Biomedical subjects

Z D Jiang

Publications and source records attributed to Z D Jiang.

At least 55 records · Page 3Linked to original sources

PubMed1995

Maturation of the auditory brainstem in low risk-preterm infants: a comparison with age-matched full term infants up to 6 years.

Whether preterm birth has a significant effect on the maturation of the human brain remains an equivocal issue. Since experience plays a crucial role in the development of the brain, it is conceivable that extra-uterine preterm exposure could exert some effects on the maturation of the developing human brain. The present study compared the post-term maturation of the central components of brainstem auditory evoked response (BAER) in low risk preterm infants with that of age-matched full term infants up to 6 years. The preterm infants demonstrated similar maturational profiles to those of the term infants in both interpeak intervals and amplitude measures. No systematic, statistically significant differences were found between the preterm and term infants in any of the BAER variables although the I-V interval tended to be slightly shortened in the prematurely born infants. These results suggest that preterm birth or earlier exposure to sound environment extra utero is unlikely to lead to significant neurophysiological consequence in the developing auditory brainstem of low risk infants.

Aging↗

PubMed1995

Long-term effect of perinatal and postnatal asphyxia on developing human auditory brainstem responses: peripheral hearing loss.

Peripheral hearing was assessed by examining brainstem auditory evoked responses (BAER) in children who suffered perinatal or postnatal asphyxia, particularly in those with residual neurodevelopmental deficits, to investigate the long-term effect of asphyxia on the developing auditory sensitivity. The BAER data were collected at least 6 months after the episode of asphyxia. Of the children who suffered perinatal asphyxia, hearing loss was found more frequently in those who exhibited residual neurodevelopmental deficits (17.1%) than in those who did not (6.3%), but this difference did not reach statistical significance. This implied that the long-term effect of perinatal asphyxia on the peripheral auditory system and its effect on the central nervous system may be relatively discrete or not closely correlated. The occurrence of hearing loss did not appear to be closely related to the degree of perinatal asphyxia, although hearing loss occurred more frequently in the children after severe asphyxia compared to those after mild asphyxia. There was no evidence for permanent hearing loss in the children who survived severe, prolonged postnatal asphyxia and exhibited residual neurodevelopmental deficits. These findings suggest that a critical period of particular sensitivity to the effect of hypoxia may exist during the development of the human peripheral auditory system. This period may range from some time prenatally to some time shortly after birth, probably the third postnatal month. After that, hypoxia is unlikely to lead to permanent hearing loss.

Age Factors↗

PubMed1995

HEp-2 cell-adherent Escherichia coli in patients with human immunodeficiency virus-associated diarrhea.

Diarrhea occurs commonly in African human immunodeficiency virus (HIV) infections. A case-control (HIV-positive vs. -negative) study of adults with diarrhea was done in Lusaka, Zambia, to determine the prevalence of intestinal infection by HEp-2 cell-adherent Escherichia coli. Adherent E. coli were more common in HIV-positive patients with acute diarrhea than among HIV-negative controls (60% vs. 33%) and were found significantly more often in HIV-positive patients with chronic diarrhea than among HIV-negative controls with chronic diarrhea (79% vs. 17%, P < .002). Adherent strains were found significantly more often among HIV-positive patients (69%) than in 22 asymptomatic subjects (36%, P < .02). The HEp-2 cell adherence of the E. coli strains did not show a common pattern. Adherent bacteria were also observed in colonic biopsies from 32% of Zambians with chronic diarrhea who underwent endoscopy. Adherent E. coli may be an important cause of HIV-associated diarrhea in Zambia.

Acute Disease↗

PubMed1995

Development of human peripheral hearing revealed by brainstem auditory evoked potentials.

