Characterization of the human p57KIP2 gene: alternative splicing, insertion/deletion polymorphisms in VNTR sequences in the coding region, and mutational analysis

We have isolated human cDNA and genomic clones of a gene termed p57KIP2, which is related to the p2I WAFI and p27 KIP1 genes that encode inducible inhibitors of cyclin-dependent kinase activity. The p57 gene contains three GC-rich introns of 166 bp, 566 bp, and 83 bp, and two of the four exons correspond to coding regions. Alternative splicing generates the heterogeneity in the translational initiations. As this gene has been localized to chromosomal band 11pI5.5, a region thought to be the location of a tumor suppressor gene(s) for carcinomas of the breast, bladder, and liver, we have examined a large number of tumors for genetic alterations of p57. Although no somatic mutation has been detected, we have found several normal variations in this gene, including four types of 12-bp in-frame deletions in the proline/alanine repeating domain, in which nearly 40 motifs, viz., 5'-CCGGCC-3', are tandemly repeated.

Immunohistochemical detection of p53 tumor suppressor protein in porokeratosis

We examined 9 Japanese cases of porokeratosis (4 of the plaque type, 2 of disseminated superficial actinic porokeratosis, 2 of disseminated superficial porokeratosis, and one of giant porokeratosis) for the expression of p53 tumor suppressor protein immunohistochemically, using two anti-p53 antibodies, CM1 and DO1. The same results were obtained with both antibodies. The epidermis central to the cornoid lamellae was positive in 8 of 9 specimens. On the other hand, the peripheral epidermis was positive in 2 of the 9 cases. The epidermis beneath the cornoid lamellae was positive in 3 of the 9 cases. The frequency of p53 positivity was significantly higher in the epidermis central to cornoid lamellae over that beneath or peripheral to them (Fisher's exact probability test, p < 0.05). The majority of squamous cell carcinoma cells arising on giant porokeratosis stained with CM1 and DO1. These data may suggest that the abnormal p53 expression has some relevance to the skin carcinogenesis of porokeratosis.

Cisplatin microcrystals suspended in oil: pathological study of acute toxicity in mice

The pathological changes brought about by the i.p. administration of a new dosage format, cisplatin microcrystals suspended in oil (CDDP-Oil), was examined in mice. CDDP-Oil decreased the absolute weight and the relative weight (organ weight/body weight) of the kidney, liver and spleen in the mice receiving the dosage form. However, the severity of the reduction of the organ weight in the CDDP-Oil administration groups was not different from that in the cisplatin aqueous solution (CDDP-Sol) administration groups. Histologically, severe degeneration and atrophy were recognized in the kidney, large intestine, small intestine, thymus, spleen, bone marrow and lymph nodes in the CDDP-Oil administration groups as well as CDDP-Sol administration groups. However, there were no additional changes in the macroscopic and microscopic findings in the CDDP-Oil groups. From these results, we concluded that this dosage form did not change the toxicity of cisplatin in terms of pathological effects.

Identification of a new outwardly rectifying Cl- channel that belongs to a subfamily of the ClC Cl- channels

A new outwardly rectifying Cl- channels (ORCC) that belongs to ClC Cl- channel family has been identified from rat kidney and designated as ClC-5. ClC-5 cDNA encodes a polypeptide of 746 amino acids, which is indicated by hydrophobicity analysis to have structural features that are common of the ClC family. However, the amino acid sequence was weakly homologous to those of other ClC Cl- channels except for ClC-3, which we recently identified as a Ca2+-sensitive ORCC. Northern blot analysis of rat tissues showed that ClC-5 mRNA was predominantly expressed in the kidney and colon. To characterize the functional properties of ClC-5 by whole cell patch-clamp technique, we established the stably transfected CHO-K1 cell line using intranuclear microinjection technique. The transfected cells induced outwardly rectifying and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-sensitive Cl- currents on whole cell configuration. Following the identification of two highly homologous ORCCs, ClC-3 and ClC-5, a new subfamily encoding ORCC has emerged in the ClC family. Furthermore, ClC-5 was almost identical to a partial sequence of human cDNA that is related to Dent's disease. The molecular structure and functional properties of ClC-5 will provide an important insight into ORCCs and the pathogenesis of Dent's disease.

Molecular cloning and tissue distribution of rat peptide transporter PEPT2

A cDNA encoding rat H(+)- coupled peptide transporter PEPT2 was isolated. The cDNA encoded a protein of 729 amino acids with 48% amino acid identity to the rat PEPT1. The mRNA expression of rat PEPT2 was predominant in the kidney. When expressed in Xenopus oocytes, rat PEPT2 stimulated the uptake of bestatin, a dipeptide-like drug.

