Biomedical subjects

S Matsuda

Publications and source records attributed to S Matsuda.

At least 397 records · Page 22Linked to original sources

PubMed1994

Characterization of recombinant Xenopus MAP kinase kinases mutated at potential phosphorylation sites.

Xenopus mitogen-activated protein kinase kinase (MAPKK) previously inactivated with protein phosphatase 2A can be reactivated by serine phosphorylation catalyzed by a partially purified MAPKK kinase (MAPKK-K), and is phosphorylated by MAPK on a threonine residue. The sequence analysis of a threonine-phosphorylated tryptic peptide of Xenopus MAPKK from mature oocytes suggested that Thr388 is phosphorylated in vivo. A mutant MAPKK that has Thr388 changed to Ala (T388A-MAPKK) was not phosphorylated by purified MAPK, indicating that Thr388 is phosphorylated by MAPK. We then produced and analysed MAPKKs mutated at potential serine phosphorylation sites (S218A-MAPKK and S222A-MAPKK). The wild-type MAPKK (WT-MAPKKK), T388A-MAPKK and a kinase-deficient (K97S)-MAPKK were phosphorylated efficiently by MAPKK-Ks purified from Xenopus eggs, and WT-MAPKK and T388A-MAPKK became activated. In contrast, neither S218A-MAPKK nor S222A-MAPKK was phosphorylated and activated efficiently by the Xenopus MAPKK-Ks. Similarly, WT-MAPKK, but not S218A-MAPKK or S222A-MAPKK, was activated efficiently by an active Raf-1 immunoprecipitate. However, when the recombinant STE11, a putative MAPKK-K in S. cerevisiae, was used as a source of MAPKK-K, S218A-MAPKK as well as WT-MAPKK, but not S222A-MAPKK, was phosphorylated and activated. Furthermore, replacement of Ser222 with an acidic residue (S222E) elevated substantially the basal kinase activity of MAPKK, while replacement of Ser218 (S218E) did not. These results may suggest an essential role for Ser222 phosphorylation in activating Xenopus MAPKK.

Amino Acid Sequence↗

PubMed1993

Construction and characterization of new host-vector systems for the enforcement-cloning method.

The Escherichia coli host strains, TH1, TH2, TH3 alpha, TH4 and TH5, all trpR-, rpsL- and supE-, were constructed to constitutively express a trp promoter/operator (POtrp)-driven synthetic rpsLam+ gene encoding the streptomycin sensitivity (Sms) determinant (ribosomal protein S12). The applicability of these strains to the Sms-enforcement cloning procedure [Toba-Minowa and Hashimoto-Gotoh, Gene 121 (1992) 25-33] was examined on tryptophan-rich low-salt (LS) agar medium in combination with two reconstructed Sms-enforcement plasmid vectors, ampicillin-resistant (ApR) pKF2, and chloramphenicol-resistant (CmR) pKF3. The results indicated that (1) pKF2 enforced the Sms phenotype on TH1, TH2, TH4 and TH5, but not TH3 alpha, while pKF3 was effective on all the strains, (2) even without Sm, strains TH1, TH2, TH4 and TH5 harboring pKF2 rarely formed colonies on LS+Ap agar, and (3) TH2 harboring pKF3 hardly grew, forming tiny colonies only after two overnight incubations at 37 degrees C on LS+Cm agar. By using the AseI, BclI, StuI and EcoRI sites in POtrp-rpsL+4am of pKF2 and pKF3, it was revealed that enforcement cloning was applicable in the new host-vector systems on normal nutrient agar medium, except for a combination of TH3 alpha and pKF2, with the TH2 strain in combination with pKF2 or pKF3 seeming to be most suitable for enforcement cloning, even without Sm.

Amino Acid Sequence↗

PubMed1993

Functional and physical interaction of protein-tyrosine kinases Fyn and Csk in the T-cell signaling system.