Development of human peripheral hearing from birth to 6 years was investigated by recording brainstem auditory evoked potentials (BAEPs). The threshold of BAEPs decreased rapidly during the first 3 months after birth (2.7 dB/week during the neonatal period, 2.6 dB/month at 1-3 months), after which further decrease occurred more slowly but continued through 1 year of age (0.26 dB/month at 3-12 months). A few days after birth, the threshold was 18 dB higher compared to the adults, and progressively decreased to 10, 5 and 2 dB at 1, 3 and 12 months, respectively. The latencies of waves I and V decreased as a function of age at a rate of 0.01 and 0.05 ms/week during the neonatal period, 0.02 and 0.10 ms/month at 1-3 months and 0.014 and 0.076 ms/month at 3-12 months, respectively. Adult latency value was attained by 2 and 4 years for waves I and V, respectively. These findings suggest that although the ear is reported to be almost adult-like at birth, the immaturity in neural functional properties limits auditory sensitivity during early childhood. It appears that human peripheral hearing threshold decreases rapidly through the third postnatal month and thereafter continues to improve slowly through early childhood. It is postulated that the first 3 months after birth are likely to be a critical period in postnatal development of human peripheral hearing.

Auditory Threshold↗

PubMed1994

Intestinal secretory IgA immune response against human immunodeficiency virus among infected patients with acute and chronic diarrhea.

Diarrhea is common in patients infected with the human immunodeficiency virus (HIV) in Africa. There has been speculation that HIV itself may cause some of the enteropathy seen. The intestinal secretory IgA (sIgA) response was used to evaluate HIV intestinal infections in Zambian patients with acute and chronic diarrhea. sIgA was extracted from stool specimens and evaluated by an ELISA. Seven (58%) of 12 HIV-positive patients with acute diarrhea and 25 (69%) of 36 HIV-positive patients with chronic diarrhea showed an sIgA response to HIV p24, compared with 1 of 10 HIV-positive patients without diarrhea (P < .025 for acute and P < .001 for chronic diarrhea). The mean duration of diarrhea was significantly longer in patients showing an anti-p24 response. An sIgA response to HIV antigens occurs commonly in infected patients with diarrhea and may provide further evidence of an etiologic role of HIV in the diarrhea associated with AIDS.

Acute Disease↗

PubMed1993

Brainstem auditory evoked responses from birth to adulthood: development of wave amplitude.

Brainstem auditory evoked response (BAER) was recorded in children from birth to 6 years and adults to study the development of wave amplitude. The amplitudes of all BAER waves increased with age, the greatest changes occurring during early infancy. Adult values were reached at 6 months of age for wave I and 2 years for wave V. The two waves continued to increase above the adult values until the highest amplitude value was reached at 3 years for wave I and 5 years for wave V. Subsequently, the amplitudes decreased towards the values in adults. The V/I amplitude ratio, which was slightly than the adult value shortly after birth, decreased during the first year of life and reached the minimum value between 1 and 4 years. Thereafter, it increased towards the adult value. Throughout the maturational stages the ratio was smaller than in adults. The amplitude of wave V was relatively stable and its variation was much smaller than those of wave I and V/I amplitude ratio. Lower normative limits of these amplitude measures were given to provide a reference baseline for further study under the similar experimental conditions. We suggest that, in light of age-related differences of the V/I ratio, the normative criteria for the amplitude ratio should be established in relation to age. The amplitude of wave V is recommended to be useful in some clinical situations.

Adult↗

PubMed1992

Unique metabolites of eicosapentaenoic acid interfere with corpus luteum function in the ewe.

Experiments were conducted to determine the in vivo and in vitro effects of metabolites of eicosapentaenoic acid on ovine luteal function. Injection of 750 micrograms methyl eicosapentaenoic acid (EPA) or methyl 12(R),13(S)-dihydroxyeicosapentaenoic acid (12,13-diHEPE) into the ovarian artery of ewes on day 10 of the estrous cycle caused a reduction in serum concentrations of progesterone by 48 h posttreatment compared with levels of this steroid in arachidic acid-treated controls (p < 0.005). Although mean serum concentrations of progesterone in methyl EPA-treated ewes during the remainder of the cycle did not differ from those in control ewes, levels in methyl 12,13-diHEPE-treated ewes remained significantly suppressed. Duration of the estrous cycle did not differ among treatment groups (p > 0.05), but more of the methyl 12,13-diHEPE-treated animals (3/5) had exhibited estrus within 3 days after injection than methyl EPA-treated (1/5) or control ewes (0/5). Slices of corpus luteum removed from ewes on day 10 of the estrous cycle were incubated with arachidic acid (controls), 12,13-diHEPE or docosatetraenoic acid (DTA). Regardless of fatty acid treatment, all tissues retained the ability to produce basal levels of progesterone during subsequent incubation. Luteal slices previously exposed to arachidic acid or DTA exhibited an increase in progesterone production in response to subsequent treatment with LH (p < 0.05). In contrast, luteal slices incubated with 12,13-diHEPE did not respond to LH with a significant increase in production of this steroid above that observed in controls. All tissues displayed a marked increase in progesterone synthesis upon treatment with 8-Br-cAMP relative to incubation of tissue alone (p < 0.001). Subcellular distribution of [14C]-12,13-diHEPE in luteal cells after incubation revealed that the majority of the fatty acid was associated with the plasma membrane. These data suggest that metabolites of eicosapentaenoic acid with hydroxyl groups on adjacent carbon atoms interfere with luteal function in the ewe, perhaps in part by altering luteal response to LH.

