Differential regulation of microtubule-associated protein 1B (MAP1B) in rat CNS and PNS during development

MAP1B is a major cytoskeletal protein in growing axons and is strongly regulated during brain development. The present studies compare the expression of MAP1B mRNA, the protein, and its phosphorylated isoform in spinal cord and dorsal root ganglia (DRGs) with brain. In spinal cord and brain, MAP1B mRNA levels were highest in early stages of development, decreased several fold during postnatal development, and remained low in adults. In contrast, there were no significant changes of MAP1B mRNA levels during development of DRG and they remained high in adults. The levels of MAP1B protein decreased in brain and spinal cord in parallel with the changes of their mRNA. The protein levels in DRG remained relatively high but declined in the sciatic nerve. Phosphorylated MAP1B was expressed in high levels during the early stages of development in brain, spinal cord, and sciatic nerve and decreased rapidly to undetectable levels postnatally except for sciatic nerve where it remained detectable. Immunohistochemical analysis showed that phosphorylated MAP1B was absent from DRG cell bodies at all stages but was present in axons of DRG and motor neurons in both spinal cord and sciatic nerve. Immunostaining also confirmed Western blot analysis indicating that MAP1B was initially abundant within the spinal cord but was at later stages present only in motor neurons and the central processes of DRG neurons. These results reflect differential distribution of MAP1B isoforms at different stages of development and in different regions of the nervous system.

[Histopathological study on traumatic facial nerve injury in the rabbits]

Six patterns of injuries (exposure, compression, crush, stretch, division and post-division anastomosis) were analysed in 136 facial nerve buccal branches of 68 rabbits in order to establish the experimental model for study of traumatic facial nerve injury. Changes of histopathology at definite time were studied. The results showed that: exposure can create degree I injury; compression, stretch and crush can create degree II-III injury; the prognosis in anastomosis group was obviously better than unanastomosis group. In moderate to serious injuries, changes of histopathology and ENoG were synchronized, but were not so in mild and later stage of serious injury. The 15th day postinjury was the best time of estimating the facial nerve function clinically. The area of injury would obviously influence the mylin lesion, while the quality and degree of injury would obviously influence the axonal lesion.

Noradrenergic suppression of synaptic transmission may influence cortical signal-to-noise ratio

Norepinephrine has been proposed to influence signal-to-noise ratio within cortical structures, but the exact cellular mechanisms underlying this influence have not been described in detail. Here we present data on a cellular effect of norepinephrine that could contribute to the influence on signal-to-noise ratio. In brain slice preparations of the rat piriform (olfactory) cortex, perfusion of norepinephrine causes a dose-dependent suppression of excitatory synaptic potentials in the layer containing synapses among pyramidal cells in the cortex (layer Ib), while having a weaker effect on synaptic potentials in the afferent fiber layer (layer Ia). Effects of norepinephrine were similar in dose-response characteristics and laminar selectivity to the effects of the cholinergic agonist carbachol, and combined perfusion of both agonists caused effects similar to an equivalent concentration of a single agonist. In a computational model of the piriform cortex, we have analyzed the effect of noradrenergic suppression of synaptic transmission on signal-to-noise ratio. The selective suppression of excitatory intrinsic connectivity decreases the background activity of modeled neurons relative to the activity of neurons receiving direct afferent input. This can be interpreted as an increase in signal-to-noise ratio, but the term noise does not accurately characterize activity dependent on the intrinsic spread of excitation, which would more accurately be described as interpretation or retrieval. Increases in levels of norepinephrine mediated by locus coeruleus activity appear to enhance the influence of extrinsic input on cortical representations, allowing a pulse of norepinephrine in an arousing context to mediate formation of memories with a strong influence of environmental variables.

