Clinical characteristics of COVID-19-infected cancer patients: a retrospective case study in three hospitals within Wuhan, China

Background

Cancer patients are regarded as a highly vulnerable group in the current Coronavirus Disease 2019 (COVID-19) pandemic. To date, the clinical characteristics of COVID-19-infected cancer patients remain largely unknown.

Patients and methods

In this retrospective cohort study, we included cancer patients with laboratory-confirmed COVID-19 from three designated hospitals in Wuhan, China. Clinical data were collected from medical records from 13 January 2020 to 26 February 2020. Univariate and multivariate analyses were carried out to assess the risk factors associated with severe events defined as a condition requiring admission to an intensive care unit, the use of mechanical ventilation, or death.

Results

A total of 28 COVID-19-infected cancer patients were included; 17 (60.7%) patients were male. Median (interquartile range) age was 65.0 (56.0–70.0) years. Lung cancer was the most frequent cancer type (n = 7; 25.0%). Eight (28.6%) patients were suspected to have hospital-associated transmission. The following clinical features were shown in our cohort: fever (n = 23, 82.1%), dry cough (n = 22, 81%), and dyspnoea (n = 14, 50.0%), along with lymphopaenia (n = 23, 82.1%), high level of high-sensitivity C-reactive protein (n = 23, 82.1%), anaemia (n = 21, 75.0%), and hypoproteinaemia (n = 25, 89.3%). The common chest computed tomography (CT) findings were ground-glass opacity (n = 21, 75.0%) and patchy consolidation (n = 13, 46.3%). A total of 15 (53.6%) patients had severe events and the mortality rate was 28.6%. If the last antitumour treatment was within 14 days, it significantly increased the risk of developing severe events [hazard ratio (HR) = 4.079, 95% confidence interval (CI) 1.086–15.322, P = 0.037]. Furthermore, patchy consolidation on CT on admission was associated with a higher risk of developing severe events (HR = 5.438, 95% CI 1.498–19.748, P = 0.010).

Conclusions

Cancer patients show deteriorating conditions and poor outcomes from the COVID-19 infection. It is recommended that cancer patients receiving antitumour treatments should have vigorous screening for COVID-19 infection and should avoid treatments causing immunosuppression or have their dosages decreased in case of COVID-19 coinfection.

GABA(B) receptors function as a heteromeric assembly of the subunits GABA(B)R1 and GABA(B)R2

The principal inhibitory neurotransmitter GABA (gamma-aminobutyric acid) exerts its effects through two ligand-gated channels, GABA(A) and GABA(C) receptors, and a third receptor, GABA(B) , which acts through G proteins to regulate potassium and calcium channels. Cells heterologously expressing the cloned DNA encoding the GABA(B)R1 protein exhibit high-affinity antagonist-binding sites, but they produce little of the functional activity expected from studies of endogenous GABA(B) receptors in the brain. Here we describe a new member of the GABA(B) polypeptide family, GABA(B)R2, that shows sequence homology to GABA(B)R1. Neither GABA(B)R1 nor GABA(B)R2, when expressed individually, activates GIRK-type potassium channels; however, the combination of GABA(B)R1 and GABA(B)R2 confers robust stimulation of channel activity. Both genes are co-expressed in individual neurons, and both proteins co-localize in transfected cells. Moreover, immunoprecipitation experiments indicate that the two polypeptides associate with each other, probably as heterodimers. Several G-protein-coupled receptors (GPCRs) exist as high-molecular-weight species, consistent with the formation of dimers by these receptors, but the relevance of these species for the functioning of GPCRs has not been established. We have now shown that co-expression of two GPCR structures, GABA(B)R1 and GABA(B)R2, belonging to the same subfamily is essential for signal transduction by GABA(B) receptors.

p53 deficiency rescues the adverse effects of telomere loss and cooperates with telomere dysfunction to accelerate carcinogenesis

Maintenance of telomere length and function is critical for the efficient proliferation of eukaryotic cells. Here, we examine the interactions between telomere dysfunction and p53 in cells and organs of telomerase-deficient mice. Coincident with severe telomere shortening and associated genomic instability, p53 is activated, leading to growth arrest and/or apoptosis. Deletion of p53 significantly attenuated the adverse cellular and organismal effects of telomere dysfunction, but only during the earliest stages of genetic crisis. Correspondingly, the loss of telomere function and p53 deficiency cooperated to initiate the transformation process. Together, these studies establish a key role for p53 in the cellular response to telomere dysfunction in both normal and neoplastic cells, question the significance of crisis as a tumor suppressor mechanism, and identify a biologically relevant stage of advanced crisis, termed genetic catastrophe.