The Src-like protein-tyrosine kinase Fyn is associated with T-cell antigen receptor. Transient expression of actively mutated Fyn, having Phe-528 instead of Tyr-528 or Thr-338 instead of Ile-338, in Jurkat T-cells stimulated the serum response element (SRE), 12-O-tetradecanoyl-phorbol-13-acetate response element, cyclic AMP response element, and c-fos promoter. The stimulation of SRE was particularly prominent not only with active Fyn but also with normal (wild-type) Fyn. SRE was also stimulated by both normal and active Lck. Furthermore, normal and active Fyn stimulated transcription from the IL-2 gene promoter when transfected cells were stimulated by concanavalin A plus 12-O-tetradecanoylphorbol-13-acetate. Under the same conditions, Lck did not stimulate IL-2 promoter unless it was activated by mutation. Interestingly, a mutant Fyn, which has deletions within the SH2 region and so is able to transform chicken embryo fibroblasts, did not stimulate either the c-fos or IL-2 promoter, suggesting the importance of this region in T-cell signaling. Csk, which phosphorylates tyrosine residues in the negative regulatory sites of Src family kinases, down-regulated Fyn- and Lck-mediated stimulation of the serum response element and Fyn-mediated enhancement of IL-2 promoter activity. These data suggest that Fyn and Lck, whose activities are regulated by Csk, are involved in different phases of T-cell activation.

Amino Acid Sequence↗

PubMed1993

17 beta-estradiol mimics ligand activity of the c-erbB2 protooncogene product.

We report here the physical and functional interaction of estrogen with the ErbB2 protein p185c-erbB2. The ErbB2 protein immunoprecipitated from estrogen-treated [10(-8) to 10(-6) M 17 beta-estradiol (E2)] RC cells showed higher autophosphorylation activity than that from untreated cells. Likewise autophosphorylation activity of ErbB2 protein from untreated cells was stimulated in vitro by E2. In addition, E2 treatment induced down-regulation of ErbB2 protein from the detergent-soluble fraction of the RC cells within 15 min. E2 also induced morphological transformation of the RC cells but not of the parental NIH 3T3 cells, which express little c-erbB2 under the same experimental conditions. This morphological transformation of RC cells was reversed by tamoxifen. However, E2 treatment did not induce anchorage-independent growth of RC cells. Scatchard analysis revealed E2 binding to the ErbB2 protein on RC cells; the Kd value was 2.7 nM. E2 did not bind appreciably to the parental NIH 3T3 cells or cells expressing an ErbB2 protein lacking most of its extracellular domain. These data suggest that estrogen plays an important role in ErbB2-mediated signaling.

3T3 Cells↗

PubMed1993

Distribution of prosaposin-like immunoreactivity in rat brain.

Prosaposin is the precursor for saposins A, B, C, and D, which are small lysosomal proteins required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. With a monospecific anti-saposin C antibody, which cross-reacts with prosaposin but not with saposin A, B, or D, the present immunoblot experiments showed that the rat brain expresses an unprocessed approximately 72 kDa protein (possibly prosaposin) and little saposin C. Regional analysis demonstrated that prosaposin is abundant in the brainstem, hypothalamus, cerebellum, striatum, and hippocampus, and less abundant in the cerebral cortex. Consistent with this finding, prosaposin-like immunoreactive neurons and fibers as revealed by immunohistochemistry were observed frequently in subcortical regions. The medial septum, diagonal bands, basal nucleus of Meynert, ventral striatum, medial habenular nucleus, and motor nuclei of cranial nerve had significant numbers of immunoreactive neurons. There were also nerve fibers with prosaposin-like immunoreactivity in several projection fields of the above nuclei. Other brain areas that contained prosaposin-like immunoreactive neurons and/or processes were: several brain nuclei (nucleus caudate putamen, globus pallidus, substantia nigra, red nucleus) constituting the so-called extrapyramidal system, reticular thalamic nucleus, entopeduncular nucleus, mammillary nuclei, auditory relay nuclei, cerebellum, sensory cranial nerve nuclei, and the reticular formation. The distribution pattern of prosaposin is apparently different from that of other neuroactive substances so far examined, and thus prosaposin may be involved in novel central events.

