A near-infrared-emission aza-BODIPY-based fluorescent probe for fast, selective, and "turn-on" detection of HClO/ClO. Talanta 2021;233:122581. [PMID: 34215073 DOI: 10.1016/j.talanta.2021.122581]

A novel near-infrared-emitting aza-BODIPY-based fluorescent probe with two tellurium atoms at two upper benzyl rings has been prepared and explored for its fluorescent sensing properties towards hypochlorous acid/hypochorite (HClO/ClO^-), which showed high selectivity and absolutely fluorescent "turn-on" phenomenon at 738 nm. The fluorescence of this probe was sufficiently quenched due to photoindued electron transfer by two tellurium atoms. Upon exposure to HClO/ClO^-, a strong near-infrared emission at 738 nm appeared with fluorescence quantum yields changing from 0 to 0.11. This remarkable fluorescence change was ascribed to the oxidation of both electron-rich tellurium atoms. The detection limit of this probe towards HClO/ClO^- was calculated to 0.09 μM in acetonitrile aqueous solution by the linear fluorescence change at 738 nm in the HClO/ClO^--concentration range of 0-30 μM. Interestingly, this probe was found to be applicable in a broad pH range (2-10). Meanwhile, the oxidized probe could be further responsive to biothiols with substantial fluorescence disappearance. The bioimaging experiments in RAW264.7 cells showed the appearance of intracellular near-infrared fluorescence after addition of HClO/ClO^- and PMA, and the fluorescence could also be reversed to be silenced by further introduction of GSH, confirming its potential application for exogenous and endogenous detection of HClO/ClO^- in living cells.

[Establishment of nutrition literacy core items for Chinese preschool children]

Objective: To establish the nutrition literacy core items for preschool children in China. Methods: The framework system and preliminary items of nutrition literacy were established through literature review and experts consultation. E-Delphi method was used to determine the nutrition literacy items. Nine experts in the field of nutrition, child and adolescent health, health education were invited to score the importance of each nutrition literacy item via Email. The judgment basis and familiarity of experts towards the items, active coefficient, authority coefficient and harmony coefficient were evaluated and analyzed to generate the final list of nutrition literacy items. Results: In the first round of E-Delphi consultation, the active coefficient and authority coefficient were 88.9%(8/9) and(0.88±0.07).The harmony coefficient was 0.350 (χ²=36.432, P=0.001). In the second round, the active coefficient and authority coefficient were 100% (9/9) and (0.89±0.11).The harmony coefficient was 0.347 (χ²=34.330, P<0.001). After qualitative and quantitative analyses, we identified the final list of nutrition literacy items consisting of two scales (basic knowledge, lifestyles and dietary behaviors), six subscales (food knowledge, food characteristic, food choice, dietary behavior, dietary safety, and physical activity)with 14 items in total. Conclusion: The framework system and core items of nutrition literacy are established for Chinese preschool children, which could provide a reference basis for the implementation of nutrition education project and the establishment of standardized evaluation tools.

A morphometric study of the thoracolumbar spine spinous process and lamina space in the Chinese

BACKGROUND

The aim of the study was to analyse the anatomical parameters of the thoracolumbar spine spinous process and lamina space for Chinese anatomic study, and provide an anatomical reference for its clinical operation.

MATERIALS AND METHODS

Samples from 24 adult autopsy subjects were obtained from the thoracolumbar spine spinous process and lamina space at levels T1 through L5. Direct measurements were made for the spinous process spacing distance, spinous process length, width, thickness and inclination angle, and the lamina space width and height.