Essential role for oncogenic Ras in tumour maintenance

Advanced malignancy in tumours represents the phenotypic endpoint of successive genetic lesions that affect the function and regulation of oncogenes and tumour-suppressor genes. The established tumour is maintained through complex and poorly understood host-tumour interactions that guide processes such as angiogenesis and immune sequestration. The many different genetic alterations that accompany tumour genesis raise questions as to whether experimental cancer-promoting mutations remain relevant during tumour maintenance. Here we show that melanoma genesis and maintenance are strictly dependent upon expression of H-RasV12G in a doxycycline-inducible H-Ras12G mouse melanoma model null for the tumour suppressor INK4a. Withdrawal of doxycycline and H-RasV12G down-regulation resulted in clinical and histological regression of primary and explanted tumours. The initial stages of regression involved marked apoptosis in the tumour cells and host-derived endothelial cells. Although the regulation of vascular endothelial growth factor (VEGF) was found to be Ras-dependent in vitro, the failure of persistent endogenous and enforced VEGF expression to sustain tumour viability indicates that the tumour-maintaining actions of activated Ras extend beyond the regulation of VEGF expression in vivo. Our results provide genetic evidence that H-RasV12G is important in both the genesis and maintenance of solid tumours.

The BCL-6 proto-oncogene controls germinal-centre formation and Th2-type inflammation

Structural alterations of the promoter region of the BCL-6 proto-oncogene represent the most frequent genetic alteration associated with non-Hodgkin lymphoma, a malignancy often deriving from germinal-centre B cells. The BCL-6 gene encodes a zinc-finger transcriptional repressor normally expressed in both B cells and CD4+ T cells within germinal centres, but its precise function is unknown. We show that mice deficient in BCL-6 displayed normal B-cell, T-cell and lymphoid-organ development but have a selective defect in T-cell-dependent antibody responses. This defect included a complete lack of affinity maturation and was due to the inability of follicular B cells to proliferate and form germinal centres. In addition, BCL-6-deficient mice developed an inflammatory response in multiple organs characterized by infiltrations of eosinophils and IgE-bearing B lymphocytes typical of a Th2-mediated hyperimmune response. Thus, BCL-6 functions as a transcriptional switch that controls germinal centre formation and may also modulate specific T-cell-mediated responses. Altered expression of BCL-6 in lymphoma represents a deregulation of the pathway normally leading to B cell proliferation and germinal centre formation.

Timing of CNS cell generation: a programmed sequence of neuron and glial cell production from isolated murine cortical stem cells

Multipotent stem cells that generate both neurons and glia are widespread components of the early neuroepithelium. During CNS development, neurogenesis largely precedes gliogenesis: how is this timing achieved? Using clonal cell culture combined with long-term time-lapse video microscopy, we show that isolated stem cells from the embryonic mouse cerebral cortex exhibit a distinct order of cell-type production: neuroblasts first and glioblasts later. This is accompanied by changes in their capacity to make neurons versus glia and in their response to the mitogen EGF. Hence, multipotent stem cells alter their properties over time and undergo distinct phases of development that play a key role in scheduling production of diverse CNS cells.

Histological precursors of oesophageal squamous cell carcinoma: results from a 13 year prospective follow up study in a high risk population

BACKGROUND

Oesophageal squamous cell carcinoma (OSCC) has a very poor prognosis, which is largely due to late diagnosis. Successful early detection strategies will require identification of clinically relevant precursor lesions that can be targets for screening and treatment.

AIMS

To identify the clinically relevant histological precursors of OSCC.

SUBJECTS

A cohort of 682 endoscoped patients from a high risk rural population in Linxian, China.

METHODS

Subjects were endoscoped and biopsied at baseline and followed for 13.5 years. We estimated the relative risk of developing OSCC for each of the initial histological diagnoses using Cox proportional hazards regression models.

RESULTS

A total of 114 (16.7%) patients developed OSCC during the follow up period. After adjusting for potential confounding factors, relative risks (95% confidence intervals) for incidence of this tumour, by initial histological diagnosis, were: normal 1.0 (reference), oesophagitis 0.8 (0.2-3.2), basal cell hyperplasia 1.9 (0.8-4.5), mild dysplasia 2.9 (1.6-5.2), moderate dysplasia 9.8 (5.3-18.3), severe dysplasia 28.3 (15.3-52.3), and carcinoma in situ 34.4 (16.6-71.4).

