[Management and short-term outcomes of neonates born to mothers infected with SARS-CoV-2 Omicron variant]

Objective: To summarize the management and short-term outcomes of neonates delivered by mothers infected with SARS-CoV-2 Omicron variant. Methods: A retrospective study was performed on 158 neonates born to mothers infected with SARS-CoV-2 Omicron variant admitted to the isolation ward of Children's Hospital of Fudan University from March 15^th, 2022 to May 30^th, 2022. The postnatal infection control measures for these neonates, and their clinical characteristics and short-term outcomes were analyzed. They were divided into maternal symptomatic group and maternal asymptomatic group according to whether their mothers had SARS-CoV-2 symptoms. The clinical outcomes were compared between the 2 groups using Rank sum test and Chi-square test. Results: All neonates were under strict infection control measures at birth and after birth. Of the 158 neonates, 75 (47.5%) were male. The gestational age was (38⁺³±1⁺³) weeks and the birth weight was (3 201±463)g. Of the neonates included, ten were preterm (6.3%) and the minimum gestational age was 30⁺¹ weeks. Six neonates (3.8%) had respiratory difficulty and 4 of them were premature and required mechanical ventilation. All 158 neonates were tested negative for SARS-COV-2 nucleic acid by daily nasal swabs for the first 7 days. A total of 156 mothers (2 cases of twin pregnancy) infected with SARS-CoV-2 Omicron variant, the time from confirmed SARS-CoV-2 infection to delivery was 7 (3, 12) days. Among them, 88 cases (56.4%) showed clinical symptoms, but none needed intensive care treatment. The peripheral white blood cell count of the neonates in maternal symptomatic group was significantly higher than that in maternal symptomatic group (23.0 (18.7, 28.0) × 10⁹ vs. 19.6 (15.4, 36.6) × 10⁹/L, Z=2.44, P<0.05). Conclusions: Neonates of mothers infected with SARS-CoV-2 Omicron variant during third trimester have benign short-term outcomes, without intrauterine infection through vertical transmission. Strict infection control measures at birth and after birth can effectively protect these neonates from SARS-CoV-2 infection.

[Diagnostic value of rapid antigen testing for the detection of SARS-CoV-2 infection]

Objective: To investigate the diagnostic value of rapid antigen test based on colloidal gold immunochromatographic assay for the detection of SARS-CoV-2 infection in symptomatic patients. Methods: From May 20 to June 5 2022, 76 hospitalized children and their 55 accompanying family members with confirmed SARS-CoV-2 infection in the COVID-19 isolation unit of the Children's Hospital of Fudan University (designated referral hospital for SARS-CoV-2 infection in Shanghai) enrolled. Their nasopharyngeal swab specimens were consecutively collected. The samples were tested for SARS-CoV-2 nucleic acid by real-time quantitative. SARS-CoV-2 antigen was tested by immunochromatography. The correlation between the antigen detection results and the change of the cycle threshold (Ct) values were evaluated, as well as the sensitivity and specificity of SARS-CoV-2 antigen detection at different periods after the onset of the disease. Kappa consistency test was conducted to investigate the consistency between the 2 diagnostic methods. Results: Of the enrolled SARS-CoV-2 symptomatic infections, 76 were children, including 41 males and 35 females, with an age of 5 (2, 9) years; 55 were accompanying families, including 8 males and 47 females, with an age of 38 (32, 41) years. All 478 samples were simultaneously tested for SARS-CoV-2 antigen and nucleic acid. In any period from disease onset to negative conversion of viral nucleic acid, the overall sensitivity of the rapid antigen test was 48.2% (119/247), the specificity was 98.3% (227/231), and antigen test and nucleic acid test showed moderate consistency (κ=0.46, P<0.05). The sensitivity of antigen test was 100% (82/82) when the Ct value was ≤25. And the sensitivity of antigen test was 8/10, 4/15 and 8.3% (3/36) when the Ct value was 26, 30 and 35, respectively. All antigen tests were negative when Ct value was >35. During the period of 1-2 days, 3-5 days, 6-7 days, 8-10 days and >10 days after onset, the sensitivity and specificity of SARS-CoV-2 antigen test were 5/8 and 5/5, 90.2% (37/41) and 5/5, 88.9% (24/27) and 2/5, 45.0% (36/80) and 94.1% (32/34), 18.7% (17/91) and 98.9% (183/185) respectively. The Ct values of nasopharyngeal swabs were<26 during 2 to 7 days after onset, 28.7±5.0 on day 8, 34.5±2.9 on day 13 and > 35 after 14 days, respectively. Conclusion: SARS-CoV-2 antigen test in the patients with SARS-CoV-2 infection shows acceptable sensitivity and specificity within 7 days after onset of disease, and the sensitivity was positively correlated with viral load and negatively correlated with onset time.