RESULTS

1. Distance of the spine spinous process spacing: Thoracic part: The maximum tip distance was observed at T4~T5 level, and the minimum tip distance was observed at T9~T10 level. The maximum centre distance and root distance were observed at T11~T12 level, and the minimum were observed at T5~T6 level separately. Lumbar part: distance of spinous process spacing in lumbar part showed a decreasing pattern from L1~L2 to L5~S1. 2. Length, width, thickness of the spine spinous process: 1) The length of the spinous process: The upper border gradually increased from T1 to T6 and then decreased till T12 region. The centre region is T8 maximum, T11 minimum. The lower border length showed a decreasing trend from T1 to T12. Lumbar part: The length increased from L1 and reached maximum value at L3. Then, the length decreased gradually to reach minimum value at L5. 2) The width of the spinous process: The width showed an increasing trend from T1 to T12. Lumbar part: Maximum width was seen at L3 and a minimum L5. 3) The thickness of the spinous process: Tip thickness > Centre thickness > Root thickness in each thoracic and lumbar vertebra. Thoracic part: the maximum tip thickness is T1, T7 minimum, The maximum centre thickness is T12, T7 minimum. The maximum root height is T6, T9 minimum. Lumbar part: Maximum tip thickness was seen at L1, and a minimum L3. Maximum centre thickness was seen at L5, and a minimum L2. Maximum root thickness was seen at L2, and a minimum L1. 3. Inclination angle of the spine spinous process: The inclination angle gradually decreased from T1 to T7 to minimum value at T7 and then increased till T12 region. 4. Width and height of lamina space: 1) The width of lamina space: For thoracic part, the data became shorter gradually from T1~T2 to T5~T6, and then increased till to T11~T12. For lumbar part, the width of lamina space increased from T12~L1 to L5~S1. 2) The height of lamina space: In the thoracic vertebrae, the maximum height of centre region was observed at T11~T12 and the minimum mean value was observed at T3~T4. In the lumbar vertebrae, the height of the lamina space was gradually increased from T12~L1 to L5~S1.

CONCLUSIONS

This study reports morphometric data of the thoracolumbar spine spinous process and lamina space in the Chinese population, which provides an anatomic basis for thoracolumbar spine design of internal fixation, posterior surgery, puncture and epidural anaesthesia.

Determination of the Content of 4-FMA in Rat Plasma Samples by HPLC-MS/MS Method

Objective To develop a high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） method for the determination of the content of 4-fluoromethamphetamine （4-FMA） in rat plasma, and to provide a methodological basis for the study of the toxicokinetics of 4-FMA in rats. Methods Rat plasma samples were added into internal standard methamphetamine （MA）. Its proteins were precipitated with methanol and then separated with Poroshell 120 EC-C18 chromatographic column. A 0.1% formic acid aqueous solution and a 0.1% formic acid acetonitrile solution were used as the mobile phase at the flow rate of 0.4 mL/min. Electrospray ionization source was used for detection in the multiple reaction monitoring （MRM） mode. Results The linear relationship was good when the mass concentration of 4-FMA in plasma samples was in the range of 5-1 000 ng/mL （r>0.999）. The limit of detection （LOD） was 3 ng/mL and the limit of quantification （LOQ） was 5 ng/mL. The accuracy was expressed as relative error （RE）, and in the range of ±5%, the intra-day precision and inter-day precision （relative standard deviation, RSD） less than 9%, and the extraction recovery rate was more than 90%. The analysis and detection of plasma samples were completed within 2.5 min. Conclusion This study developed a HPLC-MS/MS method for the determination of 4-FMA in rat plasma samples. This method is accurate, rapid, simple and sensitive and can be applied to the study of toxicokinetics of 4-FMA.

[An analysis of relative factors, bacteriological profile and antibiogram of neonatal sepsis]

Objective: This study was designed to identify the relative factors, bacteriological profile and their antibiotic susceptibility pattern of neonatal sepsis. Methods: A retrospective survey was conducted on the clinical information, pathogen identification and antibiotic sensitivity results of 425 newborns with neonatal sepsis admitted to Nanjing Maternity and Child Health Care Hospital from 2010 to 2017. Of the 425 positive blood-cultures, 148 (34.82%) were early-onset neonatal sepsis (EOS) and 277 (65.18%) were late-onset neonatal sepsis (LOS). Clinical information and pathogen identification were compared between EOS and LOS. Antibiotic sensitivity of gram negative organisms (G(-)) and gram positive organisms (G(+)) were also detected. Results: The rates of premature delivery (78.70%, n=218), low birth weights (67.15%, n=186) and cesarean delivery (59.57%, n=165) were significantly increased in LOS (P<0.05) compared with those rates in EOS, which were 41.89% (n=62), 37.84% (n=56) and 46.62% (n=69). Parturients fever (18.24%, n=27) and meconium like amniotic fluid (25.68%, n=38) were significantly increased in EOS (P<0.05) compared with those rates in LOS, which were 7.94% (n=22) and 5.42% (n=15). Among the identified pathogen, the incidence of G(-) and G(+) bacteria were 216 (50.83%) and 201 (47.29%) respectively, and the rest was Candida glabrata (1.88%, n=8). Escherichia coli 68 (16.00%) was the predominant isolate followed by Klebsiella pneumoniae (13.18%, n=56). The detection rate of Hemolytic staphylococcus (10.81%, n=16) was significantly increased in EOS (P<0.001) compared with LOS (1.44%, n=4). However, the incidence of Klebsiella pneumonia (5.88%, n=44) was higher in LOS (P=0.024) compared with EOS (8.11%, n=12). Most of the gram positive isolates exhibited high resistance to penicillin (90.32%-100.00%) and cephalosporin group antibiotics (25.00%-100.00%). Similarly, the majority of the gram negative isolates showed higher resistance to ampicillin (83.33%-100.00%), but susceptible to aminoglycosides (0-11.76%), quinolones (0-17.65%) and β-lactams (0-5.88%). Conclusion: Among the study population, the percent of preterm, low birth weight and cesarean section were higher in LOS while parturients fever and meconium-like amniotic fluid were higher in EOS. The pathogens with the highest detection rate were Escherichia coli and Klebsiella pneumoniae. The results of antibiotic susceptibility test showed that common pathogens had high resistance to commonly used antibacterial drugs.

