Healthcare-associated carbapenem-resistant Klebsiella pneumoniae infections are associated with higher mortality compared to carbapenem-susceptible K. pneumoniae infections in the intensive care unit: a retrospective cohort study

BACKGROUND

Klebsiella pneumoniae (KP) is an opportunistic pathogen causing severe pneumonia and sepsis. Carbapenem-resistant KP (CRKP) has become a major pathogen in many centres.

AIM

To investigate the association between carbapenem resistance and the mortality rate, length of stay, and hospital cost in patients with Klebsiella pneumoniae infection.

METHODS

The retrospective cohort study was conducted in the intensive care units of a large teaching tertiary hospital in southwest China between January 1st, 2020 and December 31st, 2022. To examine the impact of carbapenem resistance on mortality rates and economic burden, multivariate Cox regression and generalized linear models were constructed.

FINDINGS

The study included 282 adult patients with KP infection (135 CSKP; 147 CRKP). CRKP-infected patients demonstrated higher mortality risk (unadjusted hazard ratio (aHR): 1.980; 95% confidence interval (CI): 1.206-3.248; P = 0.007; aHR: 1.767; 95% CI: 1.038-3.005; P = 0.036) compared to CSKP-infected patients. Stratified analysis, according to type of KP infection, revealed that patients with healthcare-associated CRKP infection had a significantly higher mortality risk compared to those with CSKP infection (log-rank P = 0.015). Patients with CRKP infection had longer hospital stays than those infected with CSKP (adjusted mean: 38.74 vs 29.71 days; P = 0.003), and hospital-related expenses were notably higher among CRKP patients than CSKP patients (adjusted cost: £40,126.73 vs 25,713.74; P < 0.001).

CONCLUSION

CRKP infections increase mortality rates, prolong hospital stays, and raise healthcare costs. Healthcare facilities should adopt targeted strategies, including curtailing pre-infection hospitalization periods and managing medications more judiciously.

Diagnosis for Chinese patients with light chain amyloidosis: a scoping review

BACKGROUND

Amyloid light chain (AL) amyloidosis is the most common systemic amyloidosis. The objective of this scoping review was to map the available literature on the diagnosis of AL amyloidosis in China.

MATERIALS AND METHODS

The published academic papers related to the diagnosis of AL amyloidosis were screened from 1 January 2000 to 15 September 2021. Chinese patients who have suspected AL amyloidosis were included. The included studies were categorized into accuracy studies and descriptive studies based on if the studies supplied the diagnostic accuracy data or not. The information on the diagnostic methods reported by included studies was synthesized.

RESULTS

Forty-three articles were included for the final scoping review, with 31 belonging to descriptive studies and 12 having information on diagnostic accuracy. Although cardiac involvement was second top in Chinese patients with AL amyloidosis, a cardiac biopsy was rare. Next, we found light chain classification and monoclonal (M-) protein identification were essential methods for the diagnosis of AL amyloidosis in China. In addition, some combined tests (e.g. immunohistochemistry and serum free light chain, immunohistochemistry and immunofixation electrophoresis, and serum free light chain and immunofixation electrophoresis) can increase the sensitivity of the diagnosis. Finally, several adjuvant methods (e.g. Imaging, N-terminal-pro hormone BNP, and brain natriuretic peptide test) were important for AL amyloidosis diagnosis.

CONCLUSION

This scoping review details the characteristics and results of the recently published studies on diagnosing AL Amyloidosis in China. Biopsy is the most important method for AL Amyloidosis diagnosis in China. In addition, combined tests and some adjuvant methods played essential roles in the diagnosis. Further research is required to determine an acceptable and feasible diagnostic algorithm after symptom onset. REGISTRATION: INPLASY2022100096KEY MESSAGESThis scoping review details the characteristics and results of the recently published studies on diagnosing Amyloid light chain (AL) Amyloidosis in China.Biopsy is the most important method for AL Amyloidosis diagnosis in China.Combined tests and some adjuvant methods played essential roles in the diagnosis.

m6 A Reader YTHDF1-Targeting Engineered Small Extracellular Vesicles for Gastric Cancer Therapy via Epigenetic and Immune Regulation