Animals↗

PubMed1993

Transient increase in endogenous basic fibroblast growth factor in neurons of ischemic rat brains.

An antiserum against basic fibroblast growth factor (bFGF) was shown to recognize an 18-kDa protein (possibly bFGF) in crude neocortical extracts by immunoblot and used to investigate the changes of bFGF immunoreactivity in neurons and astrocytes of the cerebral cortex of rats 1-21 days after unilateral occlusion of the middle cerebral artery (MCA). The mildly ischemic neocortex exhibited no signs of cell loss or degeneration in Nissl-stained sections 1-14 days after MCA occlusion, but it contained pyramidal cell bodies and processes with more intense bFGF immunoreactivity than did the control neocortex. bFGF immunoreactivity in the ischemic hemisphere gradually declined in intensity and by 21 days after MCA occlusion, it had reached the control level. On the other hand, there were many bFGF immunoreactive astrocytes in the primary olfactory cortex on the side of infarction. These findings suggest that MCA occlusion causes an increase in bFGF content not only in astrocytes but also in neurons, depending on the severity of the ischemic insult in individual cortical regions. The transient augmentation of bFGF expression or accumulation in mildly ischemic pyramidal neurons but not in astrocytes is in line with previous studies suggesting the neurotrophism of exogenously applied bFGF.

Animals↗

PubMed1993

Phosphorylation of Xenopus mitogen-activated protein (MAP) kinase kinase by MAP kinase kinase kinase and MAP kinase.

Xenopus 45-kDa mitogen-activated protein (MAP) kinase kinase (MAPKK) is a serine/threonine/tyrosine kinase, which activates MAP kinase (MAPK) by phosphorylating its threonine and tyrosine residues. MAPKK is active only when its threonine and/or serine residues are phosphorylated. We have identified from Xenopus eggs two protein kinases responsible for phosphorylation of MAPKK. The two kinases are separated by Sephacryl S-300 gel filtration chromatography. The higher molecular weight kinase phosphorylates MAPKK previously dephosphorylated and inactivated by phosphatase 2A treatment on mainly serine and slightly threonine residues, and reactivates the MAPKK, and is thus assumed to work as MAPKK kinase (MAPKKK) in vivo. The lower molecular weight kinase, identified as MAPK, phosphorylates the dephosphorylated MAPKK on mainly threonine and faintly serine residues, but does not reactivate the MAPKK activity. As Xenopus MAPKK contains a single phosphorylation consensus sequence (PXT388P) for MAPK in the C-terminal region, this T388 residue may be a major phosphorylation site catalyzed by MAPK. Thus, Xenopus MAPKK is phosphorylated in mature oocytes by not only an upstream kinase, MAPKKK, but also a downstream kinase, MAPK.

Amino Acid Sequence↗

PubMed1993

Decreased messenger RNA of arachidonate 12-lipoxygenase in platelets of patients with myeloproliferative disorders.

On the basis of the previous work by Okuma and Uchino [Blood 54, 1258-1271, 1979], three patients with myeloproliferative disorders were investigated with a special reference to arachidonate 12-lipoxygenase in their platelets. The cytosol of the patients' platelets showed a markedly reduced activity of arachidonic acid oxygenation to 12-hydroperoxy acid. A peroxidase-linked immunoassay for the 12-lipoxygenase demonstrated only 7-12% of the normal level of the enzyme protein in the cytosol fraction of platelets. Furthermore, 12-lipoxygenase mRNA level was determined quantitatively by a reverse transcriptase-polymerase chain reaction with an internal standard cRNA which was synthesized by in vitro transcription of human platelet 12-lipoxygenase cDNA with a 105-bp deletion. The 12-lipoxygenase mRNA content was 4.7 +/- 2.0 (mean +/- S.D.) ng/10(11) platelets in 13 normal subjects. In contrast, the mRNA content was as low as 0.15, 0.11 and 0.10 ng/10(11) platelets in the three patients. Taken together, the 12-lipoxygenase deficiency in these patients was attributable to the decreased 12-lipoxygenase mRNA level and thus the impaired synthesis of the enzyme protein in their platelets.