Aspirin-triggered Lipoxin A4 attenuates mechanical allodynia in association with inhibiting spinal JAK2/STAT3 signaling in neuropathic pain in rats

Aspirin-triggered Lipoxin A4 (ATL), as a Lipoxin A4 (LXA4) epimer, is endogenously produced by aspirin-acetylated cycloxygenase-2 (COX-2) and plays a vital role in endogenous anti-inflammation via the LXA4 receptor (ALX). Recent investigations have indicated that spinal neuroinflammation and the activation of the Janus Kinase 2 (JAK2)/Signal Transducers and Transcription Activators 3 (STAT3) signaling pathway are involved in neuropathic pain states. However, the effect of ATL on neuroinflammation and JAK2/STAT3 signaling in chronic constriction injury (CCI)-induced neuropathic pain in rats has not been well-studied. The present study demonstrated the anti-inflammatory and analgesic effect of ATL on neuropathic pain and assessed the role of spinal JAK2/STAT3 signaling on the effect of ATL. Intrathecal administration of ATL significantly attenuated mechanical allodynia via spinal ALX and inhibited the upregulation of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) on day 7 of CCI surgery. In addition, ATL markedly suppressed the upregulation of p-STAT3 induced by the neuropathic pain. Blockade of JAK2-STAT3 signaling with intrathecal administration of the JAK2 inhibitor AG490 or the STAT3 inhibitor S3I-201 clearly reduced mechanical allodynia and the upregulation of pro-inflammatory cytokines in CCI rats. Interestingly, inhibition of JAK2/STAT3 signaling via ATL or the specific signaling inhibitor (AG49, S3I-201) further promoted the increased expression of suppressor of cytokine signaling 3 (SOCS3) mRNA in the spinal cord induced by CCI surgery. Taken together, our results suggested that the analgesic effect of ATL was mediated by inhibiting spinal JAK2/STAT3 signaling and hence the spinal neuroinflammation in CCI rats.

Treating sewage using coimmobilized system of Chlorella pyrenoidosa and activated sludge

Chlorella pyrenoidosa was coimmobilized with activated sludge to produce algae-bacteria beads for sewage treatment. Hydrolysis/acidogenesis pretreatment could improve the symbiotic microenvironment of coimmobilized Chlorella pyrenoidosa and activated sludge, and as a result, promote the removal of nutrients (COD(cr), inorganic nitrogen and inorganic phosphorus) in the sewage. A photo-bioreactor combining hydrolysis/acidogenesis pretreatment and coimmobilized technique was designed to treat sewage continuously. The results show that, the removal efficiencies of COD(cr), NH4(+)-N and TP reached steady state after 4-days of experiment. The removal efficiencies of COD(cr), NH4(+)-N and TP were 59.6%, 59.0% and 60.3% respectively.

