Biomedical subjects

Z D Jiang

Publications and source records attributed to Z D Jiang.

At least 37 records · Page 2Linked to original sources

PubMed1999

Combined carotid endarterectomy and coronary artery bypass: immediate and long-term results.

Data from 213 cases of simultaneous carotid endarterectomy and coronary artery bypass grafting (CEN/CABG) were analyzed (1980-1996). There were 154 males (72.3%), and 59 females (27.7%), (mean age: 65. 6 years, range: 42-83). One hundred and thirty-two patients (62.0%) had angina, 58 (37.2%) had myocardial infarction, and 23 (10.8%) had congestive heart failure. Symptomatic cerebrovascular disease was present in 89 patients (41.7%). One hundred and twenty-two patients (57.2%) had three-vessel coronary artery disease, 41 (19.2%) had left main disease, and 27 (12.6%) had a low ejection fraction (ejection fraction </=30%). Significant (>/=75% diameter reduction) stenosis was present in 168 (78.8%) of the operated carotid arteries. The contralateral internal carotid artery was severely stenosed or occluded in 35 patients (16.4%). The hospital mortality rate was 5. 6% (12 patients). The cause of death was cardiac in ten patients (4. 6%), and neurologic in two (1%). Eleven patients (5.1%) developed a stroke postoperatively; eight strokes were ipsilateral to the operated artery, and six were permanent. Myocardial infarction occurred in five patients (2.3%). Independent predictors of early mortality were age >62 years, hypertension, and postoperative stroke (p < 0.05). Male sex was the only independent predictor of neurologic morbidity (p < 0.05). Late follow-up data were obtained for 163 (81.0%) patients (mean: 54.8 months, range: 1-168). Four (9. 3%) out of the 43 late deaths were attributed to strokes. There were three (1.8%) late ipsilateral strokes, and five (3.1%) contralateral strokes. The 5- and 10-year survival probabilities were 75 +/- 4%, and 52 +/- 6.9%. The freedom from late ipsilateral neurologic morbidity at 5 and 10 years were 97 +/- 1.7% and 90 +/- 4.0%, respectively. Taken together, the results indicate that combined carotid endarterectomy and coronary artery bypass grafting can be performed safely in this high-risk group of patients. Excellent long-term freedom from stroke can be expected.

Aged↗

PubMed1999

Improved detection of enterotoxigenic Escherichia coli among patients with travelers' diarrhea, by use of the polymerase chain reaction technique.

This study sought to determine whether a specific polymerase chain reaction (PCR) for enterotoxigenic Escherichia coli (ETEC) toxins after chaotropic extraction of DNA from stool would increase the detection of ETEC over that of conventional oligonucleotide probe hybridization of 5 E. coli colonies per stool sample (a standard method). By DNA hybridization, 29 (21%) of 140 patients were positive for ETEC, and 59 (42%) of 140 were positive for ETEC when PCR was used. Sensitivity of the PCR assay was confirmed through spiked stool experiments to be approximately 100-1000 ETEC colonies per sample. Specificity of the assay was determined by showing an absence of ETEC by the PCR technique in a subgroup of 48 subjects and by confirming the presence of ETEC DNA of positive samples by dot blot procedure. PCR technique detected significantly more ETEC infections in these subjects than did the hybridization method (P<.0001).

Bacterial Toxins↗

PubMed1999

Enteroaggregative Escherichia coli as a cause of traveler's diarrhea: clinical response to ciprofloxacin.

The purpose of this study was to determine the role of enteroaggregative Escherichia coli (EAEC) in the development of traveler's diarrhea and the clinical response of patients with EAEC diarrhea following treatment with ciprofloxacin. Sixty-four travelers with diarrhea and no other recognized enteropathogen were enrolled in treatment studies in Jamaica and Mexico from July 1997 to July 1998. EAEC was isolated from 29 travelers (45.3%). There was a significant reduction in the duration of posttreatment diarrhea in the 16 patients treated with ciprofloxacin, as compared with that in the 13 patients who received placebo (mean of 35.3 versus 55.5 hours; P = .049). There was a nonsignificant reduction in the mean number of unformed stools passed during the 72 hours after enrollment in the ciprofloxacin-treated group (5.6), as compared with that in the placebo group (7.5) (P = .128). This study provides additional evidence that EAEC should be considered as a cause of antibiotic-responsive traveler's diarrhea.