[Mechanical analysis of the impact of the morphology of the iris and ciliary body on the central vault after posterior chamber phakic intraocular lens implantation]

Objective: To investigate the impact of the iris and ciliary body morphology on the central vault after phakic posterior chamber intraocular lens (pIOL) implantation. Methods: This research was based on the retrospective analysis of 123 patients (123 eyes) who underwent pIOL implantation in the Department of Ophthalmology, Affiliated Hospital of Qingdao University between June 2018 and June 2020. The anterior segment structure was observed with an ultrasound biomicroscope before surgery, and all morphological parameters of the iris and ciliary body were measured manually using the ImageJ software, including iris span (IS), iris convexity (IC), iris-ciliary body contact distance (ICCD) and iris-lens contact distance (ILCD). The ICCD was divided into Q1, Q2 and Q3 groups according to the equidistant distance of 0.36 mm. The lens thickness was measured with the IOLMaster. The horizontal corneal diameter and anterior chamber depth were measured using the Pentacam. The central vaults were measured by optical coherence tomography at 1 week, 3 months and 1 year after surgery. The relationships between vault values and preoperative parameters of the anterior segment were evaluated using the Pearson correlation analysis, Spearman correlation analysis, and multiple linear regression. The repeated measures ANOVA was applied to identify changes of vault values over time. Results: The mean values of the vaults at 1 week, 3 months and 1 year after surgery were (723±265) μm, (642±255) μm and (613±280) μm, respectively. The difference among them was statistically significant (F=50.143, P<0.001). The vaults continued to decline within 1 year after pIOL implantation, and the total decline was (122±86) μm. The vaults declined by (69±98) μm from postoperative 1 week to 3 months and by (52±54) μm from postoperative 3 months to 1 year. The regression formula showed that the pIOL size and ILCD were positively related with the vault, while the LT, IS and IC were negatively related with the vault at 1 week postoperatively (adjusted R²=0.404, P<0.001). The pIOL size and ILCD were positively related with the vault, while the IS and IC were negatively related with the vault at 3 months postoperatively (adjusted R²=0.342, P<0.001). The pIOL size was positively related with the vault, while the IS and IC were negatively related with the vault at 1 year postoperatively (adjusted R²=0.661, P<0.001). The vault values were higher in group Q3 compared to group Q1 at every timepoint, and the vault value was higher in group Q2 compared to Q1 at 1 year postoperatively. Conclusions: In the early postoperative period, eyes with a larger pIOL, shorter iris span, longer contact distance between the iris and ciliary body, and longer contact distance between the iris and lens were associated with a higher rate of excessive vaults. Meanwhile, eyes with a thicker lens and larger iris reverse convexity were more likely to obtain insufficient vaults. Within one year after surgery, the pIOL size, IS, IC and ICCD continued to impact on the vault. The ICCD, ILCD and IC can reflect the posterior chamber volume and change the haptic location and force, thus affecting the vault.