Animals↗

PubMed1992

Development of the brainstem auditory pathway in low birthweight and perinatally asphyxiated children with neurological sequelae.

Low birthweight (LBW) and perinatal asphyxia are known to be high-risk factors for a number of neurodevelopmental deficits. In this study, we analyzed brainstem auditory evoked response (BAER) in 18 LBW and 36 perinatally asphyxiated children with non-progressive neurological sequelae after the age of 6 months to inspect and compare the long-term influence of LBW and perinatal asphyxia on the brainstem auditory pathway. The typical changes in the BAER of children born with LBW were slightly shorter III-V interpeak interval and smaller III-V/I-III interval ratio than normal controls. On the contrary, the abnormalities in the BAER of 36 children surviving perinatal asphyxia were characterized by a reduction of the amplitude of wave V with normal intervals. This discrepancy in the BAER between the children born with LBW and those with perinatal asphyxia implies that the two high-risk factors exert different long-term influences on the development of the brainstem auditory pathway. It is hypothesized that these characteristic changes may be indicative of a major influence of LBW on the generators contributing to wave III and that of asphyxia on the generators contributing to wave V. An increase in response threshold with abnormal latency-intensity function was found in 11% of the LBW children and 19% of the asphyxiated children, suggesting that sensorineural hearing impairment occurred more frequently in children surviving perinatal asphyxia than in those born with LBW. Follow-up study demonstrates that the abnormalities in the brainstem auditory pathway of LBW and asphyxiated children after the age of 6 months is likely to be persistent.

Asphyxia Neonatorum↗

PubMed1991

An aldehyde-containing galactolipid from the red alga Gracilariopsis lemaneiformis.

An unprecedented aldehyde-containing digalactosyldiacylglycerol (DGDAG) has been isolated from the red alga Gracilariopsis lemaneiformis and structurally defined. Its structure was determined as 1-O-[5-hydroxy-12-oxo-dodeca-6(E),8(E),10(E)-trienoyl]-2-O-p almitoyl-3-O- [-beta-D-galactopyranosyl-6,1-alpha-D-galactopyranosyl]-glycerol by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and degradation to simple fragments. The identification of this aldehyde-containing DGDAG from G. lemaneiformis, in addition to our previous findings of unusual galactolipids, further indicates that this alga has unique lipoxygenase capacities.

Aldehydes↗

PubMed1991

Brainstem auditory evoked responses from birth to adulthood: normative data of latency and interval.

Development of wave latency and interpeak interval (IPI) in brainstem auditory evoked responses (BAER) from birth to adulthood was examined. Adult equivalence was reached for most wave latencies and IPIs between the ages of 9 months and 3 years. The observation of the III-V/I-III interval ratio suggests that after term data the I-III IPI decreases more than the III-V IPI. I-III, III-V and I-V IPIs shortened from the l-month old group to the 4-6 year old group by 22%, 15% and 19% respectively. The III-V/I-III interval ration may be a useful BAER measure. Normative data of various BAER measures at different ages are presented. The slope of the L-I function for wave V was slightly steeper in younger groups than in older groups (40 microseconds/dB in the 1-month old group 32 microseconds/dB in the adult group). This change which was accompanied by an age-related difference in the absolute wave latency. It is suggested that age-dependent norms should be used in evaluation of the L-I function.