Adult↗

PubMed1999

Etiology of outpatient pediatric nondysenteric diarrhea: a multicenter study in the United States.

BACKGROUND: Few data have been published recently on the etiology of outpatient pediatric diarrhea in the US. METHODS: We determined the etiology of acute, nondysenteric diarrhea among 147 children between 2 and 11 years old presenting to 9 outpatient clinics in various regions of the US between August, 1991, and August, 1993. Enteropathogens were sought by conventional laboratory methods. The various diarrheagenic Escherichia coli were sought. RESULTS: A recognized etiologic agent was detected in the stools of 89 (60.5%) children and 15 (10) patients had multiple agents detected. Rotavirus was found in 43 (29.3%) of the children, with a spring and winter peak in occurrence. Giardia lamblia was identified in 22 (15%) cases with a spring peak. HEp-2 cell-adherent E. coli were found in 15 (10.2%). Other agents found included: enteric adenovirus in 7 (4.8%); Salmonella in 5 (3.4%); enterohemorrhagic E. coli in 5 (3.4%); enteropathogenic E. coli in 2 (1.4%); enterotoxigenic E. coli in 2 (1.4%); Entamoeba histolytica in 1 (0.70%); and Campylobacter jejuni in 1 (0.7%). CONCLUSIONS: In addition to the presence of conventional enteropathogens, diarrheagenic E. coli (HEp-2 cell-adherent E. coli, enterohemorrhagic E. coli, enteropathogenic E. coli and enterotoxigenic E. coli) were associated with endemic pediatric diarrhea in the US.

Acute Disease↗

PubMed1999

Brainstem auditory evoked response recorded using maximum length sequences in term neonates.

Brainstem auditory evoked response (BAER) was studied in term neonates using maximum length sequences (MLS), which allows presentation of acoustic stimuli at much higher rate than possible with conventional averaging technique. The response waveforms, especially for waves III and V, were well defined at the click rates of 91-455/s. Wave latencies and interpeak intervals at various click rates were all significantly longer and wave V amplitude was smaller in the neonates than in the adults. As click rate was increased, wave latencies increased and amplitudes progressively reduced. The slopes of wave latency-rate functions were progressively steeper for the later waves. The slopes of both III-V and I-V interval-rate functions were significantly steeper in the neonates than in the adults, indicating greater rate-dependent changes in the central components of the neonatal MLS BAER. These rate-dependent changes in the neonatal MLS BAER are generally similar to those in neonatal conventional BAER, although there are some differences. The results indicate that the neonatal brainstem can process rapid acoustic stimulation up to 455/s, although this ability remains immature.

Adult↗

PubMed1999

Outcome of brain stem auditory electrophysiology in children who survive purulent meningitis.

Brain stem auditory electrophysiology was assessed in children long after purulent meningitis by examining the central components of brain stem auditory evoked response (BAER) at different presentation rates of clicks. Children with peripheral hearing loss were excluded from this study to avoid any possible influence of the loss on the measurements of BAER central components. Of the 70 children who had recovered from meningitis 2 to 8 years earlier, 9 (12.9%) showed abnormalities in BAER central components--mainly a slight reduction of wave V amplitude, at the click presentation rate of 10/s. Of the remaining 61 children who did not show any obvious abnormalities in the BAER at 10/s, an abnormally prolonged I-V interval and a reduced amplitude of wave V were seen in 5 children (8.2%) at the click rate of 90/s. The total BAER abnormality rate was therefore 20.0% (14/70 cases). The results suggest that most children who survive purulent meningitis have a favorable outcome for the brain stem auditory pathway, with about 1 in 5 having mild dysfunction or a suboptimal outcome in the pathway.

Child, Preschool↗

PubMed1998

Auditory brainstem projections to the ferret superior colliculus: anatomical contribution to the neural coding of sound azimuth.

