Biomedical subjects

A Wang

Publications and source records attributed to A Wang.

At least 55 records · Page 3Linked to original sources

PubMed2001

Lingual ultrastructure of the long-finned pilot whale (Globicephala melas).

Microscopic studies on the cetacean tongue are limited and, to date, only a few ultrastructural reports on dolphins have been published. This report presents the initial description of the lingual ultrastructure of the long-finned pilot whale. The lingual integumental surface was smooth, lacking papillae, although flaking of outer stratum corneum cells could be observed at high resolution. The keratinocytes of the stratum spinosum of the epidermis resembled those of cetacean skin on other regions of the body. The similarities included the presence of cytoplasmic lipid droplets around the nuclei of stratutm spinosum cells, a lingual feature not seen in terrestrial mammals. Keratin intermediate filaments were numerous and occasionally formed aggregates of circular whorls. At cell surfaces, bundles of keratin intermediate filaments were frequently observed inserting into desmosomal plaques. Pigment granules were not evident and organelles were sparse. Stratum corneal cells contained nuclear remnants (parakeratosis) and small multivesicular bodies, and the corneal layer was approximately 18 cells thick. The nuclei of the stratum basale keratinocytes possessed exceptionally numerous and deep clefts. The dermis was nondistinctive. The skeletal muscle of the tongue was arranged in widely separated fasiculi containing small numbers of muscle fibres. Typical fine structure of skeletal muscle bands and tubular elements was observed by transmission electron microscopy.

Animals↗

PubMed2001

Fluorophore-assisted carbohydrate electrophoresis (FACE) of glycosaminoglycans.

OBJECTIVE: Quantitation and analyses of the fine structure of glycosaminoglycans are increasingly important for understanding many biological processes, including those most critical for understanding skeletal biology. We have developed a novel procedure, fluorophore-assisted carbohydrate electrophoresis (FACE), for determination of glycosaminoglycan fine structure and estimation of chain length. DESIGN: FACE utilizes enzymes that cleave glycosaminoglycans to create products, usually disaccharides, characteristic of the enzyme specificity. Each cleavage exposes a new reducing terminus that is fluorotagged by reductive amination with 2-aminoacridone. The tagged products are then displayed by electrophoresis, identified by their characteristic migration and chemistry, and quantitated by their molar fluorescence. RESULTS: Each class of glycosaminoglycan and the enzymes specific for each class are discussed. Specific application of the FACE technology is shown for analysis of the glycosaminoglycans on aggrecan isolated from knee cartilage of 5- and 68-year-old patients, and assessment of hyaluronan oligosaccharides. CONCLUSIONS: The FACE technology is a powerful tool for analysis of all four classes of glycosaminoglycans obtained from a wide variety of biologic sources. While the FACE protocols are relative simple, they provide a wealth of information including quantitation in the pmole range, determination of fine structure, and estimation of chain length.

Aged↗

PubMed2001

Cardiac conduction abnormalities in endocarditis defined by the Duke criteria.

BACKGROUND: Cardiac conduction abnormalities occur in endocarditis and have been associated with infection extension and increased mortality. There have been no prospective studies of electrocardiographic (ECG) conduction changes in endocarditis. We examined the incidence of ECG changes in a large prospective cohort with suspected endocarditis and correlated changes with echocardiographic evidence of invasive infection and mortality. METHODS: One hundred thirty-seven of 1396 (10%) suspected cases of endocarditis were classified as "definite" or "possible" by the Duke criteria and had an interpretable ECG. ECG conduction changes were classified as old (pre-existing hospitalization), new (evident on admission or developed during hospitalization), or indeterminate. New or indeterminate abnormalities were considered "ECG conduction changes." Echocardiogram results were reviewed to identify infected valves and invasive infection. RESULTS: ECG conduction changes were present in 36 of 137 (26%) patients. Patients with ECG conduction changes were more often male (69% vs 46%, P =.005) and had prosthetic valves (47% vs 23%, P <.001). There were no significant differences in microbiology results or treatment with cardiac surgery. In 76 (55%) patients, at least one infected valve was identified by echocardiography; 15 of 76 (20%) patients were determined to have evidence of invasive infection. Eight of 15 (53%) invasive infections exhibited ECG conduction changes compared with 16 of 61 (26%) isolated valve infections (P =.046). Eleven of 36 (31%) patients with ECG conduction changes died during hospitalization compared with 15 of 101 (15%) patients without changes (P =.039). CONCLUSIONS: ECG conduction changes commonly occur in endocarditis despite more sensitive diagnostic criteria and are associated with increased mortality and invasive infection.