[A nomogram for predicting lymph node metastasis in early gastric cancer]

Objective: To explore the independent risk factors of lymph node metastasis (LNM) in early gastric cancer, and to use nomogram to construct a prediction model for above LNM. Methods: A retrospective cohort study was conducted. Inclusion criteria: (1) primary early gastric cancer as stage pT1 confirmed by postoperative pathology; (2) complete clinicopathological data. Exclusion criteria: (1) patients with advanced gastric cancer, stump gastric cancer or history of gastrectomy; (2) early gastric cancer patients confirmed by pathology after neoadjuvant chemotherapy; (3) other types of gastric tumors, such as lymphoma, neuroendocrine tumor, stromal tumor, etc.; (4) primary tumors of other organs with gastric metastasis. According to the above criteria, 1633 patients with early gastric cancer who underwent radical gastrectomy at the Department of General Surgery of the Chinese PLA General Hospital First Medical Center from December 2005 to December 2020 were enrolled as training set, meanwhile 239 patients with early gastric cancer who underwent gastrectomy at the Department of General Surgery of the Chinese PLA General Hospital Fourth Medical Center from December 2015 to December 2020 were enrolled as external validation set. Risk factors of LNM in early gastric cancer were identified by using univariate and multivariate logistic regression analyses. A nomogram prediction model was established with significant factors screened by multivariate analysis. Area under the receiver operating characteristic curve (AUC) was used for assessing the predictive value of the model. Calibration curve was drawn for external validation. Results: Among 1633 patients in training set, the mean number of retrieved lymph nodes was 20 (13-28), and 209 patients (12.8%) had lymph node metastasis. Univariate analysis showed that gender, resection range, tumor location, tumor morphology, lymph node clearance, vascular invasion, lymphatic cancer thrombus, tumor length, tumor differentiation, microscopic presence of signet ring cells and depth of tumor invasion were associated with LNM (all P<0.05). Multivariate analysis revealed that females, tumor morphology as ulcer type, vascular invasion, lymphatic cancer thrombus, tumor length≥3 cm, deeper invasion of mucosa, and poor differentiation were independent risk factors for LNM in early gastric cancers (all P<0.05). Receiver operating characteristic curve indicated that AUC of training set was 0.818 (95%CI: 0.790-0.847) and AUC of external validation set was 0.765 (95%CI: 0.688-0.843). The calibration curve showed that the LNM probability predicted by nomogram was consistent with the actual situation (C-index: 0.818 in training set and 0.765 in external validation set). Conclusions: Females, tumor morphology as ulcer type, vascular invasion, lymphatic cancer thrombus, tumor length≥3 cm, deeper invasion of mucosa and poor differentiation are independent risk factors for LNM of early gastric cancer. The establishment of a nomogram prediction model for LNM in early gastric cancer has great diagnostic value and can provide reference for treatment selection.

[Analysis of influence factors for short-term recurrence of retroperitoneal liposarcoma after complete resection]

Objective: To examine the influence factors of short-term recurrence after complete surgical resection of retroperitoneal liposarcoma. Methods: The clinicopathological data of retroperitoneal liposarcoma at Department of General Surgery, the First Medical Center, People's Liberation Army General Hospital from January 1, 2000 to January 31, 2020 were retrospectively analyzed. There were 60 males and 31 females, aged (52.1±9.9) years (range: 30 to 84 years). Tumor recurrence within 12 months after complete resection was defined as short-term recurrence, and tumor recurrence more than 12 months was defined as non-short-term recurrence. The t test, rank-sum test, χ² test and Fisher exact test were conducted for inter-group comparison. Logistic regression analysis was used to analyze the independent influence factors for the short-term recurrence of retroperitoneal liposarcoma after complete resection. The Kaplan-Meier curve was used to calculate the recurrence-free survival, and the Log-rank test was adopted for the comparison between the groups. Results: The univariate analysis results showed that irregular tumor morphology, multiple pathological subtypes, pathological scores>3, and multiple primary tumors are influence factors for short-term recurrence after complete resection of retroperitoneal liposarcoma (χ²: 4.422 to 7.773, all P<0.05). Regression analysis of the above risk factors showed that multiple primary tumors was the independent risk factor (OR=2.918, 95%CI: 1.127 to 7.556, P=0.027). In the short-term recurrence group, Kaplan-Meier curve analysis showed that patients with multiple primary tumors had a shorter median recurrence time than patients with unifocal tumor (6 months vs. 9 months, P=0.028). Conclusions: Multiple primary tumor is an independent risk factor for short-term recurrence after complete resection of retroperitoneal liposarcoma. It suggests that the frequency of follow-up after surgery should be increased for such patients.