Endogenous interleukin-4, but not interleukin-10, is involved in suppression of host resistance against Listeria monocytogenes infection in interferon-depleted mice

The production and roles of endogenous interleukin-4 (IL-4) and IL-10 in a sublethal infection with Listeria monocytogenes were studies in normal mice and anti-gamma interferon (IFN-gamma) monoclonal antibody (MAb)-pretreated mice. In normal mice, the expression of mRNAs for IL-4 and IL-10, which was amplified by reverse transcription-PCR, was induced in the spleens and livers either early or late in infection, although the serum IL-4 and IL-10 were not detectable by enzyme-linked immunosorbent assays. In vivo administration of anti-IL-4 MAb showed no effect on antilisterial resistance, whereas anti-IL-10 MAb partially diminished the defense. In anti-IFN-gamma MAb-pretreated mice, a delay in the bacterial elimination from the spleens and livers was observed and high titers of serum IL-4 and IL-10 were induced late in infection. Production of endogenous IL-4 and IL-10 was suppressed in both CD4+ cell-and CD8+ cell depleted mice. The suppression of antilisterial resistance in anti-IFN-gamma MAb-pretreated mice was canceled when anti-IL-4 MAb was injected late in infection, whereas anti-IL-10 MAb showed no effect. These results suggest that the host immune responses were polarized into the T-helper 2 phenotype in anti-IFN-gamma MAb-pretreated mice and that inhibition of host resistance against L. monocytogenes by depletion of IFN-gamma might be attributable to IL-4 produced by T cells polarized into the T-helper 2 phenotype as well as the inhibition of the IFN-gamma effects.

[Mutation of the mismatch repair genes for carcinogenesis of sporadic colorectal cancers with RER-positive phenotype]

Genetic instability, monitored by (a) replication error, is a feature of many hereditary and sporadic colorectal cancers. When such tumors are familial, the genetic instability is thought to be triggered by inherited mutations in DNA-mismatch repair genes but the mechanism by which sporadic tumors exhibit RER+ phenotypes is not as well understood. We examined RER in 129 sporadic colorectal tumors. In eight of them that exhibited RER+ at two or more loci, we screened for mutations of hMLH1 and hMSH2. We detected only two mutations; one was a constitutional mutation of hMLH1 and the other was a somatic mutation of hMSH2. These results suggest that RER in sporadic tumors does not always reflect germline mutation in genes associated with mismatch repair.

[Molecular biology of transporters in GI tracts]

The transporters and channels expressed in gastrointestinal tracts were reviewed. The transporters at the apical membrane are coupled with sodium, chloride or hydrogen ions and elecrogenic to accumulate substrates actively against concentration gradient. The transporters at the basolateral membrane are usually facilitators. They belong to several membrane protein families. Their members are increasing with homology cloning. The new families are found with expression cloning and genome sequencing. The posttranscriptional modulation and accesory proteins may regulate the activity of transporters. The mechanisms of tissue specific expression and gene expression are actively investigated.

A human/mouse chimeric monoclonal antibody against intercellular adhesion molecule-1 for tumor radioimmunoimaging

A mouse-human chimeric antibody for intercellular adhesion molecule-1 (ICAM-1) was established by using heavy chain loss mouse mutant hybridoma and human immunoglobulin expression vector. The HA58 hybridoma secreted anti-ICAM-1 monoclonal antibody (MoAb) (IgG1, kappa). The gene of the mouse variable region of heavy chain was amplified and cloned by the polymerase chain reaction technique directly from the HA58 hybridoma RNA. The variable region of heavy chain was joined with an expression vector which contains human gamma 1 constant gene. The expression vector was transfected into heavy chain loss mutant cells HA58-7, which produced only murine immunoglobulin light chains. The resultant chimeric MoAb HA58, chHA58, retained full-binding reactivity to ICAM-1 compared with murine HA58 parental antibody. The chimeric MoAb chHA58 showed little antibody dependent cell-mediated cytotoxic activity against cultured tumor cells. Biodistribution studies with 99mTc-labeled chHA58 in nude mice bearing human gastric carcinoma JRST cells demonstrated that the tumor-blood ratio was 1.55 at 18 h after injection, when the tumors were clearly visible in gamma scintigraphy. These data suggest that chHA58 may be of practical use for radioimmunoimaging of a wide variety of tumors.

Synaptic loss in anterior horn neurons in lower motor neuron disease

This report concerns an ultrastructural investigation of the synapses of anterior horn neurons in the lumbar spinal cord of four patients with lower motor neuron disease (LMND) who had no upper motor neuron and corticospinal tract involvement. Anterior horn neurons of five normal individuals served as controls. The cell body area and the number of synapses of the normal-appearing neurons of the LMND patients were significantly reduced (P < 0.0001). These findings suggest that synaptic changes of anterior horn neurons could be ascribed to the degeneration of lower motor neurons rather than to the influence of upper motor neuron system degeneration. On the other hand, the lengths of individual synapses (P < 0.0001) and of their active zones (P < 0.05) were significantly increased in the patients. These increases would indicate that synapses on anterior horn neurons of individuals with LMND appear to have the capacity to react to progressive degeneration and loss of other synapses by means of a compensatory response or plasticity that enhances their efficiency.