Arrhythmias, Cardiac↗

PubMed2001

Correlation between quantitative left atrial spontaneous echocardiographic contrast and intact fibrinogen levels in mitral stenosis.

An association between left atrial spontaneous echocardiographic contrast (LASEC) and thromboembolic events has been recognized. However, the appearance of LASEC and the assessment of its intensity are gain dependent. To evaluate the relation between LASEC intensity and coagulation activity, 11 patients with mitral stenosis underwent transesophageal echocardiography with quantitative integrated backscatter assessment of LASEC. Right and left atrial blood samples were evaluated for concentrations of coagulation markers, including intact fibrinogen, fibrinopeptide A, D-dimer, prothrombin fragment 1+2, and thrombin-antithrombin III complex. The patients were found to have significantly higher mean left atrial concentrations compared with right atrial concentrations of thrombin-antithrombin III (28.46 +/- 21.05 versus 3.21 +/- 7.16 ng/mL, respectively; P =.001) and fibrinopeptide A (32.78 +/- 17.54 versus 7.42 +/- 8.27 nmol/L, respectively; P <.001). Intact fibrinogen levels were similar in both atria, and a strong, direct correlation existed between left and right atrial intact fibrinogen levels (r = 0.78, P =.005). Quantitative integrated backscatter of LASEC correlated directly with left atrial fibrinogen level (r = 0.78, P =.013) but not with markers of thrombin generation (thrombin-antithrombin III) or activity (fibrinopeptide A). Our results confirm that patients with mitral stenosis have evidence of a regional hypercoagulable state in the left atrium. However, the intensity of LASEC assessed by quantitative integrated backscatter correlates with both right and left atrial intact fibrinogen level, a systemic marker of coagulation.

Adult↗

PubMed2001

Modulation of endogenous nitric oxide synthase in experimental acute pancreatitis: role of anti-ICAM-1 and oxygen free radical scavengers.

OBJECTIVE: To evaluate, in an experimental model of acute pancreatitis, the impact of nitric oxide on the disease process and the interaction between nitric oxide and oxygen free radicals. SUMMARY BACKGROUND DATA: Nitric oxide and oxygen free radicals are involved in the pathophysiology of acute pancreatitis. It is well established that oxygen free radicals play an important role in the development of pancreatic cell damage and remote organ failure, but the impact of nitric oxide on the disease process and the interactions between the two radical species remain controversial. METHODS: Necrotizing pancreatitis (NP) was induced in Wistar rats by intraductal sodium taurocholate infusion after pretreatment with isotonic saline (NP-S), superoxide dismutase/catalase (NP-SOD/CAT), or an anti-ICAM-1 antibody (aICAM-1). Sham-operated rats received isotonic saline (SHX). After an observation period of 5 minutes and 24 hours, the pancreas was removed for microscopy, glutathione, and myeloperoxidase (MPO) analysis. The inducible NO synthase (NOS-2) was detected by Western blotting or RT-PCR. Serum was analyzed for nitrite/nitrate (NO2-/NO3-) and S-nitrosothioles (RSNO), while plasma was used to assay for trypsinogen activation peptides (TAP). RESULTS: NP-S animals showed a significant decrease in GSH levels after NP-induction as compared with animals under therapy. Increased MPO levels in the NP-S group were significantly reduced by aICAM-1 while SOD/CAT injection showed no changes. Serum NO-derivatives peaked at 12 hours while TAP levels had a maximum at 6 hours after NP induction, and were lower after aICAM-1 application SOD/CAT treatment increased both parameters. Extended acinar cell damage and inflammatory infiltrate developed in NP-S animals and was significantly improved by SOD/CAT and aICAM-1 treatment. RT-PCR and Western-blot analysis revealed NOS-2 expression in the NP-S group, which was reduced by radical scavengers and aICAM-1. CONCLUSION: Enhanced nitric oxide synthase expression and increased nitric oxide derivatives are found during severe acute pancreatitis. Oxygen free radicals and neutrophils seem to be potent and important regulation mechanisms for nitric oxide synthase activity and nitric oxide-mediated toxicity but imply only a secondary role for nitric oxide in the local pathologic mechanism of this disease.

Animals↗

PubMed2001

Specific inhibition of coxsackievirus B3 translation and replication by phosphorothioate antisense oligodeoxynucleotides.