N⁶ -methyladenosine (m⁶ A) modulators decide the fate of m⁶ A-modified transcripts and drive cancer development. RNA interference targeting m⁶ A modulators promise to be an emerging cancer therapy but is challenging due to its poor tumor targeting and high systematic toxicity. Here engineered small extracellular vesicles (sEVs) with high CD47 expression and cyclic arginine-glycine-aspartic (c(RGDyC)) modification are developed for effective delivery of short interfering RNA against m⁶ A reader YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) to treat gastric cancer via epigenetic and immune regulation. This nanosystem efficiently depletes YTHDF1 expression and suppresses gastric cancer progression and metastasis through hampering frizzled7 translation and inactivating Wnt/β-catenin pathway in an m⁶ A dependent manner. Loss of YTHDF1 mediates overexpression of interferon (IFN)-γ receptor 1 and enhances IFN-γ response, promoting expression of major histocompatibility complex class I on tumor cells to achieve self-presentation of the immunogenic tumor cells to stimulate strong cytotoxic T lymphocytes responses. CD47 expression on the engineered sEVs can competitively bind with signal regulatory protein α to enhance phagocytosis of the tumor cells by tumor-associated macrophages. This versatile nanoplatform provides an efficient and low toxic strategy to inhibit epigenetic regulators and holds great potential in promoting immunotherapy.

METTL3 preferentially enhances non-m6A translation of epigenetic factors and promotes tumourigenesis

METTL3 encodes the predominant catalytic enzyme to promote m⁶A methylation in nucleus. Recently, accumulating evidence has shown the expression of METTL3 in cytoplasm, but its function is not fully understood. Here we demonstrated an m⁶A-independent mechanism for METTL3 to promote tumour progression. In gastric cancer, METTL3 could not only facilitate cancer progression via m⁶A modification, but also bind to numerous non-m⁶A-modified mRNAs, suggesting an unexpected role of METTL3. Mechanistically, cytoplasm-anchored METTL3 interacted with PABPC1 to stabilize its association with cap-binding complex eIF4F, which preferentially promoted the translation of epigenetic factors without m⁶A modification. Clinical investigation showed that cytoplasmic distributed METTL3 was highly correlated with gastric cancer progression, and this finding could be expanded to prostate cancer. Therefore, the cytoplasmic METTL3 enhances the translation of epigenetic mRNAs, thus serving as an oncogenic driver in cancer progression, and METTL3 subcellular distribution can assist diagnosis and predict prognosis for patients with cancer.

YTHDF1 Promotes Gastric Carcinogenesis by Controlling Translation of FZD7

N⁶-methyladenosine (m⁶A) is the most prevalent internal RNA modification in mammals that regulates homeostasis and function of modified RNA transcripts. Here, we aimed to investigate the role of YTH m⁶A RNA-binding protein 1 (YTHDF1), a key regulator of m⁶A methylation in gastric cancer tumorigenesis. Multiple bioinformatic analyses of different human cancer databases identified key m⁶A-associated genetic mutations that regulated gastric tumorigenesis. YTHDF1 was mutated in about 7% of patients with gastric cancer, and high expression of YTHDF1 was associated with more aggressive tumor progression and poor overall survival. Inhibition of YTHDF1 attenuated gastric cancer cell proliferation and tumorigenesis in vitro and in vivo. Mechanistically, YTHDF1 promoted the translation of a key Wnt receptor frizzled7 (FZD7) in an m⁶A-dependent manner, and mutated YTHDF1 enhanced expression of FZD7, leading to hyperactivation of the Wnt/β-catenin pathway and promotion of gastric carcinogenesis. Our results demonstrate the oncogenic role of YTHDF1 and its m⁶A-mediated regulation of Wnt/β-catenin signaling in gastric cancer, providing a novel approach of targeting such epigenetic regulators in this disease. SIGNIFICANCE: This study provides a rationale for controlling translation of key oncogenic drivers in cancer by manipulating epigenetic regulators, representing a novel and efficient strategy for anticancer treatment. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/10/2651/F1.large.jpg.

The m6A reader YTHDF1 promotes ovarian cancer progression via augmenting EIF3C translation

N⁶-Methyladenosine (m⁶A) is the most abundant RNA modification in mammal mRNAs and increasing evidence suggests the key roles of m⁶A in human tumorigenesis. However, whether m⁶A, especially its ‘reader’ YTHDF1, targets a gene involving in protein translation and thus affects overall protein production in cancer cells is largely unexplored. Here, using multi-omics analysis for ovarian cancer, we identified a novel mechanism involving EIF3C, a subunit of the protein translation initiation factor EIF3, as the direct target of the YTHDF1. YTHDF1 augments the translation of EIF3C in an m⁶A-dependent manner by binding to m⁶A-modified EIF3C mRNA and concomitantly promotes the overall translational output, thereby facilitating tumorigenesis and metastasis of ovarian cancer. YTHDF1 is frequently amplified in ovarian cancer and up-regulation of YTHDF1 is associated with the adverse prognosis of ovarian cancer patients. Furthermore, the protein but not the RNA abundance of EIF3C is increased in ovarian cancer and positively correlates with the protein expression of YTHDF1 in ovarian cancer patients, suggesting modification of EIF3C mRNA is more relevant to its role in cancer. Collectively, we identify the novel YTHDF1-EIF3C axis critical for ovarian cancer progression which can serve as a target to develop therapeutics for cancer treatment.