[Interleukin-8, a regulator of inflammation in gingival crevicular fluid]

The role of interleuking-8 (IL-8), a neutrophil-attracting and-activating cytokine, was investigated in gingival crevicular fluid (GCF). ELISA was used to detect the levels of IL-8 in GCF collected from 54 adult periodontitis (AP) patients (105 teeth) and 24 healthy subjects (54 teeth). The results showed that 1. The role of IL-8 was dependent upon the concentration of IL-8 in GCF. IL-8, in the low concentration (< or = 30 micrograms/L), was positively correlated with bleeding index (r = 0.36, P < 0.01). While in the high concentration (> 30 micrograms/L), was negatively correlated with bleeding index and probing depth (r = -0.54 and r = -0.65 respectively, P < 0.01). In the majority of periodontitis sites (91%), the concentration of IL-8 in GCF were lower than 30 microliters/L. IL-8 most likely acted as pro-inflammatory factor in these teeth. 2. IL-8 was a two-way regulator of inflammation, pro-inflammation and anti-inflammation. The threshold of IL-8 between inducing and suppressing inflammation was approximately 30 micrograms/L. Within the confined range, IL-8 concentration greater than 30 micrograms/L could be inflammation suppressive, while a less-than-30 micrograms/L concentration of IL-8 might become inflammation inducing.

Modeling, chemistry, and biology of the benzolactam analogues of indolactam V (ILV). 2. Identification of the binding site of the benzolactams in the CRD2 activator-binding domain of PKCdelta and discovery of an ILV analogue of improved isozyme selectivity

Protein kinase C (PKC) is a complex enzyme system comprised of at least 11 isozymes that serves to mediate numerous extracellular signals which generate lipid second messengers. The discovery of isozyme-selective activators and inhibitors (modulators) of PKC is crucial to ascertaining the role of the individual isozymes in physiological and pathophysiological processes and to manipulating their function. The discovery of such small molecule modulators of PKC is at present a largely unmet pharmacological need. Herein we detail our modeling studies which reveal how the natural product indolactam V (ILV) and its 8-membered ring analogue, the benzolactam 15, bind to the CRD2 activator domain of PKC. These modeling studies reveal that not all PKC ligands possess a common pharmacophore, and further suggest an important role of specific hydrophobic contacts in the PKC-ligand interaction. The modeling studies find strong experimental support from mutagenesis studies on PKC alpha that reveal the crucial role played by the residues proline 11, leucine 20, leucine 24, and glycine 27. Next, we describe the synthesis of two 8-substituted benzolactams starting from L-phenylalanine and characterize their isozyme selectivity; one of the two benzolactams exhibits improved isozyme selectivity relative to the n-octyl-ILV. Lastly, we report inhibition of cellular proliferation of two different breast carcinoma cell lines by the benzolactam 5 and show that the compound preferentially down-regulates PKCbeta in both cell lines.

Oxidation of 4-methoxymandelic acid by lignin peroxidase. Mediation by veratryl alcohol

The mechanism of veratryl alcohol-mediated oxidation of 4-methoxymandelic acid by lignin peroxidase was studied by kinetic methods. For monomethoxylated substrates not directly oxidized by lignin peroxidase, veratryl alcohol has been proposed to act as a redox mediator. Our previous study showed that stimulation of anisyl alcohol oxidation by veratryl alcohol was not due to mediation but rather due to the requirement of veratryl alcohol to complete the catalytic cycle. Anisyl alcohol can react with compound I but not with compound II. In contrast, veratryl alcohol readily reduces compound II. We demonstrate in the present report that the oxidation of 4-methoxy mandelic acid is mediated by veratryl alcohol. Increasing veratryl alcohol concentration in the presence of 2 mM 4-methoxymandelic acid resulted in increased oxidation of 4-methoxymandelic acid yielding anisaldehyde. This is in contrast to results obtained with anisyl alcohol where increased concentrations of veratryl alcohol caused a decrease in product formation. ESR spectroscopy demonstrated that 4-methoxymandelic acid caused a decrease in the enzyme-bound veratryl alcohol cation radical signal, which is consistent with its reaction at the active site of the enzyme.