Antibodies, Monoclonal↗

PubMed1993

An immunohistochemical study of basic fibroblast growth factor in the developing chick.

An antiserum against basic fibroblast growth factor (bFGF) was characterized by immunoblot experiments and used to investigate immunohistochemically the appearance of bFGF-like immunoreactivity in the developing chick. Crude homogenates of chick embryos at every developmental stage, when subjected to immunoblotting with the use of bFGF antiserum, exhibited a main band with the same molecular weight (18 kDa) as bovine bFGF. With immunohistochemistry, bFGF immunoreactivity (bFGF-IR) was detected exclusively in intracellular components of various tissues at different stages of development; bFGF-IR appeared initially on embryonic (incubation) day 3 (E3) in the myotome, on E12 in the spinal cord and ganglia, on E8 in chondrocytes and osteoblasts of the vertebrae, and on E10 in the esophageal epithelium. Immunoreaction products were present either in the cytoplasm or in the nuclei, depending on the types of individual bFGF-containing cells; developing chondrocytes and cells in the stratum basale of the esophagus exhibited intense immunoreactions exclusively within the nuclei, and the other cells mainly within the cytoplasm. Moreover, bFGF-IR was observed in discrete regions of these tissues at different stages; the epithelium of the esophagus contained bFGF-IR in all layers on E10 to E18 with a superficial-to-basal gradient, but it began to exhibit bFGF-IR only in the stratum basale after E20; and bFGF-IR was more abundant in hypertrophic chondrocytes than in proliferating ones. As chicks aged, bFGF-IR decreased or disappeared in the muscles, vertebrae and esophageal epithelium, but neuronal bFGF increased in intensity until the perinatal period and thereafter remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Basic fibroblast growth factor-like immunoreactivity in the rat trigeminal sensory system and peri-oral skin with vibrissae.

We have characterized an antiserum against basic fibroblast growth factor (bFGF) by immunoblot, investigated the location of bFGF-like immunoreactivity (bFGF-IR) in the trigeminal sensory system and perioral skin endowed with vibrissae, and demonstrated the site of bFGF mRNA expression in the vibrissae by in situ hybridization histochemistry. Light-microscopic immunohistochemistry has demonstrated that bFGF-IR is present not only in trigeminal ganglion neurons and their central and peripheral processes, but also in cells of the matrix, external root sheath and papillae of vibrissae and the stratum basale of the stratified squamous epithelium of the skin. Electron microscopy has revealed intense bFGF-IR mainly in cytoplasmic regions, other than the lumen of rough endoplasmic reticulum and the Golgi apparatus, in trigeminal ganglion neurons, in fibroblast-like cells in the papillae, and in capsules of vibrissae. In contrast, actively proliferating and/or differentiating cells in the matrix of vibrissae have intensely stained euchromatin and weakly labeled cytoplasm that, unlike that of the aforementioned cells, contain immunoreaction products in discrete spots less than 100 nm in diameter, implying the generation of different molecular forms of bFGF in cells of the matrix and papillae. Moreover, the accumulation of bFGF in the euchromatin appears to take place in cells at non-mitotic stages (possibly interphases), characterized by a conspicuous nucleolus and well-developed nuclear envelope. A digoxigenin-labeled cRNA probe for the demonstration of bFGF mRNA gives conspicuous hybridization signals mainly in the matrix of vibrissae. These findings suggest that bFGF is involved in the growth and differentiation of matrix cells during certain periods of the cell cycle and that it acts as a non-mitogenic mediator in the adult trigeminal sensory system.

Animals↗

PubMed1993

A meiotic DNA polymerase from Coprinus cinereus: further purification and characterization.