[Corneal nerve repair and optical density in patients with high myopia after three kinds of corneal refractive surgery]

Objective: To investigate the repair of subepithelial nerve fibers in different areas of the cornea and the difference of corneal transparency 12 months after small incision lenticule extraction (SMILE), femtosecond laser in situ keratomileusis (FS-LASIK) and excimer laser in situ keratomileusis (LASEK) in high myopia. Methods: A cohort study. From June 2018 to October 2019, 30 patients with high myopia (60 eyes) were selected for corneal refractive surgery in the Department of Ophthalmology, Affiliated Hospital of Qingdao University, including 16 females (32 eyes) and 14 males (28 eyes). According to the mode of operation, the patients were divided into the SMILE group (n=10), FS-LASIK group (n=11) and LASEK group (n=9). The repair of subepithelial nerves in different areas of the cornea was observed by laser confocal microscopy 12 months after operation,and the morphological parameters were analyzed by ACCMetrics software. The parameters included corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD), corneal nerve fiber length (CNFL), corneal nerve fiber total branch density (CTBD) and corneal nerve fiber width. The Pentacam anterior segment analyzer was used to measure the optical density of the cornea in different diameters. The nerve fiber parameters and corneal optical density were compared by random block analysis of variance, and multiple comparisons were performed between groups by the Turkey test. Results: Twelve months after operation, there was no significant difference in the CNFD among the three groups(all P>0.05). The CNBD around the upper corneal incision in the SMILE group, FS-LASIK group and LASEK group was (7.81±7.93), (9.61±7.18) and (21.25±15.55) branches/mm², respectively. The CTBD was (22.00±16.02), (24.44±11.42) and (54.37±22.13) branches/mm², respectively. The values in the LASEK group significantly differed from the other two groups (HSD=2.823, -3.010, 3.053, -3.048, P<0.01). The CNFL was (9.19±3.25), (12.88±3.52) and (15.75±2.36) mm/mm², respectively. The value in the SMILE group was significantly different (HSD=-3.151, -4.418; P<0.0l). The corneal optical density after SMILE was 13.16±0.72 in the 0-6 mm diameter area(HSD=-4.164, -4.489; P<0.01), 16.12±3.18 in the 6-12 mm diameter area(HSD=-3.918, -3.493;P<0.01) and 14.06±1.36 in the total diameter (HSD=-6.031, -5.519;P<0.01), which differed significantly from the other two groups. Conclusions: Twelve months after SMILE for high myopia, the nerve repair around the superior corneal incision is slightly worse than that after FS-LASIK and LASEK, but the nerve repair in other areas has some advantages, and the corneal transparency is better. (Chin J Ophthalmol, 2021, 57:268-276).

Occurrence, Human Exposure, and Risk Assessment of Polybrominated Dibenzo-p-Dioxins and Dibenzofurans, Polychlorinated Naphthalenes, and Metals in Atmosphere Around Industrial Parks in Jiangsu, China

Air samples were collected around industrial parks in Jiangsu, China, to allow the concentrations, profiles, and risk assessment of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), polychlorinated naphthalenes (PCNs), and metals to be investigated. The concentrations of ΣPBDD/Fs and ΣPCNs were 1324.26-2080.98 fg/m³ (11.35-42.57 fg I-TEQ/m³) and 10,404.9-29,322.9 fg/m³ (1.32-7.19 fg I-TEQ/ m³), respectively. The highest concentration of ΣPBDD/Fs and ΣPCNs were observed at site C. PBDD/Fs were mainly dominated by PBDFs. The main contributor to the ΣPBDD/Fs in all samples was 1,2,3,4,6,7,8-HpBDF, which accounted for 25.75%-39.4%. For PCNs, the predominating homologues were tetra-, tri- and penta-CNs, which contributed 30.7%-43.3%, 24.7%-31.0%, and 10.6%-21.6%, respectively. As for metals, the pollution of As, Mn, Cr, and Ni in most samples exceeded National Ambient Air Quality Standards of China. Assessing the risk of inhalation exposure showed that there were potential carcinogenic risks to local residents.