CONCLUSIONS

In this study, squamous dysplasia and carcinoma in situ were the only histological lesions associated with a significantly increased risk of developing OSCC within 13.5 years after endoscopy. There was no evidence that oesophagitis predisposed to this tumour. Increasing grades of dysplasia were strongly associated with increasing risk, indicating that the histological grading was clinically meaningful. The follow up experience of severe dysplasia and carcinoma in situ was equivalent, suggesting that this distinction is not clinically relevant. Documenting these precursor lesions of OSCC should assist in the development of effective prevention, early detection, and treatment strategies for this disease.

Nutrition intervention trials in Linxian, China: multiple vitamin/mineral supplementation, cancer incidence, and disease-specific mortality among adults with esophageal dysplasia

BACKGROUND

A number of vitamins and minerals have been shown to influence carcinogenesis in experimental animals. In humans, epidemiologic evidence suggests that intake of fruits and vegetables may reduce risk of esophageal and other cancers. Vitamins and minerals in these foods may contribute to the reduced cancer risk. The people of Linxian, China, have persistently low intake of multiple nutrients and exhibit one of the world's highest rates of esophageal/gastric cardia cancer, with an exceptionally high risk of esophageal dysplasia.

PURPOSE

To determine whether supplementation with multiple vitamins and minerals may reduce esophageal/gastric cardia cancer among persons with esophageal dysplasia, we conducted a 6-year prospective intervention trial in Linxian.

METHODS

Mortality and cancer incidence were ascertained from May 1985 through May 1991 for 3318 persons with cytologic evidence of esophageal dysplasia who were randomly assigned to receive, throughout that period, daily supplementation with 14 vitamins and 12 minerals or placebo. Doses were typically two to three times U.S. Recommended Daily Allowances. Compliance was assessed by counting unused pills monthly for all trial participants and by assaying nutrient levels in blood collected from samples of individuals randomly selected without replacement every 3 months throughout the trial. Cancers were identified through routine surveillance and by special cytology and endoscopy screenings after 2 1/2 years and 6 years.

RESULTS

A total of 324 deaths occurred during the 6-year intervention period; 167 occurred in the control (placebo) group and 157 occurred in the supplement group. Cancer was the leading cause of death (54% of all deaths); 18% were due to cerebrovascular diseases and 29% to other causes. Cumulative esophageal/gastric cardia death rates were 8% lower (relative risk [RR] = 0.92; 95% confidence interval [CI] = 0.67-1.28) among individuals receiving supplements rather than placebo, a nonsignificant (P > .10) difference. Risk of total mortality was 7% lower (RR = 0.93; 95% CI = 0.75-1.16; P > .10), total cancer 4% lower (RR = 0.96; 95% CI = 0.71-1.29; P > .10), cerebrovascular disease 38% lower (RR = 0.62; 95% CI = 0.37-1.06; P = .08), and other diseases 12% higher (RR = 1.12; 95% CI = 0.74-1.69; P > .10) among the treated group. Cumulative cancer incidence rates were nearly the same in the two groups.

CONCLUSIONS

No substantial short-term beneficial effect on incidence or mortality for this type of cancer occurred following daily supplementation with multiple vitamins and minerals among adults with precancerous lesions of the esophagus.

IMPLICATIONS

Although no statistically significant short-term benefits were observed, longer follow-up should be more informative about the effectiveness of this 6-year supplementation on cancer and other diseases among individuals with esophageal dysplasia.

Functional dissection of an abscisic acid (ABA)-inducible gene reveals two independent ABA-responsive complexes each containing a G-box and a novel cis-acting element

To elucidate the mechanism by which abscisic acid (ABA) regulates gene expression, the promoter of the barley ABA-responsive HVA22 gene has been analyzed by both loss- and gain-of-function studies. Previous reports indicate that G-box sequences, which are present in genes responding to a variety of environmental and physiological cues, are involved in ABA response. However, our data suggest that G-box sequences are necessary but not sufficient for ABA response. Instead, an ABA response complex consisting of a G-box, namely, ABRE3 (GCCACGTACA), and a novel coupling element, CE1 (TGCCACCGG), is sufficient for high-level ABA induction, and replacement of either of these sequences abolishes ABA responsiveness. We suggest that the interaction between G-box sequences, such as ABRE3 in the HVA22 gene, and CE-type sequences determines the specificity in ABA-regulated gene expression. Our results also demonstrate that the ABA response complex is the minimal promoter unit governing high-level ABA induction; four copies of this 49-bp-long complex linked to a minimal promoter can confer more than 100-fold ABA-induced gene expression. In addition to ABA response complex 1, composed of ABRE3 and CE1, the HVA22 promoter contains another ABA response complex. The ABA responsiveness of this ABA response complex 2 relies on the interaction of G-box (ABRE2; CGCACGTGTC) with another yet unidentified coupling element. These two complexes contribute incrementally to the expression level of HVA22 in response to ABA.