Adult↗

PubMed1991

Intestinal secretory immune response to infection with Aeromonas species and Plesiomonas shigelloides among students from the United States in Mexico.

Intestinal secretory IgA (sIgA) response or lack of response among adults in Mexico with diarrhea was used as an indicator of enteropathogenicity of Aeromonas species and Plesiomonas shigelloides. sIgA was extracted from stool specimens obtained at day of presentation and 5 days later. Total sIgA was standardized, and specific sIgA titer against the organism being shed by each patient was determined. Western blotting was used to determine which microbial antigens elicited an intestinal sIgA response. Of 12 subjects shedding Aeromonas sobria or Aeromonas hydrophila, 11 had a fourfold or greater sIgA titer rise against the infecting strain. Western blotting showed that somatic lipopolysaccharides were the immunodominant antigens. No sIgA titer rises were detected among two patients shedding Aeromonas caviae or in 14 shedding P. shigelloides. This study provides further evidence of the significance of A. sobria and A. hydrophila as pathogens in acute diarrhea but raises additional questions about the role of P. shigelloides, at least in US adults with travelers' diarrhea.

Adult↗

PubMed1991

Development of early and late brainstem conduction time in normal and intrauterine growth retarded children.

Development of early (I-III) and late (III-V) brainstem conduction time (BCT) in the brainstem auditory evoked responses was examined and compared in 178 appropriate-for-gestational-age (AGA) and 24 small-for-gestational-age (SGA) children from birth to 6 years of age. In AGA children, the III-V/I-III interval ratio increased with age from birth to 2 years and remained relatively steady. This indicates that the development of the early and late BCT, or probably the lower and upper brainstem is not synchronous during early childhood, with a slightly faster development of the early BCT relative to the late BCT. In SGA children, the I-V, I-III and III-V intervals showed similar developmental trends to those in AGA children. However, the III-V/I-III ratio followed a developmental course which differed remarkably from that in AGA children. The ratio decreased slightly with age up to 2 years and was consistently smaller than in normal children after 1 year, indicating that the relative development of early and late BCT deviates from normal. This finding suggests that prenatal factors responsible for intrauterine growth retardation could alter the late or long-term development of the nervous system, resulting in sub-optimal outcome.

Age Factors↗

PubMed1991

Intensity effect on latency and interval of human BAER.

Intensity effect on wave latency and interval (IPI) in brainstem auditory evoked responses (BAER) from birth to adulthood was investigated. The L-I functions were slightly steeper in younger groups than in older groups, which was associated with age-related difference in the absolute latencies. Wave I latency in most age groups exhibited two "transitional" responses: one at 70 dB HL or, sometimes, at 60 dB HL and the other mostly at 20 dB HL. As click intensity decreased, the I-III IPI tended to decrease slightly while the III-V IPI tended to increase slightly in most age groups. Since the I-V IPI was constant at various intensities which could be attributed to a slight change in the morphology of wave III with altering intensity.

Acoustic Stimulation↗

PubMed1991

Amplitude change with click rate in human brainstem auditory-evoked responses.

The effect of click rate on wave amplitude of human brainstem auditory-evoked response (BAER) was examined at repetition rates of 10, 30, 50, 70 and 90 Hz in 80 healthy children aged 1 month to 6 years and in 21 adults. As repetition rate was increased from 10 to 90 Hz at 70 dB HL, the amplitudes in different age groups decreased by 33-45% (0.109-179 microV) for wave I and 25-41% (0.055-0.145 microV) for wave V. The older the children, the larger the absolute decrements of wave amplitudes with increasing repetition rate, but the relative decrements or reduction rates of wave amplitudes exhibited no systematically age-related differences. The V/I amplitude ratio tended to increase with increasing repetition rate in most age groups, suggesting that the amplitude of wave I is affected by the repetition rate slightly more than that of wave V. The patterns of the changes in wave amplitudes with repetition rate at lower intensity levels were essentially similar.

Acoustic Stimulation↗

PubMed1991

Intensity effect on amplitude of auditory brainstem responses in human.