Concentrations, Sources, and Potential Human Health Risks of PCDD/Fs, dl-PCBs, and PAHs in Rural Atmosphere Around Chemical Plants in Jiangsu Province, China

Concentrations and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), and polycyclic aromatic hydrocarbons (PAHs) in a rural atmosphere near industrial zones in Jiangsu, China were determined and the associated risks were assessed. The concentrations of ΣPCDD/Fs, ΣPCBs, and ΣPAHs ranged from 11.9-57.7 pg·m^-3, 0.58-2.71 pg m^-3, and 11-18 ng m^-3, respectively. Principal component analysis suggested that the contamination of air with PCDD/Fs and PCBs mainly originated from industrial activities and combustion processes. In contrast, the major source of PAHs was the combustion of petroleum, coal, and biomass. These data were used to estimate the exposure of the population living nearby to these persistent organic pollutants and to evaluate the non-carcinogenic and carcinogenic risks associated with their inhalation. Our study are likely to be helpful for developing and implementing regulation strategies for PCDD/Fs, dl-PCBs, and PAHs in the atmosphere around industrial and surrounding residential areas.

Detection of serum procalcitonin and hypersensitive C-reactive protein in patients with pneumonia and sepsis

Sepsis, a systemic inflammatory response syndrome induced by infection, has high rates of morbidity and mortality. Pneumonia is a major cause for sepsis; however, pneumonia complicated by sepsis is a difficult clinical diagnosis. To assess the clinical relevance of serum procalcitonin (PCT) and hypersensitive C-reactive protein (hs-CRP) in early diagnosis of pneumonia complicated by sepsis, 220 patients with pneumonia who were admitted to hospital from July 2015 to July 2016 were enrolled in this study. The patients were divided into non-sepsis (N=82), mild sepsis (N=97), severe sepsis (N=23), and septic shock (N=18) groups. The patients were also divided into a survival group (N=186) and a death group (N=34) according to their prognosis at 2 weeks. The PCT and hs-CRP levels and Acute Physiology and Chronic Health Evaluation-II (APACHE-II) scores of the two groups were evaluated. The PCT level and APACHE-II score showed a progressively increasing tendency in the non-sepsis, mild sepsis, severe sepsis, and septic shock group; the differences between all pairs of groups were significant (P less than 0.05). The hs-CRP level was significantly lower in the non-sepsis group than in the other groups (P less than 0.05), but differences among the other groups were not significant (P>0.05). The areas under the receiver operating characteristic curves of PCT and hs-CRP for diagnosis of pneumonia complicated by mild and severe sepsis were 0.841 and 0.817, respectively. The optimal cut-off points for pneumonia and sepsis were ≥0.5 ng/mL and ≥55 mg/L, respectively; the sensitivity and specificity were 71.42% and 82.13%, and 75.04% and 53.61%, respectively. The sensitivity and specificity of diagnosis based on PCT and hs-CRP were 89.32% and 85.68%, respectively. PCT and hs-CRP are used to assess the severity of pneumonia in combination with sepsis in new-borns, but PCT is more strongly related to the severity of sepsis than is hs-CRP. Detection of PCT in combination with hs-CRP facilitates the early diagnosis of pneumonia and sepsis in new-borns, as well as monitoring of the treatment response and prediction of the prognosis.

[Research progress in metabolic and receptor-like nuclear imaging agents for hepatocellular carcinoma]

Hepatocellular carcinoma (HCC) commonly presents with high morbidity and mortality, and early staging diagnosis and timely treatment is pivotal to prolonging patients' survival time. Compared with traditional morphological imaging methods such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI), functional imaging methods like single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are playing an increasingly important role in the early diagnosis, efficacy assessment, prognostic evaluation, and treatment planning for HCC, thanks to their higher sensitivity at a molecular level by using various radiopharmaceuticals.