Retinoid X receptors: X-ploring their (patho)physiological functions

Retinoid X receptor (RXR) belongs to a family of ligand-activated transcription factors that regulate many aspects of metazoan life. A class of nuclear receptors requires RXR as heterodimerization partner for their function. This places RXR in the crossroad of multiple distinct biological pathways. This and the fact that the debate on the endogenous ligand requirement for RXR is not yet settled make RXR still an enigmatic transcription factor. Here, we review some of the biology of RXR. We place RXR into the evolution of nuclear receptors, review structural details and ligands of the receptor. Then processes regulated by RXR are discussed focusing on the developmental roles deduced from studies on knockout animals and metabolic roles in diseases such as diabetes and atherosclerosis deduced from pharmacological studies. Finally, aspects of RXR's involvement in myeloid differentiation and apoptosis are summarized along with issues on RXR's suitability as a therapeutic target.

Modular nature of abscisic acid (ABA) response complexes: composite promoter units that are necessary and sufficient for ABA induction of gene expression in barley

The modular nature of the abscisic acid response complex (ABRC), the promoter unit necessary and sufficient for abscisic acid (ABA) induction of gene expression in barley, is defined in this study. We investigated ABA induction of a barley late embrogenesis abundant (Lea) gene, HVA1, and found that the ABRC of this gene consists of a 10-bp box with an ACGT core (ACGT-box) and the 11 bp directly upstream, named coupling element 3 (CE3). Only one copy of this ABRC is sufficient to confer ABA induction when linked to a minimal promoter. Because we previously reported another ABRC in the barley HVA22 gene, which consists of an ACGT-box with a distal coupling element (CE1), exchange experiments were conducted to study the interaction among modular elements in these ABRCs. We show that ACGT-boxes in these ABRCs are interchangeable, indicating that an ACGT-box can interact with either a distal or a proximal coupling element to confer ABA response. However, the two coupling elements are not fully exchangeable. Although CE3 can function either proximal or distal to the ACGT-box, CE1 is only functional at the distal position. The presence of both the distal and the proximal coupling elements has a synergistic effect on the absolute level of expression as well as on ABA induction. These ABRCs function in both seed and vegetative tissues. In seeds, ABA induction of the ABRC containing the proximal CE3, but not the ABRC with the distal CE1, is enhanced in the presence of the transcription regulator Viviparous1, indicating that these two ABRCs are mediated by different ABA signal transduction pathways.

Medial temporal lobe atrophy on MRI scans and the diagnosis of Alzheimer disease

BACKGROUND

Despite convenience, accessibility, and strong correlation to severity of Alzheimer disease (AD) pathology, medial temporal lobe atrophy (MTA) has not been used as a criterion in the diagnosis of prodromal and probable AD.

METHODS

Using a newly validated visual rating system, mean MTA scores of three bilateral medial temporal lobe structures were compared for subjects with no cognitive impairment (NCI) (n = 117), nonamnestic mild cognitive impairment (MCI) (n = 46), amnestic MCI (n = 45), and probable AD (n = 53). Correlations between MTA scores and neuropsychological test scores at baseline, and predictors of change in diagnosis at 1-year follow-up were evaluated.

RESULTS

With NCI as the reference group, a mean MTA cut score of 1.33 yielded an optimal sensitivity/specificity of 85%/82% for probable AD subjects and 80%/82% for amnestic MCI subjects. MTA and Clinical Dementia Rating Sum of Boxes scores at baseline were independent and additive predictors of diagnosis at baseline, and of transition from NCI to MCI or from MCI to dementia at 1-year follow-up.

CONCLUSION

Medial temporal lobe atrophy (MTA) scores 1) distinguish probable Alzheimer disease (AD) and amnestic mild cognitive impairment (MCI) subjects from nonamnestic MCI and no cognitive impairment (NCI) subjects, 2) help predict diagnosis at baseline, and 3) predict transition from NCI to MCI and from MCI to probable AD. MTA scores should be used as a criterion in the clinical diagnosis of AD.