Mobilization of predominantly Philadelphia chromosome-negative blood progenitors using cyclophosphamide and rHUG-CSF in early chronic-phase chronic myeloid leukaemia: correlation with Sokal prognostic index and haematological control

Mobilization of Philadelphia chromosome (Ph) negative blood progenitors was attempted in 23 newly diagnosed chronic myeloid leukaemia (CML) patients using a regimen of cyclophosphamide (CY) 5 g/m2 and rHUG-CSF 150 microg/m2 daily. This regimen was well tolerated with no major adverse events reported. More than 2 x 10(6)/kg CD34+ cells were collected in 21 patients (91%). Predominantly Ph-negative mobilization (0-25% Ph-positive) was seen in 30% of cases overall and was confined to patients with a Sokal prognostic score < 1 (7/11 with Sokal score <1; 0/12 with Sokal score > or = 1). Within the low Sokal index group, a low WBC count pre-mobilization and a low WBC nadir both correlated strongly with Ph-negative mobilization (P = 0.006 and 0.02 respectively). Five of 19 patients receiving at least 6 months of Roferon A therapy post mobilization achieved a major cytogenetic response; all five patients were Ph-negative mobilizers. Therefore CML patients can be divided into a good-prognosis group in whom predominantly Ph-negative progenitors can be mobilized using a regimen of moderate intensity if haematological control is achieved pre-mobilization, and a poor-prognosis group for whom predominantly Ph-positive cells are mobilized with this regimen regardless of haematological control.

[The behaviour and treatment of myoepithelial carcinoma of salivary glands]

Nineteen cases of myoepithelial carcinoma (malignant myoepithelioma) in salivary glands were studied clinicopathologically. The clinical features are as follows: arise most frequently within the parotid glands, followed by the submandibular glands; rapidly enlarging mass with extensive invasion of the surrounding tissues in some cases; low rate of cervical lymph node metastasis but high rate of distant metastasis; very frequent recurrence after surgical excision; and poor prognosis. The carcinoma belongs to the high grade malignant tumor. It must be treated radically. The elective neck dissection is generally unnecessary. It is resistant to radiotherapy. It is possible to get rather good result in limited recurrent tumors by prompt surgery.

Golgi GDP-mannose uptake requires Leishmania LPG2. A member of a eukaryotic family of putative nucleotide-sugar transporters

The synthesis of glycoconjugates within the secretory pathway of eukaryotes requires the provision of lumenal nucleotide-sugar substrates. This is particularly important for eukaryotic microbes such as Leishmania because they must synthesize considerable amounts of extracellular and cell surface glycoconjugates that play significant roles in the infectious cycle. Here we used properly oriented sealed microsomes to characterize lumenal uptake of GDP-Man in Leishmania donovani. In this system, GDP-Man uptake was saturable with an apparent Km for GDP-Man of 0.3 microM and facilitated its use as a donor substrate for lipophosphoglycan (LPG) synthesis. A lpg2(-) deletion mutant showed loss of GDP-Man but not UDP-Gal uptake, which was restored by introduction of the gene LPG2. Immunoelectron microscopy localized an active, epitope-tagged LPG2 protein to the Golgi apparatus. Thus, LPG2 is required for nucleotide-sugar transport activity and probably encodes this Golgi transporter. LPG2 belongs to a large family of eukaryotic genes that potentially encode transporters with different substrate specificities and/or cellular locations. In the future, the amenability of the Leishmania system to biochemical and genetic manipulation will assist in functional characterization of nucleotide-sugar transports from this and other eukaryotes. Furthermore, since LPG2 plays an important role in the Leishmania infectious cycle and mammalian cells lack a Golgi GDP-Man transporter, this activity may offer a new target for chemotherapy.