Click intensity effect (90 to 0 dB HL) on amplitude of the auditory brainstem responses (ABAR) was studied in 152 normal children from birth to 6 years and 16 adults. All age groups showed similar amplitude-intensity functions for waves I and V. Wave I amplitude exhibited a 'transitional' response at 60 dB HL intensity, whereas wave V exhibited a more gradual change. As the clicks were decreased from 90 to 60 dB HL, amplitude reduction was much more dramatic for wave I (mean 57%) than for wave V (mean 30%), and the V/I amplitude ratio more than doubled (mean 70%). At moderate intensity range, the reduction in amplitude with the decrease in intensity is only slightly more for wave I than for wave V, and the V/I ratio continued to increase, but more slowly. Wave V amplitude changed linearly with click intensity at the rate of 0.024-0.042 microV/dB for different age groups. The older the children, the larger the decrement of wave V amplitude with decreasing intensity, which was accompanied by an age-related difference in the absolute amplitude at equal click intensities. The V/I amplitude ratio increased with decreasing intensity at a rate of about 0.01/dB, showing no apparent age-related difference.

Acoustic Stimulation↗

PubMed1990

Early development of brainstem auditory evoked potentials in Down's syndrome.

Early development of brainstem auditory pathway was studied in 14 children with Down's syndrome (age range from 1 month to 3 years). The brainstem auditory evoked potentials (BAEP) during infancy was characterized by elevated threshold and poorly differentiated wave I. All children within 2 years had elevated threshold in one or both ears, suggesting a high incidence of peripheral hearing deficits. Follow-up tests showed that as age increased up to 3 years the elevated threshold gradually decreased and the differentiation of wave I improved. The I-V interpeak interval was slightly shorter and the amplitude of wave V was smaller than the normal controls, which existed continuously during follow-up studies. Our findings suggest that the development of peripheral hearing is delayed, although persistent hearing deficits cannot be excluded, and the functioning and development of the brainstem auditory pathway may also be abnormal in Down's syndrome children.

Aging↗

PubMed1990

Long-term impairments of brain and auditory functions of children recovered from purulent meningitis.

Sixty children who had recovered from purulent meningitis one to six years earlier were investigated for long-term impairment of brain and auditory function, using brainstem auditory evoked potentials(BAEP) and developmental screening tests. Neurological and/or audiological BAEP abnormalities were found in 23 per cent of the children: 15 per cent had mild brainstem impairment and 12 per cent had hearing dysfunction. Developmental screening tests were administered to 46 children, of whom 61 per cent had normal, 22 per cent questionable and 17 per cent abnormal results. The results of the BAEP significantly correlated with those of the developmental screening tests, suggesting that the neuropsychological development of children with BAEP abnormalities was significantly delayed compared with that of children without BAEP abnormalities. The characteristic finding in a neurologically abnormal BAEP was slightly depressed amplitude of wave V, and the authors suggest that this is the most sensitive BAEP measure for the assessment of brainstem function in children recovered from meningitis.

Acoustic Stimulation↗

PubMed1989

Three new and bioactive icosanoids from the temperate red marine alga Farlowia mollis.

Three new dihydroxyicosanoids, 12(R),13(R)-dihydroxyicosa-5(Z),8(Z),10(E),14(Z)-tetraenoic acid, 12(R),13(R)-dihydroxyicosa-5(Z),8(Z),10(E),14(Z),17(Z)-pentaeno ic acid and 10(R*),11(R*)-dihydroxyoctadeca-6(Z),8(E),12(Z)-trienoic acid, have been isolated from a previously unstudied temperate red marine alga, Farlowia mollis (Cryptonemiales, Rhodophyta). The structures of these new metabolites have been deduced from detailed nuclear magnetic resonance and mass spectrometry analyses on stabilized diacetate-methyl esters and stereochemistry deduced by 1H NMR couplings and CD analysis of a dibenzoate derivative. Collectively, these new natural products modulate fMLP-induced superoxide anion generation in human neutrophils, inhibit the conversion of arachidonic acid to lipoxygenase products by human neutrophils, and inhibit the functioning of the dog kidney Na+/K+ ATPase.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