The 5' and 3' untranslated regions (UTRs) of coxsackievirus B3 (CVB3) RNA form highly ordered secondary structures that have been confirmed to play important regulatory roles in viral cap-independent internal translation initiation and RNA replication. We previously demonstrated that deletions in different regions of the 5' UTR significantly reduced viral RNA translation and infectivity. Such observations suggested strongly that viral RNA translation and replication could be blocked if highly specific antisense oligodeoxynucleotides (AS-ODNs) were applied to target crucial sites within the 5' and 3' UTRs. In this study, seven phosphorothioate AS-ODNs were synthesized, and the antiviral activity was evaluated by Lipofectin transfection of HeLa cells with AS-ODNs followed by infection of CVB3. Analysis by Western blotting, reverse transcription-PCR, and viral plaque assay demonstrated that viral protein synthesis, genome replication, and infectivity of CVB3 were strongly inhibited by the AS-ODNs complementary to different regions of the 5' and 3' UTRs. The most effective sites are located at the proximate terminus of the 5' UTR (AS-1), the proximate terminus of the 3' UTR (AS-7), the core sequence of the internal ribosome entry site (AS-2), and the translation initiation codon region (AS-4). These AS-ODNs showed highly sequence-specific and dose-dependent inhibitory effects on both viral protein synthesis and RNA replication. It is noteworthy that the highest inhibitory activities were obtained with AS-1 and AS-7 targeting the termini of the 5' and 3' UTRs. The percent inhibition values of AS-1 and AS-7 for CVB3 protein VP1 synthesis and RNA replication were 70.6 and 79.6 for AS-1 and 73.7 and 79.7 for AS-7, respectively. These data suggest that CVB3 infectivity can be inhibited effectively by AS-ODNs.

Enterovirus B, Human↗

PubMed2001

Effect of contact stress on friction and wear of ultra-high molecular weight polyethylene in total hip replacement.

This paper studies the effect of contact stress on friction and wear of ultra-high molecular weight polyethylene (UHMWPE) acetabular cups by means of friction and wear joint simulator testing under serum lubrication. For a given applied load, increasing the contact stress by increasing the ball/socket radial clearance decreased both the coefficient of friction and the wear rate. Friction and wear were highly correlated. The dependence of friction on contact stress for the UHMWPE socket under serum lubrication was similar to that of semi-crystalline polymers under dry sliding. This finding indicates the occurrence of partial dry contact at asperity levels for the metal-polyethylene ball-in-socket joint under serum lubrication.

Arthroplasty, Replacement, Hip↗

PubMed2001

[Study on the mode of inheritance for familial polycystic ovary syndrome].

OBJECTIVE: To investigate the mode of inheritance of polycystic ovary syndrome(PCOS). METHODS: The first female relatives with irregular cycle and the first male relatives with premature balding in each nuclear family were designated the affected. Their prevalence rates in families were respectively calculated. Analyses of segregation ratio were carried out among 139 nuclear families with PCOS by the methods of simple segregation and complex segregation of genetic epidemiology, respectively. RESULTS: The prevalence rates of irregular cycle among mothers and sisters with PCOS were 37.4% and 33.1% respectively, and the prevalence rates of premature balding among fathers and brothers of patients were 19.4% and 6.5%, respectively. The simple segregation analysis indicated that the segregation ratio of PCOS trait in siblings was 0.3023, the complex segregation analysis indicated that it fitted in with the inheritance model of co-dominant disorder with full penetrance and sporadic cases. The frequency of homozygote of disease gene in population was 0.046. CONCLUSION: PCOS presents the mode of co-dominant inheritance with complete penetrance.

Female↗

PubMed2001

The suitability of hepatocyte culture models to study various aspects of drug metabolism.

Since the liver is the main organ involved in the metabolism and the toxicity of xenobiotics, isolated rat hepatocytes have been increasingly used in recent years as a model to identify pharmacological and toxicological responses of drugs. However, it is generally recognised that isolated hepatocytes retain most of their functions only for a short period. For this reason, numerous models and techniques have been developed to study and improve the metabolic capacity of hepatocytes in vitro over an extended time period and in application for drug metabolism studies. In the present study, we compared four different cell culture models to fulfill these requirements and have therefore harvested hepatocytes and cultured them in different culture systems over two weeks. In order to prove certain advantages or disadvantages of each model, we compared the metabolic capacity, albumin secretion, the release of cytosolic and mitochondrial enzymes, as well as the capacity to metabolise diclofenac (DF). We found that rat hepatocytes in all studied culture models (except the Unisyn Bioreactor) were able to metabolise DF to the same extent as found in vivo. However, the concentration of metabolites was found to decrease with culture time using the monolayer although the DF metabolite level in the collagen Sandwich culture was higher than that of the monolayer culture. The 3D-membrane bioreactor preserved the metabolic capacity for a prolonged period of time. The concentrations of DF metabolites in the Unisyn hollow fiber bioreactor were below the detection limit, which corresponded to other parameters such as albumin secretion and cytochrome P450 activity, disqualifying this culture system clearly for the use of in vitro primary hepatocyte cultures. The other three systems all have their place in drug metabolism with different advantages. However, our studies clearly showed that hepatocytes cultured within a collagen sandwich or in the 3D-membrane bioreactor qualify to study various aspects of drug metabolisms over a long time period. Further studies are needed to prove if the later two culture models may really help to reduce animal testing.