A meiotic DNA polymerase that is present at a high level of activity in meiotic cells of a basidiomycete, Coprinus cinereus, was purified to near homogeneity using synthetic RNA homopolymer [poly(C)] cellulose column chromatography. This report presents the first extensive purification and characterization of any eukaryotic DNA polymerase having a role in meiosis. This enzyme is a single polypeptide with a molecular mass of 65,000. Activity in this enzyme requires magnesium ions and occurs at an optimal pH of 7.5. It is strongly inhibited by dideoxythymidine triphosphate but is relatively insensitive to aphidicolin and N-ethylmaleimide and can use poly(C)/oligo(dG)12-18 as a template-primer. Polymerase activity can be found only in cells at meiotic prophase, even though the enzyme has been identified in somatic cells in an inactive state using immunoblot analysis. Its distinctive distribution makes possible a genetic and biochemical analysis of functional role of a meiotic DNA polymerase in meiotic recombination, repair and synthesis.

Aphidicolin↗

PubMed1993

Structural, functional and evolutionary implications of the three-dimensional crystal structure of murine interferon-beta.

The crystal structure of recombinant murine interferon-beta as elucidated by Senda et al. (Proc. Jap. Acad. 66B: 77-80 (1990); EMBO J. 11: 3193-3201 (1992)) appears to represent the basic structural framework of all Type I interferons including interferons-beta and all subtypes of interferons-alpha of various mammalian origin. Now the huge accumulated data on the structure-activity relationship of Type I interferons using various chemical and genetic techniques can be systematically evaluated in terms of the three-dimensional structure. Structural comparison with other cytokines, for which three-dimensional structures have been established, including interferon-gamma and considerations on the evolution of cytokines and cytokine receptors are also given.

Amino Acid Sequence↗

PubMed1993

Japanese patients with chronic fatigue syndrome are negative for known retrovirus infections.

Although chronic fatigue syndrome (CFS) is known to be the syndrome that begins with an acute flu-like illness that may be due to the exposure to an infectious agent, there has been no convincing evidence on the causative agents. Recently, human T-lymphotropic virus type II (HTLV-II)-like virus has been reported to be associated with the CFS by using HTLV Western blot analysis and polymerase chain reaction. However, some investigators could not detect HTLV-II by indirect immunofluorescence analysis. Lately, CFS patients have been reported in Japan. We detected all 30 tested patients with CFS were seronegative for HTLV-II, HTLV-I and HIV by specific peptide ELISA and Western blot. Further, PCR analysis was negative for HTLV-II and retrovirus was not detected by coculture method with patients' PBMC. Thus, known human retrovirus infections do not cause a CFS in Japan.

Blotting, Western↗

PubMed1993

Characteristics of IgA antibodies against HIV-1 in sera and saliva from HIV-seropositive individuals in different clinical stages.

IgA antibodies were analysed in sera and saliva from 40 HIV-1 seropositive individuals. The level of total IgA in serum was elevated according to the progress of the disease. IgA antibodies against p24 and gp160 were detected in the asymptomatic phase of infection. However, they declined in the symptomatic phases in contrast with IgG antibodies. Interestingly, three patients in the symptomatic phase who showed high levels of IgA antibodies were all in relatively good clinical condition. The IgG and IgA antibodies in saliva declined in the symptomatic phase. The level of IgG anti-p24 antibodies in saliva correlated with that in serum, suggesting that IgG anti-p24 antibodies in saliva originated from those in the serum. These results indicate that IgA antibodies are regulated independently from IgG antibodies and that the mucosal immune system is impaired early in the symptomatic phase of HIV infection, which starts with mucosal impairment. Detection of IgA antibodies may be useful for prognosis of the disease in HIV-infected individuals. The results indicate also that treatment for the impaired IgA mucosal immune system should be taken into consideration.

AIDS-Related Complex↗

PubMed1993

Assessment of Chlamydia trachomatis-specific IgA and IgG serum antibodies in genitourinary Chlamydia trachomatis infection--comparative study between HITAZYME and IPAzyme.