The mammalian superior colliculus (SC) contains a neural map of auditory space. It is not known whether this topographic representation emerges at the level of the SC or is relayed there from other auditory areas. We have used retrograde labelling techniques in ferrets to examine the sources and pattern of innervation from auditory brainstem nuclei. After multiple injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the SC, the heaviest concentrations of labelled cells were found in the nucleus of the brachium (BIN) and external nucleus of the inferior colliculus, with much weaker labelling in the nucleus sagulum, dorsal, intermediate and ventral nuclei of the lateral lemniscus, paralemniscal regions, and periolivary nuclei. The projections were predominantly ipsilateral, although labelled cells were found on both sides of the brainstem. Single injections of WGA-HRP or discrete injections of red and green latex microspheres revealed that the caudal and lateral regions of the SC receive the heaviest projections, although the majority of the retrogradely labelled neurons in the contralateral BIN project to rostral SC. On the ipsilateral side, neurons in rostral and caudal regions of the BIN were labelled primarily by the tracer injected into rostral and caudal regions of the SC, respectively. However, no clear segregation was apparent in the BIN after injections into the medial and lateral regions or in any of the other nuclei after either injection paradigm. These data suggest that converging inputs from several auditory brainstem nuclei contribute to the construction of the auditory space map in the SC, although information about sound azimuth may be conveyed to this nucleus via a spatially ordered projection from the ipsilateral BIN.

Animals↗

PubMed1998

Immaturity of electrophysiological response of the neonatal auditory brainstem to high repetition rates of click stimulation.

Changes in brainstem auditory evoked response (BAER) with varying stimulus repetition primarily represent neural processes concerning the efficacy of synaptic transmission in the brainstem auditory pathway. In this study the BAER to different rates of clicks was recorded from 16 term neonates. The results were compared with those from 16 adults to examine whether the degree of maturation of synaptic transmission of the neonatal brainstem auditory pathway parallels that of general function of the pathway. All BAER wave latencies and interpeak intervals increased linearly and wave amplitudes reduced with increasing click rate. The absolute rate-dependent changes in BAER measures were much greater in the neonates than in the adults, reflecting a significant immaturity in the efficacy of synaptic transmission in the neonatal auditory brainstem and in the ability of the neonatal brainstem to process rapid acoustic stimulation. When the data obtained at higher click rates at various age groups were analyzed as percentages, using the BAER measurements at conventionally used slow rate (21/s) of clicks as the denominators, the changing rates (%), or relative changes, of most BAER measures at higher rates in the neonates were still greater than those in the adults. Therefore, the rate-dependent BAER changes in the neonates are relatively less mature than general aspects of the BAER, reflected by the BAER elicited with conventionally used slow rates of clicks. These findings suggest that synaptic efficacy in the neonatal brainstem auditory pathway is relatively less mature than general function of the pathway and thus may be more susceptible to unfavourable perinatal conditions.

Acoustic Stimulation↗

PubMed1998

Maturation of peripheral and brainstem auditory function in the first year following perinatal asphyxia: a longitudinal study.

Maturation of peripheral hearing and auditory brainstem following perinatal asphyxia was investigated by longitudinal recording of brainstem auditory evoked potentials (BAEP) during the first year of life in affected infants. The general maturational course of the BAEP following asphyxia was similar to that in a control group of infants with normal births, although there were some abnormalities in the BAEP Response threshold elevation seen in a few asphyxiated infants improved significantly during the first 3 months. The interpeak intervals in the asphyxiated infants did not differ significantly from that of the control-group infants except in the first month, when the I-V and III-V intervals were significantly prolonged in the severe asphyxia group. In contrast, wave V amplitude and V/I ratio were always smaller when compared to that of the control-group infants. Amplitude reduction of wave V was more sustained than the prolonged I-V interval. Persistent hearing loss and brainstem auditory impairment were seen in 6.8% and 14.6% of the asphyxiated infants, respectively. These findings suggest that asphyxia does not interfere significantly with the maturation of the auditory system in most asphyxiated infants and that sustained peripheral hearing loss and brainstem impairment occur only in a small proportion of affected infants.

Age Factors↗

PubMed1998

HEp-2 cell-adherent Escherichia coli and intestinal secretory immune response to human immunodeficiency virus (HIV) in outpatients with HIV-associated diarrhea.