Genome-wide association study confirms that the chromosome Z harbours a region responsible for rumplessness in Hongshan chickens

Rumplessness in Hongshan chickens has been reported as a novel sex-linked characteristic. Re-sequencing data suggest that a pseudogene on the Z chromosome, LOC431648, is affiliated with this phenotype. In this study, we chose 23 rumpless and 25 normal Hongshan chickens to localize the potential variation by means of a genome-wide association study using a high density microarray. A region on the Z chromosome was found to be closely associated with rumplessness in Hongshan chickens. The region, located in gene LINGO2, was approximately 3 Mb away from pseudogene LOC431648. The function of this gene has not yet been studied in birds. Differential expression of the candidate genes in the tail feather follicles was not detected by q-PCR, which suggests that the rumplessness trait could be attributed to other genetic mechanisms.

[Knockdown of YTH N6-methyladenosine RNA binding protein 2 (YTHDF2) inhibits proliferation and promotes apoptosis in MGC-803 gastric cancer cells]

Objective To investigate the effect of knockdown of YTH N⁶-methyladenosine RNA binding protein 2 (YTHDF2) on cell proliferation, cell cycle and apoptosis of MGC-803 human gastric cancer cells in vitro. Methods The TCGA database was downloaded from UCSC Cancer Browser and to search for the differential expressions of YTHDF2 mRNA in gastric cancer tissues. Short hairpin RNA (shRNA) targeting YTHDF2 was designed and cloned into lentivirus expression vector pLKO.1. Furthermore, MGC-803 gastric cancer cells were transfected with pLKO.1-shRNA to knockdown the expression of YTHDF2, which was confirmed by the detection of YTHDF2 mRNA and protein expression using real-time quantitative PCR and Western blotting, respectively. Then cell proliferation was observed by CCK-8 assay, and cell cycle and apoptosis were examined by flow cytometry. Results According to the TCGA database, the expression of YTHDF2 mRNA in gastric cancer was significantly higher than that in the normal tissues. MGC-803 stably expressing YTHDF2-shRNA was successfully established. Furthermore, the proliferation capacity of YTHDF2-shRNA-expressing MGC-803 cells was significantly inhibited compared with the controls. Similarly, the percentage of YTHDF2-shRNA-expressing MGC-803 cells in G1 phase increased and in S phase decreased compared with the controls. Meanwhile, apoptosis ratio of YTHDF2-shRNA-expressing MGC-803 cells was significantly higher compared with the control groups. Conclusion Knockdown of YTHDF2 in MGC-803 cells inhibits cell proliferation and promotes apoptosis.

Reactive oxygen species and uncoupling protein 2 in pancreatic β-cell function

Growing evidence indicates that reactive oxygen species (ROS) are not just deleterious by-products of respiratory metabolism in mitochondria, but can be essential elements for many biological responses, including in pancreatic β-cells. ROS can be a 'second-messenger signal' in response to hormone/receptor activation that serves as part of the 'code' to trigger the ultimate biological response, or it can be a 'protective signal' to increase the levels of antioxidant enzymes and small molecules to scavenge ROS, thus restoring cellular redox homeostasis. In pancreatic β-cells evidence is emerging that acute and transient glucose-dependent ROS contributes to normal glucose-stimulated insulin secretion (GSIS). However, chronic and persistent elevation of ROS, resulting from inflammation or excessive metabolic fuels such as glucose and fatty acids, may elevate antioxidant enzymes such that they blunt ROS and redox signalling, thus impairing β-cell function. An interesting mitochondrial protein whose main function appears to be the control of ROS is uncoupling protein 2 (UCP2). Despite continuing investigation of the exact mechanism by which UCP2 is 'activated', it is clear that UCP2 levels and/or activity impact the efficacy of GSIS in pancreatic islets. This review will focus on the paradoxical roles of ROS in pancreatic β-cell function and the regulatory role of UCP2 in ROS signalling and GSIS.