Expression of the spinach betaine aldehyde dehydrogenase (BADH) gene in transgenic tobacco plants

Plasmid pLS9 contains a 1.5-kb of spinach cDNA including its complete open reading frame. The 1.5-kb BADH cDNA was cut from pLS9 using restriction enzyme and was inserted into the expression cassette of plasmid pYH between the CaMV 35S promoter and polyA signal sequence. The 35S-BADH cDNA-polyA fragment of pYH was cloned into a polylinker cloning site of the binary vector pBin19. The resulting plasmid pBinBADH-S was transferred to Agrobacterium tumefacies LBA4404. The tobacco plants were transformed with strain LBA4404 containing pBinBADH-S, and more than ninety kanamycin-resistant transformants were selected. Polymerase chain reaction (PCR) detection showed that more than 60% of the transformed tobacco plants contained the foreign BADH gene. The Western blot analysis, BADH enzymatic assay, specific stain for BADH activity, and the test for salt tolerance showed that BADH gene was normally expressed in the transgenic tobacco plants. The BADH enzymes also presented in chloroplasts and cytosol of the transgenic plants. The transgenic tobacco plants having strong expression of BADH gene had strong ability to tolerate high salt stress.

[Determination of emodin in kangnaoshuai capsules and in radix Polygoni multifori by thin layer chromatography scanning]

The content of emodin in Kangnaoshuai Capsules was determined by TLC scanning. The method is simple and the result is accurate. The average recovery is 99.17% and RSD is 1.14%. The content of emodin in Radix Polygoni Multiflori was also determined by the same method. The method is useful in quality control of products.

Estrous cycle phase variations in visceromotor and cardiovascular responses to colonic distension in the anesthetized rat

Visceromotor and cardiovascular responses to colonic distension were measured in female rats, anesthetized with halothane in oxygen, in the proestrus, estrus, metestrus and diestrus phases of the estrous cycle. Ten rats were studied in each group and responses were measured at 5-min intervals for 60 min. A mixed model analysis of variance showed that there was no real change in either the visceral or cardiovascular response with time. There was a highly significant difference in visceromotor responses between the phases of the estrous cycle (P < 0.001). During the phase of proestrus the balloon pressure at which a response was triggered was much lower, with a mean value (95% confidence interval) of 18.7 (16.1, 21.8) mmHg, than the other phases with mean values (95% confidence interval) of 31.9 (27.4, 37.2) mmHg for estrus, 28.1 (24.2, 32.8) mmHg for metestrus, and 31.1 (26.7, 36.3) mmHg for diestrus. The mean arterial blood pressure increased in all groups (range 3.2, 5.4%) as a response to the stimulus, but there was no associated heart rate variability and no significant differences in cardiovascular changes between the groups (P = 0.6). The visceromotor responses measured during the phase of proestrus occurred at a significantly lower threshold than in the other phases of estrous.

Detection of Borrelia burgdorferi DNA in granulomatous tissues from patients with sarcoidosis using polymerase chain reaction in situ technique

To investigate the correlation between sarcoidosis and Borrelia burgdorferi (Bb) infection, flagella DNA of Bb were detected in 23 granulomatous tissue specimens from patients with confirmed sarcoidosis using polymerase chain reaction in situ technique (in situ PCR) and the antibodies to Bb were examined in 55 serum samples obtained from the patients by indirect immunoflurescence assays. Our data presented that: (1) None of granulomatous tissues was found to have Bb DNA in 23 tissue samples. (2) Thirty of 55 (54.6%) patients with sarcoidosis were found antibodies to Bb positive, in contrast, six of 60 (10%) normal subjects had antibodies against Bb, the positive rate was remarkably higher in patient group than that in healthy group (P < 0.005). The results suggest that Bb might not be the causative agent of sarcoidosis, the elevated titres of serum antibodies against Bb in patients with sarcoidosis is a nonspecific response.

[Factors affecting prognosis of papillary thyroid carcinoma with bilateral cervical lymph node metastases]

One hundred thirty nine cases of papillary thyroid carcinoma with bilateral lymph node metastases were reviewed. They were surgically treated at the Cancer Hospital of Shanghai Medical University in the years from 1956 through 1990. There were 73 men and 66 women with a median age of 35 (range 11-70) years. The median follow-up period was 11 years. Kaplan-Meier survival curves were calculated for the population. The overall survival rate was 94.7% at 5 years, 85.9% at 10 years, and 82.3% at 15 years. In univariate analysis, factors influencing prognosis are age at diagnosis, tumor size, extrathyroidal invasion, residual tumor and thoroughness of excision. When Cox proportional risk model was applied to analyze the survival data, factors of survival significance are the age at diagnosis and thoroughness of excision.