Alanine Transaminase↗

PubMed2001

[Retrospective analysis of 15 patients with fungal septicaemia].

OBJECTIVE: Study on the early diagnosis, antifungal therapy, and prophylaxis for fungemia. METHOD: Retrospective study of the clinical features, treatment and outcome of 15 patients with fungemia from August 1992 to September 2000 at Peking Union Medical College Hospital. RESULTS: The patients' ages ranged from 25 days (1 newborn) to 72 years (mean: 54.5 years in 14 patients); 11 were male. The length of hospitalization before fungemia varied from 7 days to 12 months (median: 1.5 months) in 14 patients who fulfilled criteria for nosocomial fungemia, another one with fungemia occurred outside of hospital. The main underlying conditions were: malignant disease (cancer, leukemia and acute aplastic anemia) in 10 patients (66.7%), infections following abdominal surgery in 2 patients (13.3%), trauma in 1 patient, rheumatic heart disease in 1 patient and 1 newborn. In this group the risk factors for fungemia included: prior antimicrobial therapy (14 of 15, 93.3%), steroids/cytotoxic chemotherapy (11 of 15, 73.3%), neutropenia (4/15, 26.7%), central venous catheterization and hyperalimentation (2 of 15, 13.3%). There were two or more risk factors in each of 11 patients. Fungal species isolated from 15 patients were: C. albicans (in 4), C. tropicalis (in 3), C. parapsilosis (in 3), C. sake (in 1), Trichosporon beigelii (in 1) and Yeast-like fungus (in 3). Before or during of fungemia, there were abnormal pulmonary signs or chest roentgenogram in 11 (73.3%), thrush in 2 (13.3%), enteritis in 2 (13.3%), urinary tract infection in 2 (13.3%) and endocarditis in 2 (13.3%). The overall mortality was 53.3% (8 of 15) and was 26.7%(4 of 15) duo to fungemia. Out of 7 survived patients, 4 were cured, 3 with fluconazole (length of therapy: 3-5 weeks) and 1 with a combination therapy of amphotericin B plus fluconazole (length of therapy: 3 months), other 3 were improved with fluconazole or amphotericin B (length of therapy: > 2 weeks). During the antifungal therapy, 2 patients with the complication of fungal endocarditis underwent surgical removal of vegetation on the infected valves. CONCLUSION: In this study, the most frequent infectious agents were Candida albicans and non-albicans Candida species. Early diagnosis is of importance to guide appropriate antifungal therapy and reduce mortality.

Adolescent↗

PubMed2001

[Diagnosis and treatment of primary trigeminal neurilemmoma].

OBJECTIVE: A series of 51 patients with trigeminal neurillemmoma were analyzed with respect to the clinical manifestations, radiologic features, operative approaches and factors influencing tumor total resection. METHODS: Three different approaches were used to remove the tumors according to the site of tumor growth. Tumors in middle fossa were removed via extended middle fossa approach or extended transpterion approach. Dumbbel tumors on petrosal bone were resected by presigmoid approach. Retrosigmoid approach was used to excise tumors in posterior fossa. RESULTS: Tumors removed completely in 80.0% of patients, 75.0% of the patients had a normal cranial nerve function after operation. Tumors recurred in two patients 2 years after operation. CONCLUSION: The new operative approach increases the complete tumor resection rate.

Adolescent↗

PubMed2001

Vascularized peripheral nerve trunk autografted in the spinal cord: a new experimental model in adult rats.