We assessed the C. trachomatis antibody assay kit HITAZYME (Hitachi Chemical Co., Ltd.) using clinical specimens. This kit is based on an enzyme immunoassay (EIA) which utilized purified Chlamydia trachomatis outer membrane antigen as the solid phase antigen. Twenty-nine untreated male urethritis patients, 816 pregnant housewives, 188 cervicitis patients, and 76 pelvic inflammatory disease patients were tested. Agreement between the HITAZYME test and antigen detection in infected area was assessed, and a comparison was made with IPAzyme (a commercially available indirect immunoperoxidase assay kit). 1) Summary of HITAZYME and IPAzyme IgA: Agreement between the two assays was relatively good, i.e., 82.6% (916/1109). However, 5.5% (61/1109) were HITAZYME (-), IPAzyme (+), and 11.9% (132/1109) were HITAZYME (+), IPAzyme (-). Thus, in quite a few cases the results did not agree. IgG: Agreement between the two assays was 73.7% (817/1109). Agreement was relatively low, 24.4% (271/1109) were HITAZYME (-), IPAzyme (+). 2) In the cases of disagreement, more specific Western blot analysis was performed to check the reactivity of the anti-C. trachomatis antibody. When IgA was used, agreement between HITAZYME and Western blot analysis was 69.6% (16/23), and agreement between IPAzyme and Western blot analysis was 30.4% (7/23), whereas when IgG was used, agreement between HITAZYME and Western blot analysis was 80.0% (12/15), and agreement between IPAzyme and Western blot analysis was 20.0% (3/15). There was significantly greater agreement with HITAZYME than with IPAzyme. In other words, HITAZYME had greater specificity when reacted with C. trachomatis antigen than IPAzyme. 3) The IgA antibody-positive rate in antigen (+) cases (male urethritis: 72.7%, pregnant housewives: 65.7%, cervicitis: 70.3%, pelvic inflammatory disease: 70.0%) was significantly (p < 0.01) higher than in antigen (-) cases (male urethritis: 16.7%, pregnant housewives: 13.6%, cervicitis: 22.6%, pelvic inflammatory disease: 30.4%). Therefore, IgA antibody can serve as a suitable indicator for active infection. 4) The IgG antibody-positive rate in antigen (-) female cases was 15.5% using HITAZYME and significantly (p < 0.01) lower than with IPAzyme. HITAZYME had greater specificity than IPAzyme. In conclusion, HITAZYME has relatively good sensitivity and specificity. Moreover, since it is an EIA assay, it allows objective evaluation of results. It permits processing of a large number of specimens because it is easy to perform. Thus, HITAZYME is a superior antibody assay for C. trachomatis. It can be used when antigen tests are difficult to perform. It is strongly anticipated that HITAZYME will be able to be used clinically as a screening test.

Chlamydia Infections↗

PubMed1993

[Digit preference in birth weight data of obstetric facilities].

An investigation on instrumentation of birth weight in obstetric facilities was made in the northern part of Fukuoka Prefecture from March 1989 to January 1991. A distribution of 3000 cases from 100 facilities was analyzed for the purpose of clarifying the reliability of the data. The following results were obtained. 1) Birth weights measured by analogue scales (1530 cases) showed digit preference in all distributions of the whole, the lower three digits and the lower two digits. But those measured by digital scales (1470 cases) did not show any distortion in these three distributions. 2) There were significant differences among mean birth weights calculated from the intact data, and 50g-, 100g- and 500g-interval frequency histograms in analogue scales (p < 0.01). But in digital scales there were no significant differences among mean birth weights. Rounding error was supposed to be one of the main causes of this discrepancy. Digital scales are superior to other types of scales because they do not show distribution distortion of the data. The reliability of the birth weight data is different among the types of scales. We have to consider which type of scale is used when we refer to annual changes or differences among areas in mean birth weights.

Biometry↗

PubMed1993

[Secular changes of the mean birth weight in Japan during the past 20 years (single births, 1969-88)].