Slow binocular rivalry in bipolar disorder

BACKGROUND

The rate of binocular rivalry has been reported to be slower in subjects with bipolar disorder than in controls when tested with drifting, vertical and horizontal gratings of high spatial frequency.

METHOD

Here we assess the rate of binocular rivalry with stationary, vertical and horizontal gratings of low spatial frequency in 30 subjects with bipolar disorder, 30 age- and sex-matched controls, 18 subjects with schizophrenia and 18 subjects with major depression. Along with rivalry rate, the predominance of each of the rivaling images was assessed, as was the distribution of normalized rivalry intervals.

RESULTS

The bipolar group demonstrated significantly slower rivalry than the control, schizophrenia and major depression groups. The schizophrenia and major depression groups did not differ significantly from the control group. Predominance values did not differ according to diagnosis and the distribution of normalized rivalry intervals was well described by a gamma function in all groups.

CONCLUSIONS

The results provide further evidence that binocular rivalry is slow in bipolar disorder and demonstrate that rivalry predominance and the distribution of normalized rivalry intervals are not abnormal in bipolar disorder. It is also shown by comparison with previous work, that high strength stimuli more effectively distinguish bipolar from control subjects than low strength stimuli. The data on schizophrenia and major depression suggest the need for large-scale specificity trials. Further study is also required to assess genetic and pathophysiological factors as well as the potential effects of state, medication, and clinical and biological subtypes.

Functional development of the inferior colliculus (IC) and its relationship with the auditory brainstem response (ABR) in the tammar wallaby (Macropus eugenii)

To discover the developmental relationship between the auditory brainstem response (ABR) and the focal inferior colliculus (IC) response, 32 young tammar wallabies were used, by the application of simultaneous ABR and focal brainstem recordings, in response to acoustic clicks and tone bursts of seven frequencies. The IC of the tammar wallaby undergoes a rapid functional development from postnatal day (PND) 114 to 160. The earliest (PND 114) auditory evoked response was recorded from the rostral IC. With development, more caudal parts of the IC became functional until age about PND 127, when all parts of the IC were responsive to sound. Along a dorsoventral direction, the duration of the IC response decreased, the peak latency shortened, while the amplitude increased, reaching a maximum value at the central IC, then decreased. After PND 160, the best frequency (BF) of the ventral IC was the highest, with values between 12.5 and 16 kHz, the BF of the dorsal IC was the lowest, varying between 3.2 and 6.4 kHz, while the BF of the central IC was between 6.4 and 12.5 kHz. Between PND 114 and 125, the IC response did not have temporal correlation with the ABR. Between PND 140 and 160, only the early components of the responses from the ventral and central IC correlated with the P4 waves of the ABR. After PND 160, responses recorded from different depths of the IC had a temporal correlation with the ABR.

Temporal relationship between the auditory brainstem response and focal responses of auditory nerve root and cochlear nucleus during development in the tammar wallaby (Macropus eugenii)

Thirty-two pouch-young tammar wallabies were used to discover the generators of the auditory brainstem response (ABR) during development by the use of simultaneous ABR and focal brainstem recordings. A click response from the auditory nerve root (ANR) in the wallaby was recorded from postnatal day (PND) 101, when no central auditory station was functional, and coincided with the ABR, a simple positive wave. The response of the cochlear nucleus (CN) was detected from PND 110, when the ABR had developed 1 positive and 1 negative peak. The dominant component of the focal ANR response, the N1 wave, coincided with the first half of the ABR P wave, and that of the focal CN response, the N1 wave, coincided with the later two thirds. In older animals, the ANR response coincided with the ABR's N1 wave, while the CN response coincided with the ABR's P2, N2 and P3 waves, with its contribution to the ABR P2 dominant. The protracted development of the marsupial auditory system which facilitated these correlations makes the tammar wallaby a particularly suitable model.