Intrinsic programs of patterned cell lineages in isolated vertebrate CNS ventricular zone cells

Using long-term, time-lapse video-microscopy, we investigated how single progenitor cells isolated from the early embryonic cerebral cortex produce neurons and glia over time. Clones of 10 cells or less were produced by short symmetric or asymmetric division patterns, commonly terminating in a ‘pair progenitor’ for two morphologically identical neurons. Larger trees were composites of these short sub-lineages: more prolific neuroblasts underwent repeated asymmetric divisions, each producing a minor neuroblast that typically made (3/4)10 progeny, and a sister cell capable of generating more progeny. Particular division patterns were seen repeatedly. In contrast, glioblasts underwent a prolonged series of symmetric divisions. These patterned lineage trees were generated from isolated cells growing on plastic, suggesting they are largely intrinsically programmed. Our data demonstrate for the first time that CNS progenitor cells have stereotyped division patterns, and suggest that as in invertebrates, these may play a role in neural development.

An abscisic acid-induced protein kinase, PKABA1, mediates abscisic acid-suppressed gene expression in barley aleurone layers

The phytohormone abscisic acid (ABA) induces genes-encoding proteins involved in desiccation tolerance and dormancy in seeds, but ABA also suppresses gibberellin (GA)-responsive genes encoding hydrolytic enzymes essential for postgermination growth. A unique serine/threonine protein kinase, PKABA1 mRNA, up-regulated by ABA in seeds, has been identified. In this report, the effect of PKABA1 on the signal transduction pathway mediating ABA induction and suppression of genes has been determined in aleurone layers of barley seeds. Two groups of gene constructs were introduced to barley aleurone layers by using particle bombardment: the reporter constructs containing the coding sequence of beta-glucuronidase gene linked to hormone-responsive promoters and the effector constructs containing the coding region of protein kinases linked to a constitutive promoter. Constitutive expression of PKABA1 drastically suppressed expression of low- and high-pI alpha-amylase and protease genes induced by GA. However, the presence of PKABA1 had only a small effect on the ABA induction of a gene encoding a late embryogenesis abundant protein, HVA1. Our results indicate that PKABA1 acts as a key intermediate in the signal transduction pathway leading to the suppression of GA-inducible gene expression in cereal aleurone layers.

A promoter recruitment mechanism for tumor necrosis factor-alpha-induced interleukin-8 transcription in type II pulmonary epithelial cells. Dependence on nuclear abundance of Rel A, NF-kappaB1, and c-Rel transcription factors

The alveolar macrophage-derived peptide tumor necrosis factor-alpha (TNFalpha) initiates pulmonary inflammation through its ability to stimulate interleukin-8 (IL-8) synthesis in alveolar epithelial cells through an incompletely described transcriptional mechanism. In this study, we use the technique of ligation-mediated polymerase chain reaction (LMPCR) to record changes in transcription factor occupancy of the IL-8 promoter after TNFalpha stimulation of A549 human alveolar cells. Using dimethylsulfate/LMPCR, no detectable proteins bind the TATA box in unstimulated cells. By contrast, TNFalpha rapidly induces protection of G residues at -79 and -80 coincident with endogenous IL-8 gene transcription. Using DNase I/LMPCR, we observe inducible protection of nucleotides -60 to -99 (the TNF response element) and nucleotides -3 to -32 (containing the TATA box). Surprisingly, extensive TATA box protection is only seen after TNFalpha stimulation. Using a two-step microaffinity isolation/Western immunoblot DNA binding assay, we observe that the NF-kappaB subunits Rel A, NF-kappaB1, and c-Rel inducibly bind the TNF response element; these proteins undergo rapid TNFalpha-inducible increases in nuclear abundance as a consequence of IkappaBalpha proteolysis. Furthermore, the peptide aldehyde N-acetyl-Leu-Leu-norleucinal, an agent that blocks both IkappaBalpha proteolysis and NF-kappaB subunit translocation, abrogates recombinant human TNFalpha-inducible IL-8 gene transcription. These studies demonstrate that IL-8 is activated by a promoter recruitment mechanism in alveolar epithelial cells, where NF-kappaB subunit translocation is required for (and coincident with) binding of the constitutively active TATA box-binding proteins.