Breakthrough fungal infections after allogeneic hematopoietic stem cell transplantation in patients on prophylactic voriconazole

Seventy-one allograft recipients receiving voriconazole, in whom complete clinical, microbiologic and pharmacokinetic data were available, were studied to determine the efficacy of voriconazole in preventing fungal infections. The length of voriconazole therapy was 6-956 days (median 133). The total number of patient-days on voriconazole was 13 805 ( approximately 38 years). A total of 10 fungal infections were seen in patients on voriconazole (18% actuarial probability at 1 year): Candida glabrata (n=5), Candida krusei (n=1), Cunninghamella (n=1), Rhizopus (n=2) and Mucor (n=1). Two of the four zygomycosis cases were preceded by short durations of voriconazole therapy, but prolonged itraconazole prophylaxis. The plasma steady-state trough voriconazole levels around the time the infection occurred were <0.2, <0.2, 0.33, 0.55, 0.63 and 1.78 microg/ml in the six candidiasis cases. Excluding the four zygomycosis cases, all the six candidiasis cases were seen among the 43 patients with voriconazole levels of < or =2 microg/ml and none among the 24 with levels of >2 microg/ml (P=0.061). We conclude that voriconazole is effective at preventing aspergillosis. However, breakthrough zygomycosis is seen in a small proportion of patients. The role of therapeutic voriconazole monitoring with dose adjustment to avoid breakthrough infections with fungi that are otherwise susceptible to the drug needs to be explored prospectively.

Reduced-dose rasburicase (recombinant xanthine oxidase) in adult cancer patients with hyperuricemia

Recombinant urate oxidase (rasburicase) lowers uric acid levels rapidly to very low levels at the labeled dose of 0.15-0.2 mg/kg daily for 5 days. Our past experience showed that a lower dose (3 mg) lowered uric acid levels sufficiently in most patients. A retrospective review was conducted to determine the effect of a fixed 3 mg dose of rasburicase in 43 adult patients with cancer undergoing hematopoietic stem cell transplantation or receiving chemotherapy who had elevated or rising uric acid levels (6.4-16.8 mg/dl; median 9.6). Six patients received a second dose of rasburicase (3 mg in four patients and 1.5 mg in two patients) 24 h later. Patients received allopurinol, adequate hydration, as well as other supportive therapy as required. Uric acid levels declined by 6-95% (median 43%) within the first 24 h after rasburicase administration, and levels at 48 h were 9-91% (median 65%) lower than the baseline levels. Serum creatinine changed by < or =10% in 21 patients, increased by >10% in four patients and decreased by >10% in 18 patients. No significant renal dysfunction developed in any of the patients. We conclude that rasburicase is effective in lowering uric acid levels at a fixed dose of 3 mg, which is much lower than the recommended dose.

Chronic UVA irradiation of human HaCaT keratinocytes induces malignant transformation associated with acquired apoptotic resistance

Ultraviolet A (UVA, 315-400 nm), constituting about 95% of ultraviolet irradiation in natural sunlight, represents a major environmental challenge to the skin and is clearly associated with human skin cancer. It has proven difficult to show direct actions of UVA as a carcinogen in human cells. Here, we demonstrate that chronic UVA exposures at environmentally relevant doses in vitro can induce malignant transformation of human keratinocytes associated with acquired apoptotic resistance. As evidence of carcinogenic transformation, UVA-long-treated (24 J/cm(2) once/week for 18 weeks) HaCaT (ULTH) cells showed increased secretion of matrix metalloproteinase (MMP-9), overexpression of keratin 13, altered morphology and anchorage-independent growth. Malignant transformation was established by the production of aggressive squamous cell carcinomas after inoculation of ULTH cells into nude mice (NC(r)-nu). ULTH cells were resistant to apoptosis induced not only by UVA but also by UVB and arsenite, two other human skin carcinogens. ULTH cells also became resistant to apoptosis induced by etoposide, staurosporine and doxorubicin hydrochloride. Elevated phosphorylation of protein kinase B (PKB, also called AKT) and reduced expression of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) were detected in ULTH cells. The resistance of ULTH cells to UVA-induced apoptosis was reversed by either inhibition of phosphatidylinositol 3-kinase (PI-3K) or adenovirus expression of PTEN or dominant negative AKT. These data indicate that UVA has carcinogenic potential in human keratinocytes and that the increased AKT signaling and decreased PTEN expression may contribute to this malignant transformation. Further comparisons between the transformed ULTH and control cells should lead to a better understanding of the mechanism of UVA carcinogenesis and may help identify biomarkers for UVA-induced skin malignancies.