Structure of aquaporin-2 vasopressin water channel

Aquaporin-2 (AQP-2) is a vasopressin-regulated water channel in the kidney collecting duct. AQP-2 is selectively permeable to water molecule and is translocated between the apical membrane and subapical endosomes in response to vasopressin. To investigate the localization and structure of the aqueous pathway of the AQP-2 water channel, a series of site-directed mutants was constructed and functionally analyzed. Insertion of N-glycosylation reporter sequence into each hydrophilic loop (HL) indicated that AQP-2 has a six-membrane spanning topology and that insertional mutations in HL-2 or HL-5 do not alter water channel function. Mercury-sensitive site of AQP-2 is located near the second asparagine-proline-alanine (NPA) domain at cysteine 181, but not near the first NPA domain. Replacement of HL-3 or HL-4 with the corresponding part of Escherichia coli glycerol facilitator abolished water channel function without changing plasma membrane expression of the channel protein. Introduction of cysteine residues in His-122, Asn-123, Gly-154, Asp-155, or Asn-156 induced partial mercury sensitivity, and point mutations in asparagine 123 significantly altered water permeability. Our results implicate that the structure of AQP-2 is different from models previously proposed for AQP-1 and that HL-3 and HL-4 are closely located to the aqueous pathway.

Complete avulsion of the hamstring tendons from the ischial tuberosity. A report of two cases sustained in judo

Rupture of the hamstring tendon is a rare injury. Two cases of complete rupture of the hamstring tendons sustained while playing judo are reported. The diagnosis of a rupture of the hamstring tendons was difficult from physical examination because of severe pain on knee or hip joint movement. Magnetic resonance imaging was non-invasive and showed the lesion clearly. In one of these two cases the less satisfactory results of non-operative treatment were clearly shown in both isokinetic muscle force evaluation and sports activities.

[Hypoplastic mixed lineage leukemia successfully treated with low-dose cytosine arabinoside]

A 54-year-old male was admitted because of dyspnea on exercise. His peripheral blood revealed pancytopenia with severely hypoplastic bone marrow. Bone marrow aspiration showed a marked hypocellular marrow with 62.4% of blast cells. Cytochemical studies showed that peroxidase activity, alpha-nephtyl buthylate esterase activity and PAS reaction were negative, and that only ASD-chroloacetate esterase activity was positive. Surface marker analysis of blast cells showed positive result for CD5, 7, 33 and 34 antigens. The T-cell receptor beta gene was rearranged, but the immunoglobulin H chain gene showed a germ line configuration. Terminal Deoxynucleotydyl Transferase (TdT) was positive, but cellular surface and cytoplasmic immunoglobulin were not recognized. A diagnosis of hypoplastic mixed lineage leukemia was made and treated with low dose cytosine arabinoside, he resulted in complete remission. The relation between hypoplastic leukemia, AML-M0 and mixed lineage leukemia was also discussed.

[Liddle syndrome]

In 1963 Liddle et al. described a disorder that simulated primary aldosteronism, characterized by severe hypertension and hypokalemia but with negligible secretion of aldosterone. They theoried that this was a disorder in which the renal tubules transport ions with such abnormal facility that the end result simulates that of a mineralcorticoid excess. Later, it was postulated that this disorder could be related to the abnormality of amiloride sensitive Na channel. The activity of amiloride-sensitive Na channels constitutes the rate limiting step for Na reabsorption in Na transporting epithelia. Recently, the primary sequence of the rat amiloride-sensitive epithelial Na+ channel (rENaC) was determined by functional expression cloning and shown to be composed of three homologous subunits: alpha, beta, and gamma. Its expression of all three subunits in Xenopus oocytes markedly increased the magnitude of these currents. Analysis of subjects with Liddle's syndrome demonstrates the mutation of carboxy-terminal domain in alpha, beta, and gamma subunits. The mutations are either premature termination, frameshift mutation, or missense mutations.

Progressive dysphagia due to adult Chiari I malformation mimicking amyotrophic lateral sclerosis

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Ultrastructural study of synapses in the anterior horn neurons of patients with amyotrophic lateral sclerosis

This report concerns an ultrastructural examination of the synapses present on the surface of somata of anterior horn neurons of the lumbar spinal cord of seven patients with amyotrophic lateral sclerosis (ALS). Specimens from six age-matched, neurologically normal control individuals were included for comparison. Examination of presynaptic terminals revealed a wide range of changes not only in degenerated neurons (central chromatolytic neurons), but, to a lesser extent, in normal-appearing neurons. The alterations included dense conglomerates of aggregated dark mitochondria and presynaptic vesicles, bundles of neurofilaments, as well as marked increase of presynaptic vesicles. Our observations suggest that in patients with ALS a substantial synaptic alteration does take place in the early stages of anterior horn neuron degeneration and degeneration of axosomatic synapses of anterior horn neurons in ALS may be of consequence on lower motor neuron degeneration.