MicroRNA-29c functions as a tumor suppressor by direct targeting oncogenic SIRT1 in hepatocellular carcinoma

Mammalian sirtuin 1 (SIRT1) has connected to an ever widening circle of activities that encompass cellular stress resistance, energy metabolism and tumorigenesis. However, underlying mechanisms leading to oncogenic SIRT1 overexpression are less understood. In this study, we identified SIRT1 regulatory microRNA (miRNA) and its function in hepatocellular carcinoma (HCC). Aberrant SIRT1 overexpression was demonstrated in a subset of human HCCs. SIRT1 knockdown suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins. This led to hypophosphorylation of pRb, which inactivated E2F/DP1 target gene transcription, and thereby caused significant increase of HCC cells to remain in the G1/S phase. A comprehensive miRNA profiling analysis indentified five putative endogenous miRNAs that are significantly downregulated in HCC. Ectopic expression of miRNA mimics evidenced miR-29c to suppress SIRT1 in HCC cells. Notably, ectopic miR-29c expression repressed cancer cell growth and proliferation, and it recapitulated SIRT1 knockdown effects in HCC cells. In addition, miR-29c expression was downregulated in a large cohort of HCC patients, and low expression of miR-29c was significantly associated with poor prognosis of HCC patients. Taken together, we demonstrated that miR-29c suppresses oncogenic SIRT1 by way of binding to 3'-untranslated region of SIRT1 mRNA causing translational inhibition in liver cancer cells. The loss or suppression of miR-29c may cause aberrant SIRT1 overexpression and promotes liver tumorigenesis. Overall, we suggest that miR-29c functions as a tumor suppressor by regulating abnormal SIRT1 activity in liver.

Factors that predict the referral of breast cancer patients onto clinical trials by their surgeons and medical oncologists

PURPOSE

To improve understanding of physicians' reluctance to refer patients to clinical trials.

METHODS

This study was conducted in a large metropolitan region from 1993 to 1995 using a two-staged population-based sampling strategy. A total of 147 physicians discussed 245 patient cases and their own knowledge, attitudes, and practices toward clinical trials.

RESULTS

Ninety-three patients (38. 0%) were offered a trial, and 49 (52.7%) of them agreed to participate. Forty-five patients (18.4%) actually received their adjuvant therapy on trial. Older patients and those with a poorer prognosis were less likely to be referred. Patients who delayed their decision were more than three times as likely to participate in a trial and more than eight times as likely to participate when they were reported to be actively involved in making the decision. Generally, physicians in university settings and who had formal support from a cooperative group were more likely to refer patients to trials. More specifically, surgeons referred more patients to trials when they felt comfortable explaining trials or believed that treatment should not stray from protocol. Oncologists were less likely to make referrals if they perceived the paperwork to be onerous or entry requirements to be too stringent. Surgeons' participation in recommending adjuvant therapy to patients resulted in more trial referrals unless they treated their patients with tamoxifen.

CONCLUSION

(1) Physicians still need to overcome attitudinal and practical barriers to trial participation, (2) more support for physicians is needed, (3) surgeons may play a pivotal role in the recruitment of patients to adjuvant therapy trials, and (4) garnering patient enthusiasm for trial participation and involving them in the choice of adjuvant therapy may be key components to increasing trial enrollment.

Hypertrophic scar tissues and fibroblasts produce more transforming growth factor-beta1 mRNA and protein than normal skin and cells