Voriconazole therapeutic drug monitoring in allogeneic hematopoietic stem cell transplant recipients

Voriconazole, a new antifungal agent, is increasingly being used after HSCT. The hepatic cytochrome P450 isoenzyme 2C19 plays a significant role in voriconazole metabolism. As CYP2C19 exhibits significant genetic polymorphism, some patients metabolize voriconazole poorly resulting in increased plasma drug levels. The clinical significance of this is unknown, and the utility of monitoring voriconazole levels is unclear. Steady-state trough plasma voriconazole levels were obtained in 25 allogeneic HSCT recipients using an HPLC assay. Patients had drug levels checked once (n=13), twice (n=10), or > or =3 times (n=2) 5-18 days (median 10) after starting voriconazole or dose modification. The 41 voriconazole levels were 0.2-6.8 microg/ml (median 1.6); 6 (15%) were <0.5 (possibly below the in vitro MIC90 for Aspergillus spp.). Voriconazole concentrations correlated with aspartate aminotranferase (AST) (r=0.5; P=0.0009) and alkaline phosphatase (r=0.34; P=0.03), but not with creatinine, bilirubin and alanine aminotransferase (ALT). Since liver dysfunction is common after HSCT, it was not possible to determine if elevated AST and alkaline phosphatase levels were the cause or the consequence of higher voriconazole levels. We conclude that trough voriconazole levels vary considerably between patients, and suggest monitoring levels in patients receiving voriconazole for confirmed fungal infections, and in those with elevated AST or alkaline phosphatase levels.

Putative interhelical interactions within the PheP protein revealed by second-site suppressor analysis

Highly conserved glycine residues within span I and span II of the phenylalanine and tyrosine transporter PheP were shown to be important for the function of the wild-type protein. Replacement by amino acids with increasing side chain volume led to progressive loss of transport activity. Second-site suppression studies performed with a number of the primary mutants revealed a tight packing arrangement between spans I and II that is important for function and an additional interaction between spans I and III. We also postulate that a third motif, GXXIG, present in span I and highly conserved within different members of the amino acid-polyamine-organocation family, may function as a dimerization motif. Surprisingly, other highly conserved residues, such as Y60 and L41, could be replaced by various residues with no apparent loss of activity.

Influence of bed preparation on the incorporation of autogenous bone grafts: a study in dogs

To study the influence of bed preparation on the incorporation of autogenous bone grafts in mandibles, 6 dogs with 3 different types of receptor bed were used: cortical, perforated, and decorticated. After 45 and 90 days, the animals were sacrificed and block sections of grafted and adjacent bone were removed. The specimens were prepared and stained with hematoxylin and eosin and Masson's trichromic. The autogenous bone grafts were integrated with the receptor bed, mainly in the perforated and decorticated groups. The poorest results were found in the cortical group.

Improved method for simultaneous determination of L-arginine and its mono- and dimethylated metabolites in biological samples by high-performance liquid chromatography

An improved method has been developed for the determination of L-arginine and its methylated metabolites, N(G)-monomethyl-L-arginine (L-NMMA), N(G),N(G)-dimethyl-L-arginine (asymmetric DMA, ADMA) and N(G),N(G)'-dimethyl-L-arginine (symmetric DMA, SDMA) in biological samples. Extraction of these compounds with a strong cation-exchange resin AG50W-X8 with L-homoarginine (2-amino-6-guanidinohexanoic acid) as an internal standard gave a recovery of more than 70% except for SDMA from plasma samples. After extracted samples were converted to fluorescent derivatives with o-phthalaldehyde (OPA) in an alkaline medium, the following high-performance liquid chromatographic separation with a ODS column (wide-pore size, 300 A) was successfully performed with an isocratic mobile phase system. The method permits quantitative determination of L-arginine and its methylated metabolites at concentrations as low as 4 microM and 0.18 microM, respectively. Using this method, the levels of L-arginine, L-NMMA, ADMA and SDMA in human plasma, urine and rat tissue were determined.

A study of AroP-PheP chimeric proteins and identification of a residue involved in tryptophan transport

In vivo recombination has been used to make a series of AroP-PheP chimeric proteins. Analysis of their respective substrate profiles and activities has identified a small region within span III of AroP which can confer on a predominantly PheP protein the ability to transport tryptophan. Site-directed mutagenesis of the AroP-PheP chimera, PheP, and AroP has established that a key residue involved in tryptophan transport is tyrosine at position 103 in AroP. Phenylalanine is the residue at the corresponding position in PheP. The use of PheP-specific antisera has shown that the inability of certain chimeras to transport any of the aromatic amino acids is not a result of instability or a failure to be inserted into the membrane. Site-directed mutagenesis has identified two significant AroP-specific residues, alanine 107 and valine 114, which are the direct cause of loss of transport activity in chimeras such as A152P. These residues replace a glycine and an alanine in PheP and flank a highly conserved glutamate at position 110. Some suggestions are made as to the possible functions of these residues in the tertiary structure of the proteins.