OBJECTIVE: To investigate the effect of vascularized peripheral nerve trunk autografted in spinal cord. METHODS: With modern microsurgical technique, vascularized peripheral median and ulnar nerve trunk autografted in the upper thoracic region of the spinal cord were established in 20 female adult rats. The origin and the termination of axons in the graft were studied by retrograde neuronal labeling with horseradish peroxidase (HRP). Cord, nerve grafts and some normal median an d ul nar nerves in the right upper limb were removed and sectioned for Bielschowsky's silver stain and haematoxylin and eosin (H&E) stain. Light and electron microscopic examination and electrophysiological examination were applied. RESULTS: The grafts were innervated by many new fibers. Studies with HRP indicated that new axons in graft were originated from intrinsic cent ral nervous system (CNS) neurons with their cell bodies from brain stem to s acral segments of spinal cord. Other axons arose from dorsal root ganglia at the level of graft and at least 19 distal segments to them. Together with electron microscopy, electrophysiological examination, silver and H&E stain, the results demonstrated that vascularized peripheral nerve trunk grafted in spinal cord attracted many neurons to grow into the nerve grafts. CONCLUSIONS: The findings implicate that CNS is able to regenerate much better in vascularized nerve autografted in spinal cord.

Animals↗

PubMed2001

[The Immunophenotypical features of t (8; 21) (q22; q22) acute myeloid leukemia].

OBJECTIVE: To study the predictive value of immunophenotypical features in t (8; 21) (q22; q22) acute myeloid leukemia (AML). METHODS: Morphological/cytochemical, flow cytometric immunophenotyping, cytogenetic analyses (MIC) and RT-PCR were performed in 294 previously untreated AML. RESULTS: (1) In 294 AML patients, t (8; 21) AML were 21.8% (64); in AML-M(2), t (8; 21) AML were 54.7%; and in t (8; 21) AML, AML-M(2) were 81.3%. (2) Compared with control group, CD(19) and CD(34) expressions were higher, and CD(33) expression was lower (P < 0.001) in t (8; 21) AML. (3) If the cut-off value of CD(19) positive was >or= 20%, CD(19) positive rate was 13.6% (40/294) in AML, and 50% (32/64) and 3.5% (8/230) (P < 0.001) in t (8; 21) AML and control group. (4) CD(19)(+) and/or CD(34)(+) t (8; 21) AML accounted for 90.6% (58/64) of t (8; 21) AML and CD(19)(-)/CD(34)(-) for 9.6% (6/64). CONCLUSION: In t (8; 21) AML, especially M(2)/t (8; 21), CD(19) and CD(34) expressions were high. CD(19) was one of predictive markers of t (8; 21) AML.

Adolescent↗

PubMed2001

[The adenovirus-mediated HSV-TK/GCV suicide gene system in the treatment of tongue carcinoma cell line].

OBJECTIVE: To study the effects of replication-defective recombinant adenovirus-mediated herpes simplex virus thymidine kinase (AdCMV HSV-TK)/ganciclovir (GCV) suicide gene system on tongue carcinoma cell line. METHODS: Replication-defective recombinant adenovirus containing CMV promoter were propagated in 293 cells, purified by cesium chloride gradient and titrated by tissue culture infectious doses50 (TCID50) methods. Infectivity test was used to determine the efficiency of adenoviral transduction into tongue carcinoma cell line (Tca8113 cell line) and RT-PCR was applied to detect the expression of TK gene after infecting Tca8113 cells. The killing effects and bystander effects of HSV-TK/GCV system on tongue carcinoma cells were detected with MTT assay. RESULTS: The adenoviral titration was about 2 x 10(10) plaque-forming units(PFU)/ml. The efficiency of adenoviral transduction into tongue carcinoma cells was more than 70 percent when multiplicity of infection (MOI) was more than 20. The recombinant adenovirus expressed TK gene after infecting Tca8113 cells in vitro. Adenovirus-mediated HSV-TK/GCV suicide gene system had killing effects on Tca8113 cells and these effects were related with time and GCV dose. The killing effects were poor after treated for 3 days and increased for 5 and 7 days. There had a good killing effect only when MOI was more than 20. When MOI was 80, GCV 5 x 10(-4) mol/L and treatment for 7 days, the viability of cells is only 4%. The bystander effect of this system on Tca8113 cells is poor. CONCLUSIONS: Only when most of the tongue carcinoma cells were transferred by AdCMV HSV-TK, HSV-TK/GCV suicide gene system has good killing effect on tongue carcinoma cell line.

Adenoviridae↗

PubMed2001

[Analyzing partial nucleotide and amino acid sequences of Chinese TTV isolates].