Interhemispheric switching mediates perceptual rivalry

BACKGROUND

Binocular rivalry refers to the alternating perceptual states that occur when the images seen by the two eyes are too different to be fused into a single percept. Logothetis and colleagues have challenged suggestions that this phenomenon occurs early in the visual pathway. They have shown that, in alert monkeys, neurons in the primary visual cortex continue to respond to their preferred stimulus despite the monkey reporting its absence. Moreover, they found that neural activity higher in the visual pathway is highly correlated with the monkey's reported percept. These and other findings suggest that the neural substrate of binocular rivalry must involve high levels, perhaps the same levels involved in reversible figure alternations.

RESULTS

We present evidence that activation or disruption of a single hemisphere in human subjects affects the perceptual alternations of binocular rivalry. Unilateral caloric vestibular stimulation changed the ratio of time spent in each competing perceptual state. Transcranial magnetic stimulation applied to one hemisphere disrupted normal perceptual alternations when the stimulation was timed to occur at one phase of the perceptual switch, but not at the other. Furthermore, activation of a single hemisphere by caloric stimulation affected the perceptual alternations of a reversible figure, the Necker cube.

CONCLUSIONS

Our findings suggest that interhemispheric switching mediates perceptual rivalry. Thus, competition for awareness in both binocular rivalry and reversible figures occurs between, rather than within, each hemisphere. This interhemispheric switch hypothesis has implications for understanding the neural mechanisms of conscious experience and also has clinical relevance as the rate of both types of perceptual rivalry is slow in bipolar disorder (manic depression).

Rhenium-186-labeled hydroxyethylidene diphosphonate dosimetry and dosing guidelines for the palliation of skeletal metastases from androgen-independent prostate cancer

Rhenium-186 (tin)-labeled hydroxyethylidene diphosphonate (186Re-labeled HEDP) was evaluated in 27 men with progressive androgen-independent prostate cancer and bone metastases. Administered activities ranged from 1251 to 4336 MBq (33.8-117.2 mCi). The primary objectives were to assess tumor targeting, normal organ dosimetry, and safety. Antitumor effects were assessed by posttherapy changes in prostate-specific antigen and, when present, palliation of pain. Whole-body kinetics, blood and kidney clearance, skeletal dose, marrow dose, and urinary excretion of the isotope were assessed. Targeting of skeletal disease was observed over the period of quantification (4-168 h). Radiation doses to whole body, bladder, and kidney were well tolerated. The dose-limiting toxicity was myelosuppression (grade III) at 4107 MBq (111 mCi) and grade II at 296 MBq (80 mCi). Probe clearance (whole body) and urinary excretion measurements were highly correlated. Of the six patients treated at the highest dosage schedules (three at 1510 MBq/m2 and three at 1665 MBq/m2), three showed a posttherapy decline in prostate-specific antigen of 50% or more. The declines were not sustained. The determination of total activity retained at 24 h, as well as an estimate of marrow dose, correlated with the amount of myelosuppression observed. These results suggest that a single 24-h measurement of retained activity would allow individualized dosing and an improved therapeutic index relative to fixed dosing schema. Repetitive dosing is required to increase palliation.

Development of auditory function in the tammar wallaby Macropus eugenii

Auditory brainstem responses (ABRs) were evoked in developing wallabies by click and tone burst stimuli delivered by bone conduction and air conduction, at progressive stages of post-natal (pouch) life. ABRs were recorded through the onset of auditory responses (95-110 days), the opening of the external ear canal (125-130 days) and the maturation of ABR thresholds and latencies to values corresponding to those in adults ( > 180 days). ABRs were evoked in response to bone-conducted clicks some days prior to the age at which an acoustically evoked response was first observed (around 95 days of pouch life). ABRs could be evoked by bone-conducted and intense air-conducted stimuli prior to opening of the ear canal. A trend of decreasing threshold and latency with age was observed for both modes of stimulation. The morphology of the ABR became more complex, according to both increased age and increased stimulus intensity. The ABR waveforms indicated relatively greater mechanosensitivity to bone-conducted stimuli than to air-conducted stimuli, prior to opening of the ear canal. Following opening of the ear canal, thresholds to air-conducted clicks and tones were substantially reduced and decreased further over the next 10-20 days, while thresholds to bone-conducted clicks continued slowly to decrease. Thresholds to tone bursts in the centre frequency range (4-12 kHz) remained less than those for low (0.5-1.5 kHz) and higher (16 kHz) frequencies. Latencies of an identified peak in ABR waveforms characteristically decreased with age (at constant stimulus intensity) and with stimulus intensity (for a given age). ABR waveforms obtained at progressive ages, but judged to be at corresponding sensation levels, underwent maturational changes, independent of conductive aspects of the wallabies' hearing, for 2-3 weeks after opening of the ear canal.