Decreased serum concentrations of nitric oxide metabolites among Chinese in an endemic area of chronic arsenic poisoning in inner Mongolia

Prolonged exposure to arsenic results in peripheral and cardiovascular manifestations, as does impaired production of endothelial nitric oxide (NO). In vitro studies have indicated that endothelial cells undergo damage by arsenic. However, no information has been available on the relationship between NO synthesis and chronic arsenic poisoning in humans. The present study was designed to reveal this question. The subjects were 33 habitants who continued to drink well water containing high concentrations of inorganic arsenic (mean value = 0.41 microg/ml) for about 18 years in Inner Mongolia, China, and 10 other people who lived in this area but exposed to minimal concentrations of arsenic (mean value = 0.02 microg/ml) were employed as controls. Mean blood concentration of total arsenic was six times higher in exposed subjects than controls; 42.1 vs. 7.3 ng/ml, p <.001. Mean serum concentration of nitrite/nitrate, stable metabolites of endogenous NO, was lower in arsenic-exposed subjects than in controls: 24.7 vs. 51.6 microM, p<.001. In total samples, an inverse correlation with serum nitrite/nitrate levels was strong for blood inorganic arsenic (r = -0.52, p <.001) and less strong for its metabolites, monomethyl arsenic (r = -0.45, p<.005) and dimethyl arsenic (r = -0.37, p<.05). Furthermore, serum nitrite/nitrate concentration was significantly correlated with nonprotein sulfhydryl level in whole blood (r = 0.58, p<.001). In an in vitro study, we demonstrated that inorganic arsenite or arsenate suppresses the activity of endothelial NO synthase in human umbilical vein endothelial cells. These results suggest that long-term exposure to arsenic by drinking well water possibly reduces NO production in endothelial cells, resulting in a decrease in reduced nitrite/nitrate concentrations. Peripheral vascular disorders caused by arsenic may be attributable in part to impairment of NO production in vivo.

[Cardiac manifestations of primary hypothyroidism. Determinant factors and treatment response]

INTRODUCTION AND OBJECTIVES

Previous studies have not fully established the magnitude and determinant factors of cardiac manifestations of primary hypothyroidism. This study was aimed to assess the effects of thyroid deficiency on cardiac performance and structure.

PATIENTS AND METHODS

We studied by echocardiography 19 patients with overt and 23 with subclinical hypothyroidism, and 21 control subjects. Patients were restudied one year after L-thyroxine therapy. Systolic function was assessed by the observed/predicted fractional shortening ratio. The predicted fractional shortening was calculated from the inverse relation of fractional shortening to end-systolic stress (p < 0.0001) in normal subjects.

RESULTS

The observed/predicted fractional shortening ratio was lower (p = 0.043) and left ventricular mass was higher (p = 0.028) in overt hypothyroidism than in subclinical hypothyroidism and control subjects. By multivariate analysis, fractional shortening ratio was related to thyroxine levels (p = 0.0002), systemic vascular resistance (p = 0.0001) and age (p = 0.0009), and left ventricular mass was related to thyroxine levels (p = 0.0004) and weight (p = 0.0001). Pericardial effusion was observed in 37% of patients with overt hypothyroidism and 9% of patients with subclinical hypothyroidism (p = 0.03), and was mainly related to TSH levels (p = 0.0098). Hormone replacement therapy increased systolic function in overt hypothyroidism. Left ventricular mass did not change after therapy. Pericardial effusion disappeared in all patients.

CONCLUSIONS

Primary hypothyroidism produces a decrease in myocardial contractility and an increase in left ventricular mass, both related to the severity of hormone deficiency. Pericardial effusion is mainly related to thyrotrophin plasma levels. Most of cardiac manifestations of hypothyroidism reverse with L-thyroxine therapy.

Functional consequences of changing proline residues in the phenylalanine-specific permease of Escherichia coli

The PheP protein is a high-affinity phenylalanine-specific permease of the bacterium Escherichia coli. A topological model based on genetic analysis involving the construction of protein fusions with alkaline phosphatase has previously been proposed in which PheP has 12 transmembrane segments with both N and C termini located in the cytoplasm (J. Pi and A. J. Pittard, J. Bacteriol. 178:2650-2655, 1996). Site-directed mutagenesis has been used to investigate the functional importance of each of the 16 proline residues of the PheP protein. Replacement of alanine at only three positions, P54, P341, and P442, resulted in the loss of 50% or more activity. Substitutions at P341 had the most dramatic effects. None of these changes in transport activity were, however, associated with any defect of the mutant protein in inserting into the membrane, as indicated by [35S]methionine labelling and immunoprecipitation using anti-PheP serum. A possible role for each of these three prolines is discussed. Inserting a single alanine residue at different sites within span IX and the loop immediately preceding it also had major effects on transport activity, suggesting an important role for a highly organized structure in this region of the protein.

[Protective effects of exogenous superoxide dismutase on rabbit retinal injury by acute intraocular hypertension]

OBJECTIVE

To study active oxygen and free radical injury in rabbit retina during elevated intraocular pressure and the protective effect of exogenous superoxide dismutase (SOD) on the retinal damage by the hypertension.