Transforming growth factor-beta1 is a well-known fibrogenic cytokine produced by many types of cells including dermal fibroblasts. To investigate whether this fibrogenic cytokine is involved in development of hypertrophic scar, transforming growth factor-beta1 gene expression was evaluated in small skin samples. Because a sufficient quantity of normal skin from patients with hypertrophic scar is not readily available, a reverse transcription-polymerase chain reaction technique was used. Quantitation of gene expression by reverse transcription-polymerase chain reaction is difficult partly due to the lack of suitable complementary RNA standards. We have established a convenient, reliable procedure to construct an internal standard for transforming growth factor-beta1 starting with a gene specific polymerase chain reaction product. After digestion of the polymerase chain reaction product with endonuclease, a small piece of cDNA from human procollagen alpha1(I) cDNA with compatible ends was inserted into the polymerase chain reaction-DNA fragment. The recombinant cDNA was re-amplified by polymerase chain reaction and subcloned into a plasmid containing bacteriophage T7 and T3 promoters. Complementary RNA was prepared from the recombinant plasmid and amplified by reverse transcription-polymerase chain reaction together with the tissue or cellular RNA. After amplification, the products were electrophoresed in an agarose gel containing ethidium bromide. The bands for internal standard and transforming growth factor-beta1 mRNA were scanned, digitized, and plotted against the amount of internal standard complementary RNA added in the reverse transcription-polymerase chain reaction. The number of mRNA molecules/cell was calculated. We examined the transforming growth factor-beta1 mRNA in hypertrophic scar tissue and in normal skin and found that hypertrophic scar tissues expressed five-fold more transforming growth factor-beta1 mRNA than normal skin per unit of wet weight. We used this procedure to quantitate transforming growth factor-beta1 mRNA expression in 5 pairs of fibroblast cultures derived from hypertrophic scar and normal skin. The results showed that hypertrophic scar fibroblast cultures contain significantly more molecules of mRNA for transforming growth factor-beta1 than normal cells (116 +/- 6 vs. 97 +/- 7, p = 0.017, n = 5). These results were supported by Northern analysis for transforming growth factor-beta1 mRNA in the cells and enzyme-linked immunosorbent assay for TGF-beta1 protein in fibroblast-conditioned medium. In conclusion, hypertrophic scar tissue and fibroblasts produce more mRNA and protein for transforming growth factor-beta1, which may be important in hypertrophic scar formation. The construction of the gene specific internal standard for reverse transcription-polymerase chain reaction is a simple and reliable procedure useful to quantitate gene expression in a small amount of tissue or number of cells.

Hepatitis E virus infection among domestic animals in eastern China

Hepatitis E virus (HEV) is a zoonotic pathogen of which several species of animal were reported as reservoirs. Antibodies to HEV and HEV RNA have been detected in some Chinese population and swine groups but few other domestic animals. In this study, to investigate the HEV prevalence, we tested sera from 788 pigs, 100 cows, 50 goats, 49 horses, 101 pet dogs, 105 chickens, 47 duck and 45 pigeons in eastern China for anti-HEV immunoglobulin G (IgG). We also tested 50% of the swine sera, all of sera from the other domestic animals and 13 Shanghai human sera which were positive for anti-HEV immunoglobulin M (IgM) for HEV RNA using reverse transcriptase-polymerase chain reaction. Our results indicated that 82.5% (222/269) of the sows, 53.9% (104/193) of the 4- to 6-month-old swine, 63.4% (168/265) of the 1- to 3-month-old swine, 55.7% (34/61) of the slaughterhouse swine, 24% (12/50) of the goats, 16.3% (8/49) of the horses, 17.8% (21/101) of the pet dogs, 6% (6/100) of the cows, 12.8% (6/47) of the ducks, 4.4% (2/45) of the pigeons and 1.9% (2/105) of the chickens exhibited positive for anti-HEV IgG. Inhibition assay confirmed the infection with HEV or HEV-like viruses in these domestic animals except pigeons and chickens. From the sera, we isolated 18 swine HEV strains, one horse HEV strain and two human HEV strains. Sequence analysis showed that the horse HEV isolate and one swine isolate belonged to genotype 3. The other isolates belonged to genotype 4. The two human isolates were phylogenetically closely related to eight of the swine isolates. In short, the presence of anti-HEV antibody had been confirmed in several species of domestic animals in eastern China and HEV RNA has been identified in swine, human and horse. This suggested that the authorities should pay more attention to the prevalence of HEV in eastern China.

Human papillomavirus (HPV) DNA in esophageal precancer lesions and squamous cell carcinomas from China

A series of 51 biopsies derived from the same number of patients with established invasive squamous-cell carcinoma of the esophagus in Linxian, a high-risk area for esophageal cancer in China, were analyzed histologically and by in situ DNA hybridization to demonstrate human papillomavirus (HPV) infection. Epithelial changes suggesting HPV infection within or adjacent to the carcinoma lesions were found in 25 cases (49.0%). Esophageal lesions with HPV morphology showed both flat (25 cases) and inverted condylomas (2 cases) resembling those found in the genital tract. HPV 6, 11, 16 or 18 DNA sequences were detected in 22/51 (43.1%) of the esophageal specimens. HPV DNA was most frequently localized in epithelium adjacent to carcinomas in areas showing either epithelial hyperplasia (36.1%) or dysplasia (22.2%). Of the lesions with morphological HPV changes, 64% (16/22) were shown to contain HPV DNA. In 2 specimens, HPV DNA was found in frankly malignant cells. High-risk types HPV 16 and/or 18 DNA sequences were found in 16 of the 22 HPV DNA-positive cases (72.7%). Our results confirm previously reported HPV involvement in esophageal squamous-cell lesions, and support the hypothesis of HPV as a possible etiological agent in esophageal carcinogenesis.