Generalized granuloma annulare associated with chronic hepatitis B virus infection

We describe a 63-year-old Chinese woman with generalized granuloma annulare (GGA) associated with chronic hepatitis B virus (HBV) infection for 10 years. She developed non-annular papule lesions after a previous infection of hepatitis B virus. Since then, her clinical course was aggressive with involvement of the trunk, extremities and neck. Histologically, granulomatous inflammations were found in the upper to mid dermis. The HBV DNA in these lesions was demonstrated by polymerase chain reaction (PCR). GGA was totally regressed after treatment of interferon-alpha for 3 months. To the best of our knowledge, GGA associated with chronic HBV infection has never been reported in literature. The prognostic significance of the association of granulomatous inflammation and virus infection is reviewed.

Cloning of the first invertebrate MAGE paralogue: an epitope that activates T-cells in humans is highly conserved in evolution

The MAGE (Melanoma Associated Antigen) family tumor-specific antigens are shared by a number of histologically different tumors. Till date, only human and mouse MAGE genes have been characterized. Our study describes the first non-mammalian member of MAGE super-family, DMAGE from D. melanogaster. A conceptual translation of the cDNA of DMAGE identifies a putative protein that contains a motif that shares eight out of nine amino acids with the previously identified promiscuous, HLA-A2 restricted antigenic epitope in the C-terminus of human MAGE-B1 and -B2. Similarly, this motif of DMAGE shares seven out of nine amino acids with the same antigenic epitope of human MAGE-A3 and -A12. Thus, the phylogeny of proteins that activate tumor specific T-cells in mammals as unmutated self-proteins began at least 100 million years earlier in evolution than the emergence of the adaptive immune system of higher vertebrates. Northern analysis revealed that DMAGE is a developmentally regulated gene highly expressed in adult fruit fly and in the embryo of D. melanogaster. In contrast, the expression level of the mRNA of DMAGE in fruit fly larva is substantially lower than in embryo and adult fly. We propose that studies of DMAGE on D. melanogaster may help define the function(s) of MAGE super-family genes.

Human herpesvirus 8 open reading frame 26 and open reading frame 65 sequences from multiple myeloma patients: a shared pattern not found in Kaposi's sarcoma or primary effusion lymphoma

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus, has been implicated in the pathogenesis of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman's disease, and recently multiple myeloma (MM). DNA sequence analyses of HHV-8 suggest that multiple HHV-8 strains exist. We extracted DNA from 24 patients with MM and 3 patients with monoclonal gammopathy of undetermined significance and compared HHV-8 open reading frames (ORFs) 26 and 65 sequences with those derived from patients with KS, PEL, and two HHV-8-positive PEL cell lines KS-1 and BC-1. ORF26 sequence data suggest that MM patients are consistently carriers of HHV-8 strain subtype C3. All MM patients also consistently revealed either a single bp deletion or substitution at position 112197 in ORF65. This unique alteration is not present in patients with KS or PEL or in PEL cell lines. It occurs in the portion of ORF65 that is known to be responsible for a serological response to HHV-8.

[Transformation of sainfoin by Agrobacterium rhizogenes LBA9402 Bin19 and regeneration of transgenic plants]

Hypocotyl segments of Onobrychis viciaefolia were transformed by Agrobacterium rhizogenes LBA9402 which harboured pBin19 and pRi1855. Seedling age and preculture time of hypocotyl segments influenced the transformation frequency. Paper electrophoresis revealed that 70% of single hairy root cultures could synthesize agropine. Calli were induced from hairy root segments on MS medium containing 0-9.05 mumol/L 2,4-D and 0-2.22 mumol/L 6-BA at first, then they were transferred onto MS0 medium without kanamycin for regeneration. Constitution and concentration of phytohormones in callus induction media affected subsequent regeneration of calluses on MS0 medium remarkably. Regeneration frequency and shoot number per callus declined when 2,4-D concentration in callus induction media increased from 4.52 to 9.05 mumol/L, while they ascended when 6-BA in callus induction media increased from 0 to 2.22 mumol/L. On MS medium supplemented with 4.52 mumol/L 2,4-D and 2.22 mumol/L 6-BA, only 14.2% hairy root segments could produce calluses, but the regeneration frequency reached 58.1% and the shoot number per callus was 37.2. In 32 analysed plants regenerated from 8 kanamycin resistant hairy root lines, 25 were nptII positive and showed different copy numbers.

[Decrease of cAMP and increase of amino acids contents in mouse brain after dihydroetorphine tolerance]

AIM

To study the mechanism of dihydroetorphine (DHE) tolerance.