METHODS

Lipid peroxidative product, malondialdehyde (MDA), activity of SOD and glutathione peroxidase (GSH-Px), reduced GSH in the retinal tissue were measured during 24 h after the release of an ocular hypertension, 6.67 kPa (1 kPa = 7.5 mmHg) maintaining for 1.5 h, and the effects of retrobulbarly injected Cu-Zn-SOD on the level of MDA and the activity of SOD in the retinal tissue after the release of ocular hypertension for 12 h were observed.

RESULTS

MDA increased gradually during 0-12 h after the release of ocular hypertension and maintained at a relatively high level in 12-24 h. The activity of SOD and GSH-Px was lower than normal level immediately after the release, and then increased to a certain different extent. But the activity of SOD began to decrease gradually 4 h after the release. GSH had no significant changes during 24 h after the release. Retrobulbar injection of Cu-Zn-SOD reduced the production of MDA in the retinal tissue and enhanced SOD activity.

CONCLUSIONS

Active oxygen and free radicals participate the rabbit retinal injury by elevated intraocular pressure. A high dose of Cu-Zn-SOD retrobulbar injection plays a beneficial role in enhancing the antioxidative ability of the retina.

[A study on relationship between glutathione S-transferase mu gene deletion and senile cataract susceptibility]

OBJECTIVE

To study the relationship between glutathione S-transferase mu (GST mu) gene deletion and senile cataract (SC) susceptibility.

METHOD

Polymerase chain reaction (PCR) method was used to investigate the rates of GST mu gene deletion in 59 cases with SC and 112 healthy controls.

RESULTS

The rate of GST mu gene deletion in cases with SC was 69.5% which was significantly higher than that of the controls, 50.9% (P < 0.05). An analysis stratified by smoking and nonsmoking showed that GST mu gene deletion rate in smoking subjects with SC was higher. Because of the small sample size of this study, although the rate of GST mu gene deletion in smoking subjects with SC has reached 72.4%, that is not significantly different from that of the controls statistically (P > 0.05).

CONCLUSION

SC correlates with GST mu gene deletion and GST mu gene deletion is one of the hereditary factors for susceptibility to SC.

Topology of the phenylalanine-specific permease of Escherichia coli

The PheP protein is a high-affinity phenylalanine-specific permease of the bacterium Escherichia coli. A topological model based on sequence analysis of the putative protein in which PheP has 12 transmembrane segments with both N and C termini located in the cytoplasm had been proposed (J. Pi, P. J. Wookey, and A. J. Pittard, J. Bacteriol. 173:3622-3629, 1991). This topological model of PheP has been further examined by generating protein fusions with alkaline phosphatase. Twenty-five sandwich fusion proteins have been constructed by inserting the 'phoA gene at specific sites within the pheP gene. In general, the PhoA activities of the fusions support a PheP topology model consisting of 12 transmembrane segments with the N and C termini in the cytoplasm. However, alterations to the model, affecting spans III and VI, were indicated by this analysis and were supported by additional site-directed mutagenesis of some of the residues involved.

[The relationship between the high inducibility genotype of CYP450IA1 and lung cancer susceptibility]

OBJECTIVE

To evaluate the role of polymorphism of CYP450IA1 gene in the susceptibility of lung cancer.

METHODS

The polymorphism of CYP450IA1 gene in 149 lung cancer patients and 208 healthy controls were investigated by PCR technique.

RESULTS

The high inducibility genotype (Val/Val type) of CYP450IA1 in lung cancer patients was 16.1%, which was significantly higher than that of controls, 8.7%. According to pathological classification of lung cancer, it was indicated that VAl/Val type in squamous carcinomas was the highest, 21.54%, which was significantly higher than that of controls (8.7%) and adenocarcinomas (8.00%). The Val/Val type in small cell carcinoma reached 17.6%. The relative risks were estimated according to smoking condition and CYP450IA1 genotype. Taking the risk of the category with non-smoking and non-high inducibility genotype (Val/ Val) to be at a baseline of 1.0, the odds ratio was 1.6 (P < 0.05) in non-smoking in non-smoking and Val/Val type 4.8 in smoking and Val/Val type (P < 0.001). The relative risk of Val/Val type was 2.2 times as non-Val/ Val type for smoking people.

CONCLUSIONS

Development of lung cancer was associated with the high inducibility genotype of CYP450IA1. And Val/Val genotype of CYP450IA1 gene might be an important host hereditary marker for susceptibility to lung cancer.