[The application of regional excision of parotid gland in the treatment of Warthin tumors]

The regional excision of parotid gland (resection of the tumor with its surrounding glands) was applied in 54 cases with Warthin tumor. Its role was evaluated by follow-up study, iodine-starch test (Minor test), radionuclide scintigraphy, and comparison with superficial parotidectomy. The results showed that regional excision had the following advantages: shortening the time of operation, decreasing the injury of facial nerve, avoiding the facial deformity and Frey syndrome, and reserving the function of parotid glands. The theoretical basis, indications, and some considerable questions during the operation were discussed.

[Comparisons of three simple nutritional assessments applied to patients with oral and maxillofacial malignancies]

Combined subjective and objective nutritional assessment (SNA), concise nutritional assessment (CNA), general nutritional status score (GNS), and subjective global assessment of nutritional status (SGA) were applied to assess the nutritional status of 127 patients with oral and maxillofacial malignancies. On this base SNA was used as a standard nutritional assessment to compare the validities of CNA, GNS, and SGA. The results showed: 1) the total agreement rate of CNA (88.2%) was higher than that of GNS (78.0%) and SGA (78.7%); 2) the false positive rate (9.9%) and false negative rate (15.2%) of CNA was lower than that of GNS (17.3%, 30.4%) and SGA (14.8%, 32.6%); 3) the diagnosis index of CNA (74.9%) was significantly (P < 0.05) higher than that of GNS (52.3%) and SGA (52.6%); and 4) the nutritional parameters of CNA were measured by instruments with little man-made errors. These results indicate that CNA can be regarded as the best nutritional assessment for the patients in oral and maxillofacial surgery.

[The relationship of function and pathology of submandibular gland with sialolithiasis]

Submandibular glands with sialolithiasis are analysed histopathologically. The formation of the calculi of the submandibular glands may be related to the sialoadentitis and to the changes of saliva composition. Mineralization of the organic matrix may be one of the cause of calculus formation. By comparison of the glandular function with the pathology of the gland, it shows that the reduction of glandular function is associated with the severity of grandular inflammation. When function index is normal, grandular inflammation is in the Stage I or II, while it decreases or zero, grandular inflammation is in the Stage III or IV. Glandular function index may predict the severity of grandular inflammation.

Leishmania donovani possess a NADPH-dependent alkylglycerol cleavage enzyme

Leishmania parasites possess an abundance of ether-linked hydrocarbons as components of phospholipids and glycosylphosphatidylinositol anchors of glycoproteins and polysaccharides, including important surface molecules such as lipophosphoglycan (LPG) and glycosylinositolphospholipids (GIPLs). Cleavage of the ether bond is an important feature in the turnover pathway of alkylglycerols. In mammals, ether lipid cleavage activity requires a pteridine cofactor (H4 biopterin), suggesting the potential for linkage between the unusual Leishmania pteridine metabolic pathways and lipid metabolism. In this study, we partially purified and characterized an activity in L. donovani capable of cleaving the ether lipid 1-O-alkyl[3H]glycol. Unlike the mammalian enzyme but like that of Tetrahymena, the Leishmania enzyme required NADPH rather than H4-biopterin. The use of divergent cofactors by the parasite and mammalian enzymes may provide a basis for the design of anti-parasitic drugs targeting ether-linked lipid metabolism.