The AP-1 transcription factor regulates breast cancer cell growth via cyclins and E2F factors

The activating protein-1 (AP-1) transcription factor transduces growth signals through signal transduction pathways to the nucleus, leading to the expression of genes involved in growth and malignant transformation in many cell types. We have previously shown that overexpression of a dominant negative form of the cJun proto-oncogene, a cJun dominant negative mutant (Tam67), blocks AP-1 transcriptional activity, induces a G(1) cell cycle block and inhibits breast cancer cell growth in vitro and in vivo. We found that AP-1 blockade by Tam67 in MCF-7 breast cancer cells downregulates cyclin D1 transcriptional activity by at least two mechanisms: by suppressing transcription at the known AP-1 binding site (-934/-928) and by suppressing growth factor-induced expression through suppressing E2F activation at the E2F-responsive site (-726/-719). AP-1 blockade also led to reduced expression of E2F1 and E2F2, but not E2F4, at the mRNA and protein levels. Chromatin immunoprecipitation and supershift assays demonstrated that AP-1 blockade caused decreased binding of E2F1 protein to the E2F site in the cyclin D1 promoter. We also found that Tam67 suppressed the expression of the E2F1 dimerizing partner, DP1 and E2F-upregulated cell cycle genes (cyclins E, A, B and D3) and enhanced the expression of E2F-downregulated cell cycle genes (cyclins G(2) and I). Reduced expression of other E2F-regulated genes was also seen with AP-1 blockade and E2F suppression. Thus, the AP-1 factor regulates the expression of cyclin D and E2F (the latter in turn regulates E2F-downstream genes), leading to cell cycle progression and breast cancer cell proliferation.

Effect of ammonium and nitrate nutrition on some physiological processes in higher plants - growth, photosynthesis, photorespiration, and water relations

Ammonium and nitrate as different forms of nitrogen nutrients impact differently on some physiological and biochemical processes in higher plants. Compared to nitrate, ammonium results in small root and small leaf area, which may contribute to a low carbon gain, and an inhibition on growth. On the other hand, due to (photo)energy saving, a higher CO (2) assimilation rate per leaf area was observed frequently in plants supplied with ammonium than in those supplied with nitrate. These results were dependent not only on higher Rubisco content and/or activity, but also on RuBP regeneration rate. The difference in morphology such as chloroplast volume and specific leaf weight might be the reason why the CO (2) concentration in the carboxylation site and hence the photorespiration rate differs in plants supplied with the two nitrogen forms. The effect of nitrogen form on water uptake and transportation in plants is dependent both on leaf area or shoot parameter, and on the root activity (i.e., root hydraulic conductivity, aquaporin activity).

Functional nicotinic acetylcholine receptor expression in stem and progenitor cells of the early embryonic mouse cerebral cortex

The adult cerebral cortex contains nicotinic acetylcholine (ACh) receptors vital to cortical function. However, little is known about the assembly of embryonic nicotinic receptor subunits into functional receptors or whether they play an active role in cortical development. We now report evidence of functional nicotinic acetylcholine receptor channels in fetal mouse cerebral cortex as early as embryonic day 10 (E10), when the cortex consists of dividing stem and progenitor cells. Patch-clamp electrophysiological measurements indicate that nicotine and ACh evoke sizable inward currents characteristic of nicotinic receptors, that are strongly rectifying with a reversal potential near 0 mV. Three different nicotinic agonists, ACh, nicotine, and dimethylphenylpiperazinium, evoked cytosolic Ca(2+) signals. Agonist-evoked Ca(2+) signals and electrophysiological responses were found in greater than 70% of all E10-E11 cells tested and were blocked by nicotinic receptor antagonists. The Ca(2+) response to nicotinic agonists was markedly prolonged in cells from early embryonic stages relative to later stages of development. alpha3, alpha4, and alpha7 receptor subunit proteins were detected immunocytochemically in cortical cells from E10 to birth. The incidence of each subunit declined with embryonic age, suggesting a role in early development. We discuss the possible function of nicotinic receptors in early cortical development and their role as a target for nicotine in the developmental pathologies associated with the fetal tobacco syndrome.