HEp-2 cell-adherent Escherichia coli and the human immunodeficiency virus (HIV) itself have recently been incriminated as causes of chronic HIV-associated diarrhea. This study sought to determine the prevalence of these two agents among HIV-infected patients with diarrhea in an outpatient setting in the United States and to compare their prevalence to that of other commonly recognized enteropathogens known to be present in this population. HEp-2 cell-adherent E. coli was found in 20 of 83 (24.1%) patients with diarrhea. A diffuse pattern of adherence was the most common, found in 14 of 20 (70%) patients, followed by a localized adherence pattern (6 of 20; 30%). An intestinal secretory immune response against the p24 antigen of HIV was found in 9 of 34 (27.5%) patients with HIV-associated diarrhea. The following pathogens or products were also detected in lower frequencies: Cryptosporidium spp. (10.8%), Clostridium difficile toxin (8.8%), microsporidia (6%), Isospora belli (3.6%), Blastocystis hominis (2.4%), Giardia spp. (1.2%), Salmonella spp. (1.2%), and Mycobacterium spp. (1.2%). The role of HEp-2 cell-adherent E. coli and HIV enteric infections in patients with HIV-associated diarrhea deserves further study.

Bacterial Adhesion↗

PubMed1998

Screening systems for detecting inhibitors of cell wall transglycosylation in Enterococcus. Cell wall transglycosylation inhibitors in Enterococcus.

We devised two screening systems to detect cell wall transglycosylation inhibitors. One screen utilizes a mutant of Enterococcus faecalis strain A256 that is dependent on vancomycin or moenomycin for growth. In the absence of transglycosylation inhibitors the strain fails to grow, while in the presence of inhibitors, cells are rescued. A second screening organism E. faecalis strain MDD212 utilizes a translational fusion of the lacZ gene to the vanH promoter in a derivative of E. faecalis that contains a vancomycin resistance determinant. Induction of beta-galactosidase occurs when cells are exposed to inhibitors of transglycosylation. Our natural products drug source of fungal fermentations was tested with these screens. Several cultures that produced the same family of compounds, called the thielavins, were detected. Thielavin B inhibited the formation of peptidoglycan in an in vitro assay, suggesting that these screening systems can detect compounds that interfere with cell wall transglycosylation.

Base Sequence↗

PubMed1997

Sources of subcortical projections to the superior colliculus in the ferret.

We have identified brainstem and other subcortical afferents to the superior colliculus (SC) in the ferret, by examining the pattern of retrograde labelling that resulted from unilateral injections of red and green fluorescent latex microspheres or of wheat germ agglutinin conjugated to horseradish peroxidase into different regions of this midbrain nucleus. Labelled neurons were found in many structures, including somatosensory, visual and auditory nuclei. These subcortical inputs are almost all bilateral, although most are primarily ipsilateral. Despite some differences in organization, the subcortical projections to the ferret SC broadly resemble those described in other species. Following injections of red and green microspheres in either the rostral and caudal or the medial and lateral regions of the SC, double-labelled cells usually accounted for less than 10% of the total number of retrogradely labelled cells, indicating that most of the subcortical neurons project to discrete regions of the SC. Many of these afferents show some topographic organization, which is much more evident along the rostrocaudal axis of the SC than in the medial-lateral dimension. The intercollicular projection is restricted mainly to the rostral SC and demonstrates a point-to-point organization. Most of the subcortical structures caudal to the central region of the SC were labelled mainly by the tracers injected in caudal SC, while those rostral to this region, including the zona incerta and the pretectal nuclei, were labelled largely by injections in rostral SC. These findings suggest that projections originating from nuclei posterior to the central region of the SC terminate principally in caudal SC whereas afferents from structures anterior to the central region project largely to rostral SC.

Afferent Pathways↗

PubMed1997

Novel oxylipins from the temperate red alga Polyneura latissima: evidence for an arachidonate 9(S)-lipoxygenase.