[An experimental study on BMP gene expression in vivo]

The authors inserted the full length BMP-1 cDNA into Xbal-treated pRc/RSV plasmid via ligation, resulting in construction of pRc/RSV/BMP-1 eukaryotic expression vector. The validity of the reconstructed vector was confirmed by the restriction map. Then more reconstructed plasmids were extracted. According to the general principle of gene therapy, 100 micrograms of pRc/RSV/BMP-1 plasmid was transferred into a Balb/c mouse quadriceps by implantation under anaesthesia respectively. After 3 weeks, the BMP gene expression was detected in the mouse muscles by histoimmunochemistry.

[Detection of Borrelia burgdorferi DNA in granulomatous tissues from patients with sarcoidosis using polymerase chain reaction in situ technique]

OBJECTIVE

To investigate the correlation between sarcoidosis and Borrelia burgdorferi (Bb) infection.

METHODS

Flagella DNA of Bb were detected in 23 tissue speciments from patients with confirmed sarcoidosis using polymerase chain reaction in situ technique (in situ PCR) and the antibodies to Bb were examined in 55 serum samples obtained from the patients by indirect immunoflurescence assays.

RESULTS

(1) None of granulomatous tissues was found to have Bb DNA in 23 tissue samples. (2) 30 of 55 (54.6%) patients with sarcoidosis were found antibodies to Bb positive, in contrast, six of 60 (10%) normal subjects had antibodies against Bb, the positive rate was remarkably higher in patient group than that in healty group (P < 0.005).

CONCLUSIONS

Bb might not be the causative agent of sarcoidosis, the elevated titres of serum antibodies against Bb in patients with sarcoidosis is a nonspecific response.

Association between NM23-H1 gene expression and metastasis of human uveal melanoma in an animal model

PURPOSE

To evaluate the role of nm23 gene expression in the development of metastases of human uveal melanomas in an animal model.

METHODS

Seven human uveal melanoma cell lines and two murine skin melanoma cell lines were subjected to Northern blot analysis for the detection of nm23-H1 mRNA and to immuno-histochemistry to detect nm23 antigen. Each tumor cell line was transplanted intracamerally into nude mice, and the metastatic behavior was evaluated by histopathologic analysis of the livers and by determining host survival times.

RESULTS

There was a strong inverse correlation between the levels of nm23 mRNA expression and nm23 antigen expression and the development of metastases of all seven human uveal melanomas and both murine skin melanomas transplanted intracamerally. Host survival time also was correlated with the degree of nm23 gene expression.

CONCLUSIONS

The expression of nm23 mRNA and nm23 antigen in human uveal melanomas is correlated closely with reduced metastatic behavior in experimental animals and may serve as a sensitive prognostic indicator of malignancy and survival in patients with uveal melanomas.

Sst2, a negative regulator of pheromone signaling in the yeast Saccharomyces cerevisiae: expression, localization, and genetic interaction and physical association with Gpa1 (the G-protein alpha subunit)

Sst2 is the prototype for the newly recognized RGS (for regulators of G-protein signaling) family. Cells lacking the pheromone-inducible SST2 gene product fail to resume growth after exposure to pheromone. Conversely, overproduction of Sst2 markedly enhanced the rate of recovery from pheromone-induced arrest in the long-term halo bioassay and detectably dampened signaling in a short-term assay of pheromone response (phosphorylation of Ste4, Gbeta subunit). When the GPA1 gene product (Galpha subunit) is absent, the pheromone response pathway is constitutively active and, consequently, growth ceases. Despite sustained induction of Sst2 (observed with specific anti-Sst2 antibodies), gpa1delta mutants remain growth arrested, indicating that the action of Sst2 requires the presence of Gpa1. The N-terminal domain (residues 3 to 307) of Sst2 (698 residues) has sequence similarity to the catalytic regions of bovine GTPase-activating protein and human neurofibromatosis tumor suppressor protein; segments in the C-terminal domain of Sst2 (between residues 417 and 685) are homologous to other RGS proteins. Both the N- and C-terminal domains were required for Sst2 function in vivo. Consistent with a role for Sst2 in binding to and affecting the activity of Gpa1, the majority of Sst2 was membrane associated and colocalized with Gpa1 at the plasma membrane, as judged by sucrose density gradient fractionation. Moreover, from cell extracts, Sst2 could be isolated in a complex with Gpa1 (expressed as a glutathione S-transferase fusion); this association withstood the detergent and salt conditions required for extraction of these proteins from cell membranes. Also, SST2+ cells expressing a GTPase-defective GPA1 mutant displayed an increased sensitivity to pheromone, whereas sst2 cells did not. These results demonstrate that Sst2 and Gpa1 interact physically and suggest that Sst2 is a direct negative regulator of Gpa1.