Using vital statistics (1981-1988) of the Japanese government, the mean birth weight (MBW) classified by sex was calculated from a birth weight distribution of the single births with 500g intervals for all Japan, prefectures and regions. These MBWs were linked with the MBW of 1969-1980 in our previous reports (Ref. 1) 2)). The MBWs of single births for twenty years (1969-1988) were investigated and it was pointed out that the MBWs classified by area (all Japan, prefectures and regions) were on the decrease recently and that the areal differences of the MBW were becoming large. For all Japan a secular change in the MBW was discussed for the term of a standard deviation, a skewness, a kurtosis, and relative frequencies of less than 2500g (weight class 1), those from 2500g to 3999g (weight class 2) and those of 4000g or more (weight class 3). These investigations revealed that birth weights of Japan have had a tendency to have a small standard deviation, a negative skewness, and a large kurtosis. Weight class 1 decreased until 1976 and increased after this year. Weight class 2 was on the increase up to 1988, and weight class 3 increased until 1973 and decreased afterward, as if it were accompanied by the MBW. For the purpose of confirming the contribution of each weight class to the annual change of the MBW, an analytical method for the weight frequency distribution was proposed as follows. Let M, M', pi and pi' represent the MBW of a given year (year A), the MBW of an another year (year B), the relative frequency of the i-th weight class in year A and that in year B, respectively. Suppose that M(i)'' represents the MBW when only the i-th weight class has pi as a relative frequency even in year B. Then, as the result of a fairly simple calculation, the difference between the MBW in year A and that in year B, M'-M, is obtained as follows; M'-M = sigma (1-pi') (M'-M(i)''). Therefore, the amount (1-pi') (M'-M(i)'') is able to be considered as a share of the i-th weight class in relation to the difference of M'-M. Accordingly, the share proportioned to the summation of the absolute amount [formula: see text] may represent the degree of the contribution of the i-th weight class to the difference, M'-M.(ABSTRACT TRUNCATED AT 400 WORDS)

Birth Weight↗

PubMed1993

[Correction of the mean birth weight calculated from a frequency distribution (Japan, single births, 1969-88)].

Recently the mean birth weight (MBW) of Japan is on the decrease. This phenomenon started in 1976 and continues up to the present as of 1988. Various factors accounting for this phenomenon have been considered and discussed by several researchers. They were interested in social, cultural and economic factors as well as factors influencing community health status. Although the above factors seem to be important, one problem connected with calculation of MBW is worth discussing. The MBW was calculated from a frequency distribution because of a limitation of the source material. The accuracy of calculation of statistics from a frequency distribution depends on the assumption that few frequencies fall on boundaries, but birth weight measurements are apt to fall on figures having 0 at the end because of the properties of weighing scales. Suppose that the exact weight of an infant is 2996g. If his weight is read to the nearest figure having 0 at the end by rounding, it is recorded as 3000g on the birth certificate. Then, in a frequency distribution whose class interval is 500g, his weight is treated as 3250g in calculation of the mean. But some improvements of the methods of weighing, for example, utilization of a scale displaying a digital value of weight may result in a greater chance that his weight is recorded as 2996g. Then, in the same frequency distribution, his weight is treated as 2750g in calculation of the mean. Therefore, an improvement of the method of weighing produces the phenomenon that MBW decreases even if all the original birth weights did not change. Exact relative frequency, recorded as just 2500g, that is mentioned secondarily in the Vital Statistics of Japan has been decreasing consistently since 1969. This year is the oldest in the above source having frequency distributions of single birth infants. This fact shows that methods of weighing have been improved as the years pass. In this paper we tried to correct MBW by using the relative frequency recorded as exactly 2500g. Two kinds of widths where rounding would be executed were estimated from a frequency polygon. We obtained the following results. 1) The correction equation is represented as ld approximately; where l is a class interval (500g in this paper) and d is calculated by d = Q/(pa + pa+1 + Z) as a mean value in a certain sense and by d = 2Q/(pa + pa+1 + Z) as a maximum value.(ABSTRACT TRUNCATED AT 400 WORDS)

Birth Weight↗