The oxylipin chemistry of the temperate red alga Polyneura latissima has been investigated. The structures of three novel oxylipins, 8-[1'(Z),3'(Z),6'(Z)-dodecatriene-1'-oxy]- 5(Z),7(E)-octadienoic acid, 7(S*)-hydroxy-8(S*),9(S*)-epoxy-5(Z),11(Z),14(Z)-eicosatrienoic acid, 7(R*)-hydroxy-8(S*),9(S*)-epoxy-5(Z),11(Z),14(Z)-eicosatrienoic acid, together with two known eicosanoids, 9(S)-hydroxy-5(Z),7(E),11(Z),14(Z)-eicosatetraenoic acid, and 9,15-dihydroxy-5(Z),7(E),11(Z),13(E)-eicosatetraenoic acid, were elucidated by spectroscopic methods and chemical degradation. The oxygenation pattern of these oxylipins suggests that P. latissima metabolizes polyunsaturated fatty acids via a 9(S)-lipoxygenase.

Arachidonate Lipoxygenases↗

PubMed1997

Continuous electroencephalographic monitoring and selective shunting reduces neurologic morbidity rates in carotid endarterectomy.

PURPOSE: The role of continuous electroencephalographic (EEG) monitoring during carotid endarterectomy was evaluated in this retrospective review. METHODS: We analyzed data from 902 consecutive carotid endarterectomy procedures performed with vein patch angioplasty. In 591 operations from 1980 to 1988 we did not use intraoperative EEG monitoring or shunting (non-EEG group). Continuous intraoperative EEG monitoring and selective shunting were used in 311 procedures from 1988 to 1994 (EEG group). The patients' mean age was higher in the EEG group (68.8 years; range, 41 to 87 years) than in the non-EEG group (66.2 years; range, 34 to 90 years; p < 0.001). There was also a significantly higher incidence of hypertension (56.2% vs 41.9%) and redo operations (5.4% vs 2.54%) in the EEG group than in the non-EEG group (p < 0.05). The operative technique was identical in both groups. We defined a significant EEG change as a greater than 50% reduction of the amplitude of the faster frequencies, a persistent increase of delta activity, or both. RESULTS: In the EEG group, acute EEG changes occurred in 40 patients (12.8%); 31 (77.5%) unilateral and ipsilateral to the operated carotid artery, and nine (22.5%) bilateral. In five patients (12.5%) the changes correlated with an intraoperative episode of hypotension, and after normal blood pressure was restored the EEG returned to normal. In 35 procedures (87.5%) a carotid shunt was inserted. In 33 of those patients the EEG returned to baseline, in one patient there was a significant improvement, and in one patient the EEG changes persisted. Postoperative hospital strokes occurred in one patient (0.32%) in the EEG group and in 13 patients (2.19%) in the non-EEG group (p < 0.05). All strokes (n = 14) were ipsilateral to the operated carotid artery. Of the 13 strokes in the non-EEG group nine were major and four were minor. The one stroke in the EEG group was embolic in origin and occurred before carotid cross-clamping; it was associated with profound EEG changes that did not reverse after placement of a shunt. In the total group (n = 902), intraoperative EEG monitoring was inversely associated with postoperative stroke (p < 0.05). CONCLUSION: The overall neurologic morbidity rate was significantly lower in the EEG group than in the non-EEG group, therapy demonstrating the value of intraoperative EEG monitoring in carotid endarterectomy.

Adult↗

PubMed1996

Topographic organization of projection from the parabigeminal nucleus to the superior colliculus in the ferret revealed with fluorescent latex microspheres.

Unilateral, discrete injections of red and green fluorescent latex microspheres or injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) were made into the ferret's superior colliculus (SC) to characterize the topographic organization of the projection from the parabigeminal nucleus (PBN). Retrograde labelling in the PBN revealed that this nucleus projects bilaterally to the SC, although the heaviest projection arises from the ipsilateral PBN. The PBN-SC projection demonstrates a highly ordered organization along the rostral-caudal axis; rostral PBN projects to rostral SC and caudal PBN projects to caudal SC. The caudoventral and rostrodorsal areas of the PBN project mainly to the ipsilateral and contralateral SC, respectively. The ipsilateral pathway terminates principally in the caudal region of the SC, while the contralateral projection terminates predominantly in rostral SC. Ipsilaterally, there are slightly more neurons, located mainly in the ventral PBN, that project to the lateral SC than those, located largely in the dorsal part of the nucleus, that target the medial SC. The contralateral PBN mainly projects to the rostrolateral quadrant of the SC. These results indicate that each quadrant of the SC is innervated principally by a restricted part of the PBN: the caudolateral quadrant, which receives the heaviest ipsilateral input, and the caudomedial quadrant are targeted predominantly by the ventral and dorsal portions, respectively, of the ipsilateral PBN; the rostrolateral quadrant by the contralateral PBN, and the rostromedial quadrant, which receives the weakest input, by the dorsal portion of the nucleus on both sides. These findings suggest that activity in the PBN is relayed to distinct regions of the SC in the form of a highly ordered topographic projection. The adjacent lateral tegmentum (ALT) also projects heavily to the SC, principally on the ipsilateral side. The ALT projection to the ipsilateral SC appears to be organized in a less orderly fashion, and terminates principally in caudal SC, particularly the caudolateral quadrant. No topography was apparent for the contralateral projection.