Determination of enamel protein synthesized by recombined mouse molar tooth germs in organ culture

Epithelial-mesenchymal interaction is a prerequisite for tooth morphogenesis. To study this interaction, inner enamel epithelium and dental papilla mesenchyme of molar tooth germs from a 16.5-day mouse embryo were dissociated enzymatically and cultured alone or after recombination. Characteristic matrix protein synthesized and secreted by recombined tooth germ was determined quantitatively by enzyme-linked immunosorbent assay. The protein was detected in the culture of recombined tooth germ but not of dissociated enamel epithelium alone. The amount of enamel protein increased until 8 days in culture. Morphological differentiation of the recombined epithelial rudiment into ameloblasts and enamel protein production were confirmed.

The mode of rabbit platelet shape change and aggregation induced by theonezolide-A, a novel polyketide macrolide, isolated from the Okinawan marine sponge Theonella sp

Theonezolide-A (TZ-A), a novel polyketide macrolide, isolated from the Okinawan marine sponge Theonella sp., caused a marked platelet shape change at low concentrations (0.2-0.6 microM). Increasing concentrations of TZ-A to 6 microM or more caused shape change followed by a small but sustained aggregation. In a Ca(2+)-free solution, TZ-A-induced aggregation was markedly inhibited, although the marked shape change was still observed. Aggregation stimulated by TZ-A increased in a linear fashion with increasing Ca2+ concentrations from 0.1 to 3.0 mM. Furthermore TZ-A markedly enhanced 45Ca2+ uptake into platelets. Aggregation induced by TZ-A was inhibited by Arg-Gly-Asp-Ser, an inhibitor of fibrinogen binding to glycoprotein IIb-IIIa, H-7 and staurosporine, protein kinase C inhibitors, or genistein and tyrphostin A23, protein tyrosine kinase inhibitors, whereas shape change was blocked by genistein and tyrphostin A23. H-7 or staurosporine did not affect the TZ-A-induced shape change. These results suggest that TZ-A-induced platelet shape change is not dependent on external Ca2+, whereas TZ-A-induced aggregation is caused by an increase in Ca2+ permeability of the plasma membrane. It is also suggested that both aggregation and shape change induced by TZ-A are associated with protein phosphorylation by protein kinase C and tyrosine kinase.

Blood pressure at health screening as a predictor of coronary heart disease in Kyoto

AIM

Most epidemiologic studies that have evaluated coronary risk factors have measured either mortality or morbidity of coronary artery disease (CAD) as endpoints. However, earlier detection and elimination of coronary risk factors are crucial. We therefore performed Master's double (i.e. 1.5 min x 2 = 3 min) two-step exercise electrocardiograph (ECG) test in apparently healthy asymptomatic subjects (men, n = 2274; women, n = 959) to elucidate the risk factors for early-stage CAD or silent myocardial ischemia.

METHODS

We examined the possible association of blood pressure at health screening and other suspected risk factors with exercise ECG test performance. The ischemic ECG response was determined by (1) > or = 0.5 mm horizontal or sagging S-T segment depression, (2) > or = 2.0 mm J-shaped S-T segment depression, or (3) T inversion in post-exercise ECG.

RESULTS

We found that 4.7% of men and 10.6% of women exhibited ischemic responses. Among males, the ischemic responders to the exercise ECG test had higher systolic and diastolic blood pressure. In addition, the male ischemic responders were older, had a higher obesity index, higher serum cholesterol, triglyceride, low-density lipoprotein (LDL)-cholesterol, protein, glucose, and uric acid levels, and a lower serum potassium level than normal responders. In contrast, the female ischemic responders to the exercise ECG test had higher systolic pressure, and higher serum cholesterol, LDL-cholesterol, and protein levels than normal responders. Mean blood pressure was correlated positively with most of the other coronary risk factors, and mild hypertensives and hypertensives had abnormal lipid, glucose, and uric acid levels in both sexes. A comparison of risk factors by age group revealed that only younger and middle-aged ischemic responders had higher blood pressure, serum cholesterol, and glucose levels than normal responders of both sexes, and that in older subjects all the differences between normal and ischemic responders became insignificant.

CONCLUSIONS

Elevated blood pressure at health screening, together with abnormal lipid and glucose metabolism, might be risk factors predicting early-stage or silent CAD. The elimination of these risk factors in younger men and women seems to be important.