METHODS

DHE tolerance was produced by repeated s.c. injections in progressively increased doses to mice for 8 d. The concentrations of amino acids and cAMP were detected by RP-HPLC/fluorescence assay and radioimmunoassay, respectively.

RESULTS

The basal contents of glutamic acid (Glu), aspartic acid (Asp), and GABA in whole brain (cerebellum removed) were increased respectively from 14.1 +/- 2.1, 3.0 +/- 0.4, and 1.8 +/- 0.8 mumol/g tissue in control mice to 17.2 +/- 2.2, 4.1 +/- 0.6, and 3.2 +/- 1.0 mumol/g tissue in tolerant mice, and the rates of increase were 22.0% (P < 0.05), 36.7% (P < 0.01), and 77.8% (P < 0.05 vs control), respectively. There was no significant difference in the basal contents of Gln (5.1 +/- 1.0 vs 4.5 +/- 1.7 mumol/g tissue of control). The basal contents of cAMP in hypothalamus and striatum were decreased respectively from 271 +/- 38 and 189 +/- 31 nmol/g tissue in control mice to 96 +/- 15 and 65 +/- 21 nmol/g tissue in tolerant mice (P < 0.01), and the rates of decrease were 64.6% and 65.6%, respectively. There was no significant difference of cAMP in cerebral cortex (72 +/- 20 vs 55 +/- 15 nmol/g tissue of control).

CONCLUSION

The increases of Glu, Asp, and GABA in brain and the decrease of cAMP in hypothalamus and striatum were involved in DHE tolerance.

Localization of Kaposi's sarcoma-associated herpesvirus in bone marrow biopsy samples from patients with multiple myeloma

We have recently demonstrated the presence of Kaposi's sarcoma-associated herpesvirus (KSHV) in cultured bone marrow (BM) stromal dendritic cells from all patients with myeloma studied. To show that these findings were not an artifact of tissue culture, we performed in situ hybridization (ISH) and polymerase chain reaction (PCR) to detect KSHV in BM core biopsies. Using ISH to open reading frame-72 (ORF 72), we localized KSHV to BM dendritic cells in 17 of 20 patients with myeloma, 2 patients with plasmacytosis associated with the acquired immunodeficiency syndrome, and 1 case of aplastic anemia. In contrast, BM from normal subjects (n = 4) and patients with lymphoma and leukemia (n = 21) did not contain KSHV. PCR amplification with KSHV primers demonstrated product in fresh BM biopsy samples from 6 of 7 myeloma patients, whereas three normal marrows contained no amplified product. These findings suggest that KSHV, possibly through alterations in the BM microenvironment and production of viral interleukin-6 (vIL-6), may stimulate and maintain abnormal plasma cell proliferation in myeloma and related disorders.

Kaposi's sarcoma-associated herpesvirus infection of bone marrow dendritic cells from multiple myeloma patients

Kaposi's sarcoma-associated herpesvirus (KSHV) was found in the bone marrow dendritic cells of multiple myeloma patients but not in malignant plasma cells or bone marrow dendritic cells from normal individuals or patients with other malignancies. In addition the virus was detected in the bone marrow dendritic cells from two out of eight patients with monoclonal gammopathy of undetermined significance (MGUS), a precursor to myeloma. Viral interleukin-6, the human homolog of which is a growth factor for myeloma, was found to be transcribed in the myeloma bone marrow dendritic cells. KSHV may be required for transformation from MGUS to myeloma and perpetuate the growth of malignant plasma cells.

Child malnutrition in China--present status and changing trend

Halving the malnutrition of under five of years has been set as one of the goals to be achieved by the year of 2000 by Chinese government. So it is important to know the present status of child malnutrition and its trend of changing, in order to predict the possible outcome of the achievement of the goal. According to the Child Survey carried out by the State Statistic Bureau (SSB) in 26 provinces and autonomous regions and 3 municipalities in 1992, the prevalence of malnutrition of under five was: moderate and severe underweight, stunting and wasting were 17.9%, 34.7% and 4.7% respectively. But there are significant differences among urban and rural children and between different provinces. The highest prevalence rate usually occurred in the second year of life of the children, and this may be the result of inadequate weaning food provided to the children. As compared with the data collected in 1987 by SSB in 9 provinces and autonomous regions, an impressive improvement in underweight has occurred within these 5 years. The average declined prevalence was 20.5%. It is specially true for urban children. To stunting, there was also improvement for urban children but not in the rural, resulting and over all increasing of prevalence by 5.9%. To wasting, the prevalence for urban children was low and remained at the same level while there was some what increase in the rural. So, according to these results, with constant economic development and more attempt made in areas and groups at risk, the goal to decrease malnutrition in half in terms of underweight could be reached by the year of 2000.

