivity between spinal cord protein and myelin basic protein

MyelinMyelinbasic protein-induced experimental allergic encephalitis is prevented or suppressed by pretreating guinea pigs with spinal cord protein. Although myelin basic protein and spinal cord protein do not cross-react at the antibody level, significant cross-stimulation was demonstrated in an antigen-induced lymphocyte proliferation assay. The antigen-sensitive cells were characterized as T lymphocytes in that they were immunoglobulin-negative (Ig-ve) and responded to concanavalin A. However, the level of proliferation observed in the Ig-ve population was much greater than that of undepleted cells. This suggested that there existed an immunoblobulin-bearing suppressor cell population. It was unclear whether T or B lymphocytes were responsible for this suppression in that the Ig+ve cells also responded, to some extent, to concanavalin A, indicating the presence of T cells. Nonetheless, these results suggest that a possible mechanism whereby spinal cord protein protects animals against experimental allergic encephalitis is through the induction of a population of suppressor cells which are sensitized to cross-reactive determinants.

A highly sensitive and precise radioenzymatic assay for plasma epinephrine and norepinephrine

A modification of the procedures for simultaneous radiometric determinations of plasma epinephrine (E) and norepinephrine (NE) was developed. High performance liquid chromatography (HPLC) is excellently suited to separate the radioactive products of the enzymatic methylation of catecholamines. The time-saving procedure shows significant advantages as against the conventional method of isolating normetanephrine and metanephrine by thin layer chromatography. The high sensitivity (detection limit = 1 pg), specifity, and good precision (cv = 6%) of this assay are demonstrated.

Use of a heavy inoculum in the in vitro evaluation of the anti-staphylococcal activity of 19 cephalosporins

The in vitro activity of 19 cephalosporins against 105 clinical isolates of Staphylococcus aureus and S. epidermidis was determined by using a heavy inoculum, i.e., 10(8) to 10(9) organisms per ml, to maximally challenge the antibiotics. The anti-staphylococcal activities of cephaloridine and 87/312 were consistently decreased by the use of a heavy inoculum when compared with the activity obtained with two less-concentrated inocula. The activity of most of the other compounds was also decreased with the use of a heavy inoculum, but this was observed only with selected isolates. Cephapirin, cephalothin, and cefazaflur were the most active drugs against the methicillin-susceptible isolates. Cephaloridine, cefamandole, cefazaflur, and 87/312 had substantial activity against methicillin-resistant staphylococci even with heavy inocula. With the exception of cefaclor against S. aureus, the orally absorbed cephalosporins were generally one-half to one-sixteenth as active as the parenterally administered cephalosporins. The median minimal inhibitory concentrations of five of the 12 parenteral cephalosporins were lower with the methicillin-susceptible S. aureus than with the methicillin-susceptible S. epidermidis strains.