Prevalence of dementia in a semi-rural population of Catalunya, Spain

This study was to investigate the prevalence of dementia in an aging population. A two-phase model was used to obtain information on the socio-demographic, medical and cognitive status of subjects over 65 years of age (n = 516), resident on December 31, 1990, within the general population (n = 3,457) of La Selva del Camp. A diagnostic protocol, following the criteria of DSM-III, was designed for application to all subjects. We diagnosed 64 subjects with dementia, which represented a prevalence of 14.9% of which 3.2% was classified as severe, 4.5% as moderate and 7.3% as slight. The prevalence by age and sex showed a large increase with age and a higher prevalence in females, although the latter was not statistically significant.

[The study of GST mu gene deletion as the hereditary marker for susceptibility to lung cancer]

A total of 175 lung cancer patients and 104 controls were detected for GST mu gene using PCR technique. The results showed that the GST mu gene deletion rate in lung cancer patients was 71.4%, which was significantly higher than the controls, 51.9%. Analysis according to pathological classification of lung cancer indicated that the GST mu gene deletion rate in all three kinds of pathological types-squamous, adenocarcinoma and small cell carcinoma, were markedly higher than that of controls, especially for small cell carcinoma (the deletion sate is 77.5%). The frequency of GST mu gene was not associated with smoking in both groups, but the higher deficiency rate was found in the low age group of lung cancer patients, showed 85.3% compared to the high age group, 68.1%. All the results showed that GST mu gene deletion may be an important host hereditary marker for susceptibility to lung cancer.

[Mini Mental State Examination: association of the score obtained with the age and degree of literacy in an aged population]

BACKGROUND

To differentiate dementia from the normal human decline scales may be used in an attempt to identity and quantify the cognitive damage which a subject may present. The Mini Mental State Examination (MMSE) is one of those. This study was performed to identify the relation of the responses between the MMSE and the sociodemographic variables of the subjects.

METHODS

The MMSE was applied as a tool to determine the presence of cognitive alterations in a prospective study of people over the age of 65 years from La Selva del Camp (Baix Camp, Catalonia, Spain). The population was differentiated according to the cut off point (24 points) with the relation of the score obtained by each subjects being studied with the sociodemographic variables of the same.

RESULTS

The mean score obtained in the test by the total population was: (mean +/- SD) 23.9 +/- 4.5 points; 24.6 +/- 4.9 in the males and 22.5 +/- 5.8 in the females. In the age group 65-74 years the mean score was 24.8 +/- 3.8; 23 +/- 4.6 in those from 75-80 years and 21.4 +/- 6 in the age group over 85 years. Sex was significantly associated (p = 0.0003), as were age (p = 0.0002) and the degree of alphabetization (p = 0.0000) with women obtaining a lower MMSE score than men, the most elderly was lower than that obtained by the younger and those of less alphabetization lower than those with education.

CONCLUSIONS

Although the MMSE is a good tool for the detection of cognitive alterations in a population, it must be kept in mind that the result of this test may be influenced by the age and education of the subject and should therefore not be used as an exclusive element in the diagnosis of dementia.

Site-directed mutagenesis reveals the importance of conserved charged residues for the transport activity of the PheP permease of Escherichia coli

Site-directed mutagenesis has been used to identify a number of charged residues essential for the transport activity of the PheP protein. These residues are highly conserved in the cluster of amino acid transporters. However, some other conserved residues and a number of aromatic residues have been shown not to be essential for transport activity.

Cloning and sequencing of the pheP gene, which encodes the phenylalanine-specific transport system of Escherichia coli

The phenylalanine-specific permease gene (pheP) of Escherichia coli has been cloned and sequenced. The gene was isolated on a 6-kb Sau3AI fragment from a chromosomal library, and its presence was verified by complementation of a mutant lacking the functional phenylalanine-specific permease. Subcloning from this fragment localized the pheP gene on a 2.7-kb HindIII-HindII fragment. The nucleotide sequence of this 2.7-kb region was determined. An open reading frame was identified which extends from a putative start point of translation (GTG at position 636) to a termination signal (TAA at position 2010). The assignment of the GTG as the initiation codon was verified by site-directed mutagenesis of the initiation codon and by introducing a chain termination mutation into the pheP-lacZ fusion construct. A single initiation site of transcription 30 bp upstream of the start point of translation was identified by the primer extension analysis. The pheP structural gene consists of 1,374 nucleotides specifying a protein of 458 amino acid residues. The PheP protein is very hydrophobic (71% nonpolar residues). A topological model predicted from the sequence analysis defines 12 transmembrane segments. This protein is highly homologous with the AroP (general aromatic transport) system of E. coli (59.6% identity) and to a lesser extent with the yeast permeases CAN1 (arginine), PUT4 (proline), and HIP1 (histidine) of Saccharomyces cerevisiae.