Immunocytochemical localization of ribonuclease in yolk granules of adult Rana catesbeiana oocytes

To determine the localization of the pyrimidine-guanine sequence-specific ribonuclease in Rana catesbeiana (bullfrog) oocytes, the RNase was first isolated and used to prepare a specific rabbit antiserum. Only one protein of similar molecular size to the RNase was immunoprecipitated from ovary homogenate by the antiserum, but two bands were observed by Western blotting analysis. These two proteins were shown by further purification of antibody and Western blotting analysis to have similar antigenicity. Immunoprecipitation and Western blotting of tissue homogenates showed that the RNase was found predominantly in the ovary, but not in other tissues. The specific localization of the RNase was determined by immuno-electron microscopy of oocyte sections incubated with the specific antiserum; the yolk granules, but not other organelles, were found to contain the RNase. Most of the RNase was evenly distributed in the lateral amorphous area of the yolk granule but not in the central yolk crystal area which contains stored vitellogenin proteins. Our results indicate that the RNase is compartmentalized in the yolk granules of oocytes, which might prevent damage to cellular RNAs.

Combined traditional Chinese medicine and Western medicine. Relieving effects of Chinese herbs, ear-acupuncture and epidural morphine on postoperative pain in liver cancer

In the evaluation of Chinese herbs (A), ear-acupuncture (B) and epidural morphine (C) to relieve postoperative pain and abdominal distension, sixteen male patients with primary liver cancer were observed. This study was conducted by means of orthogonal experiment and double blind, randomized design. The patients received various treatments according to the display of the orthogonal table L16(2)15 which corresponds to 2(3) factorial experiment design. C+ (morphine 2 mg) was given before the peritoneum was sutured. A+ (orally administered) and B+ were given 24 hours after operation. 50-100 mg of pethidine was given when the pain intensity VAS (0-100) exceeded 50-70. The observation parameters included plasma leucine enkephalin (LEK), postoperative total dosage of narcotics administered for 5 days, VAS for pain and pain reliever, abdominal distension, urinary retention, constipation, etc. The results were as follows: a. Patients who had received A (A+B+C+, A+B+C-, A+B-C-, A+B-C+); C (C+A+B+, C+A+B-, C+A-B+, C+A-B-), or B (B+A+C+, B+A+C-, B+A-C+, B+A-C-) produced better analgesic effects than those who had received placebo. The A, B, and C reduced narcotics 650, 450 and 550 mg respectively when compared with placebo. The effects of A and C were of statistical significance (P < 0.05), while AB, BC, and AC interactions were not found; b. A and B minimized abdominal distension and urinary retention, while C prolonged them. As compared with the placebo, A and B accelerated restoration of bowel peristalsis (P < 0.05, ANOVA). Both A and B decreased it for 165 hours, while epidural morphine prolonged it for 49 hours; and c.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoelectron microscopy of tissues processed by rapid freezing and freeze-substitution fixation without chemical fixatives: application to catalase in rat liver hepatocytes

We report on the immunohistochemical demonstration of an enzyme at the electron microscopic level using specimens processed by rapid freezing and the freeze-substitution technique without the use of any chemical fixatives. Fresh rat liver tissue blocks were rapidly frozen by the metal contact method using liquid nitrogen, and were freeze-substituted with acetone without any chemical fixatives at -80 degrees C. Some of the freeze-substituted tissues were embedded in Lowicryl K4M at -20 degrees C; the others were returned to room temperature and embedded in Epok 812 at 60 degrees C. Ultra-thin sections were stained using anti-peroxisomal catalase antibody by the protein A-gold technique. The ultrastructure of the hepatocytes was very well preserved compared with that of conventionally processed tissues. The labeling for catalase was confined to peroxisomes. When the labeling density was compared among freeze-substituted tissues and conventionally processed tissues, that of freeze-substituted and Lowicryl K4M-embedded tissues was the most intense. These results show the usefulness of freeze-substituted tissues for immunohistochemical analysis of cell organelles.