Animals↗

PubMed1996

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

Long-term effect of perinatal and postnatal asphyxia on the developing auditory brainstem was investigated in children, particularly those who exhibited residual neurodevelopmental deficits, by analyzing the central components of brainstem auditory evoked responses (BAER). The major abnormalities in the BAER were a reduction of wave V amplitude, followed by a decrease in V/I amplitude ratio, while abnormalities in interpeak intervals were relatively rare. These findings suggest that asphyxia could result in residual neural dysfunction of the brainstem but does not appear to exert any major long-term effect on neuronal transmission. BAER abnormalities occurred more frequently in the children with residual neurodevelopmental deficits than those without these deficits after perinatal asphyxia. The occurrence of BAER abnormalities was related to the duration as well as the degree of asphyxia. No significant difference was found in the abnormalities of the central BAER components between the children after perinatal asphyxia and those after postnatal asphyxia, suggesting that perinatal and postnatal asphyxia exerts a similar long-term effect on the developing central nervous system.

Asphyxia Neonatorum↗

PubMed1996

Binaural interaction and the effects of stimulus intensity and repetition rate in human auditory brain-stem.

Binaural interaction (BI) components in brain-stem auditory evoked potential (BAEP) and their changes with stimulus intensity and repetition rate were examined in human adult. Seven BI components were identified, which occurred between the latency range of 5 and 11 ms and coincided consistently with the latency range of BAEP waves IV-VII. Waves DV and DVII, occurring at the downslopes of BAEP waves V and VII, respectively, were the two most prominent and reproducible BI components. Wave DVII existed consistently at high, moderate and, in most cases, low stimulus intensities, suggesting that this component is neurogenic although acoustic cross-talk may account for a part of its waveform at high stimulus intensities. The latencies of all BI components increased as a function of decreasing stimulus intensity, while the interpeak intervals, especially DV-DVII, were essentially constant at different intensity levels. The amplitudes of BI components decreased slightly with decreasing intensity. As click repetition rate increased, BI wave latencies and interpeak intervals increased slightly and amplitudes decreased slightly. When repetition rate increased to above 20/s, BI components became poorly differentiated. Lower repetition rates, e.g. 10/s, are therefore preferred for routine derivation of the BI. The changes in the latency and amplitude of BI components with stimulus intensity and repetition rate were associated or concomitant with those of the corresponding BAEP components in monaural and binaural potentials. In view of the concomitant relationship between BI and BAEP latency, we designate BI components in association with the corresponding BAEP components.

Acoustic Stimulation↗

PubMed1996

Binaural interaction in human neonatal auditory brainstem.

Binaural interaction (BI) in brainstem auditory evoked response (BAER) were examined in normal term neonates. The BI components coincided consistently with the latency range of BAER wave IV through wave VII. Most BI components seen in the adults could be identified in the neonates, but the later components, i.e. those with longer latency, were underdeveloped in wave form. Wave DV was the most consistent and reproducible BI component. A marked difference between the neonatal and adult BI wave forms was that wave DVII was particularly small in the neonates. It appears that neuronal responses contributing to later BI components such as wave DVII are particularly immature at birth. Wave latencies and interpeak intervals were longer and amplitudes were smaller in the neonates than in the adults, which was associated with the differences between the neonates and adults in the BAER components. Changes in the BI components with stimulus intensity and rate in the neonates were fundamentally similar to but more significant compared with those in the adults. These findings suggest that neural connections in human auditory brainstem subserving the BI are established at birth but, particularly at higher levels of the brainstem, are immature.

Acoustic Stimulation↗