Auditory brainstem response in tammar wallaby (Macropus eugenii)

Auditory brainstem responses (ABR) elicited by click and tonal stimuli were recorded from the tammar wallaby (Macropus eugenii), a marsupial mammal. The morphology, threshold, amplitude, and latency of ABRs recorded in the tammar wallaby are similar to those of other marsupials and mammals used in auditory research, including humans. Thresholds determined by an algorithm employing cross-correlation and by conventional visual detection methods were comparable. The findings from this study indicate that tammar wallaby is a suitable model for auditory research and that algorithms employing cross-correlation are useful for detection of the ABR waveform.

Neural responses to free-field auditory stimulation in the superior colliculus of the wallaby (Macropus eugenii)

Auditory responses to free-field broad band stimulation from different directions were recorded from clusters of neurones in the superior colliculus (SC) of the anaesthetized tammar wallaby. The auditory responses were found approximately 2 mm beneath the first recording of visually evoked responses in the superficial layers, the vast majority being solely auditory in nature; only one recording responded to both auditory and visual stimulation. Responses to suprathreshold intensities displayed sharp spatial tuning to sound in the contralateral hemifield. Those from the rostral pole of the SC disclosed a preference for auditory stimuli in the azimuthal anterior field, whereas those in the caudal SC preferentially responded to sounds in the posterior field. A continuum of directionally tuned responses was seen along the rostrocaudal axis of the SC so that the entire azimuthal contralateral auditory hemifield was represented in the SC. Furthermore, tight spatial alignment was evident between the best position of the visual responses in the superficial layers in azimuth and the peak angle of the auditory response in the deeper layers.

Water stress affects the productivity, growth components, competitiveness and water relations of phalaris and white clover growing in a mixed pasture

The effect of water stress during summer and recovery after rain on herbage accumulation, leaf growth components, stomatal conductance and leaf water relations of white clover (Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) was studied in an established mixed pasture under dryland (dry) or irrigated (wet) conditions. Soil water deficits under dry conditions reached 150 mm and soil water potentials in the top 20 cm declined to nearly -2 MPa after 50 days of dry weather. Water stress severely restricted growth of both species but then after rain fell, white clover growth rates exceeded those of phalaris. Under irrigation, white clover produced twice the herbage mass of phalaris but under dry conditions herbage production was similar from both species. Leaf appearance rates per tiller or stolon were slightly higher for white clover than phalaris but were reduced by 20% under water stress in both species. Leaf or petiole extension rates were more sensitive to water stress than leaf appearance rates and declined by 75% in phalaris and 90% in white clover. The ratio of leaf or petiole extension rates on dry/wet treatments was similar for both species in relation to leaf relative water contents, but in relation to leaf water potentials phalaris maintained higher leaf growth rates. Phalaris maintained a higher leaf relative water content in relation to leaf water potentials than did white clover and also maintained higher leaf water potentials in relation to the soil water potential in the top 20 cm. Stomata1 conductances for both species declined by 80-90% with increasing water stress, and both species showed similar stomatal responses to bulk leaf water potentials and leaf relative water contents. It is suggested that the poorer performance of white clover under water stress may be due principally to a shallower root system than phalaris and not due to any underlying major physiological differences. The white clover cultivar used in this study came from the mediterranean region and showed some different responses to water stress than previously published evidence on white clover. This suggests genetic variation in responses to water stress may exist within white clover. To maintain white clover in a pasture under dry conditions it is suggested that grazing practices aim to retain a high proportion of growing points.