BACKGROUND: To investigate the prevalence of transfusion transmitted virus (TTV) and its sequence characterization in China. METHODS: TTV DNA was amplified by Semi-Nested-PCR, and the positive products were sequenced directly. RESULTS: The homology of partial nucleotide and amino acid sequences of 7 Chinese TTV isolates were 64.7%-98.4% and 62.7%-96.4% respectively when compared with Japanese isolate. Among 7 Chinese TTV isolates, the homology of partial nucleotide and amino acid sequences were 63.5%-98.4% and 60.2%-96.4% respectively. They differently belong to two genotypes and two subgenotypes. CONCLUSIONS: There exists TTV in China, and there might be several genotypes of Chinese TTV isolates.

Amino Acid Sequence↗

PubMed2000

Determination of thiols following their separation by CZE with amperometric detection at a carbon electrode.

The amperometric detection (AD) employing a carbon disk electrode as a working electrode to determine the thiol compounds, including cysteine (CYS), glutathione (GSH), 6-thiopurine (TP), and methimazole (MMI), following their separation by capillary zone electrophoresis (CZE) is described in this paper. The detection potential was chosen at +1100 mV and all analytes exhibit good response at this potential on the carbon disk electrode. The reproducibility, linearity, and recovery were evaluated under the optimum conditions. The four analytes can be baseline resolved within 20 min and the detection limits reached about 10(-6) mol/l of magnitude. The method was applied to the separation and determination of the actual thiol samples and the analytical results were satisfactory.

Carbon↗

PubMed2000

Molecular cloning and identification of full-length cDNA encoding high affinity Fc receptor for bovine IgG (Fc gamma RI).

The receptor I for the Fc region of immunoglobulin G (Fc gamma RI) is a member of the Ig superfamily with a high affinity, and it mediates antibody-dependent cellular cytotoxicity and immune complex clearance. In this study, a cDNA encoding the bovine Fc gamma RI was cloned. The full-length cDNA sequence is 1050 bp long with a short 5'- and long 3'-untranslated end regions, which codes for 349 amino acids and contains a signal peptide, an extracellular region with three Ig-like domains, and transmembrane and intracytoplasmic domains. Five potential N-linked glycosylation sites are recognized in this sequence. Compared with the sequences of human and mouse Fc gamma RI, the homologies of nucleotide sequences are 80 and 69% and homologies of deduced amino acid sequences are 66 and 55%, respectively. It is shown that the sequences of the monomeric IgG binding domain in these three species of Fc gamma RI are highly conserved.

Amino Acid Sequence↗

PubMed2000

Changes in hydrolytic enzyme activities of naïve Atlantic salmon Salmo salar skin mucus due to infection with the salmon louse Lepeophtheirus salmonis and cortisol implantation.

The changes in the activities of mucus hydrolytic enzymes and plasma cortisol levels were examined following infection of Atlantic salmon Salmo salar with the salmon louse Lepeophtheirus salmonis and these changes were compared with those resulting from elevated plasma cortisol. Salmon were infected at high (Trial 1; 178 +/- 67) and low (Trial 2; 20 +/- 13) numbers of lice per fish and the activities of proteases, alkaline phosphatase, esterase and lysozyme in the mucus, as well as plasma cortisol levels were determined. At both levels of infection, there were significant increases of protease activity over time (1-way K-WANOVA; Trial 1, p = 0.004; Trial 2, p < 0.001). On several sampling days, generally on later days in the infections, the mucus protease activities of infected fish were significantly higher than control fish (Student's t-tests; p < 0.05). In addition, zymography experiments demonstrated bands of proteases at 17 to 22 kDa in the mucus of infected salmon that were absent in the mucus from non-infected fish and absent in the plasma of salmon. The intensity of these protease bands increased in the mucus over the course of both infections. However, plasma cortisol levels were elevated only in the heavily infected fish from the first trial. At high infection levels (Trial 1), alkaline phosphatase activity was higher in the mucus of infected fish at all days (t-test, p < 0.05). However, at the lower infection level (Trial 2), the mucus alkaline phosphatase activity did not differ significantly between infected and non-infected fish. Esterase and lysozyme activities were very low and did not change with time nor between non-infected and infected salmon in either challenge. Mucus enzyme activities of cortisol-implanted salmon did not change over time, nor were there any differences in activities between cortisol-implanted and control salmon. The present study demonstrates biochemical changes resulting from sea lice infection of Atlantic salmon occurring at the site of host-pathogen interaction, the mucus layer. However, the origin of these enzymes, whether host or pathogen, remains to be determined.

Alkaline Phosphatase↗