[Traumatic facial nerve injury in rabbits: a quantitative pathologic study]

Six kinds of facial nerve injury in 136 facial nerves of 68 rabbits were studied by quantitative pathology. The ratio of intrafascicular axon crossing and the ratio of intrafascicular area can reflect the extent of the lesions for non-cut injury (exposure, compression, stretch and crush) effectively. However, the ratio of mesial to distal intrafascicular area should be combined for the evaluation of cut injury (division and anastomosis). The mean optical density (F1), axon area (F13), and homogeneous degree (F49) can reflect quantitatively the form and extent of the single axon lesion and its content. The morphologic parameter (F10) can reflect the change of axon morphology. The results of quantitative pathologic study support the histopathologic study, and provide additional knowledge about the progress of serial axon lesions.

A dynamic and quantitative study of pattern visual evoked potentials and gamma-aminobutyric acid neurones in the lateral geniculate nucleus and the visual cortex of monocular deprivation cats

PURPOSE

To assess the effects of monocular lid closure during critical period on cortical activity.

METHOD

Pattern visual evoked potentials (PVEP) of the normal and the monocular deprivation (MD) cats were dynamically measured and the number of gammaaminobutyric acid immunopositive (GABA-IP) neurones of the area 17 of the visual cortex and the lateral geniculate nucleus (LGN) was quantitatively compared by using immunohistochemical method (ABC).

RESULTS

The amplitude of the N1-P1 attenuated in deprived eyes (DE), NE/DE at postnatal week (PNW) 7-8 (P < 0.05), NE/DE at PNW 15-16 (P < 0.01); while P1 latency delayed, NE/DE at PNW 7-8 (P > 0.05), NE/DE at PNW 15-16 (P< 0.05). The numbers of GABA-IP neurones in layer A1 of the ipsilateral LGN and in layer A of the contralateral LGN, compared to those in the corresponding normal laminae, were not significant at PNW 7-8 and PNW 11-12 (P > 0.05), while in the same cats a reduction in the number of GABA-IP neurones was found in layer IV of area 17 at PNW 11-12 (P < 0.05). However, with longer survival of 3-4 weeks in duration, the numbers of GABA-IP neurones in the deprived laminae of LGN were remarkably reduced (P < 0.05).

CONCLUSIONS

The amplitude of N1-P1 components is sensitive to the effects of monocular deprivation. Monocular deprivation in cats during critical period leads to dramatic changes of the number of GABA-IP neurones in the LGN and cortical layer IV receiving inputs from the deprived eye in cats. The deprivation-induced reduction in GABA-IP neurones is delayed in the LGN compared with the visual cortex. PVEP of the MD cats is consistent with the damage of its GABA system in visual cortex.

Protective effect of interleukin-1 receptor antagonist on oleic acid-induced lung injury

OBJECTIVE

To observe the changes of interleukin-1 (IL-1), nitric oxide (NO) and nitric oxide synthase (NOS) in mice with oleic acid-induced acute lung injury (ALI) and the protective effects of interleukin-1 receptor antagonist (IL-1ra).

MATERIAL AND METHODS

Male Kunming mice were divided into control, oleic acid and IL-1ra groups. The control group mice were injected saline; the oleic acid group mice were injected oleic acid (0.2 ml/kg): and the IL-1ra group mice were injected the IL-1ra (20 mg/kg). Lung index, lung wet-to-dry weight ratio, and total protein, cell analysis, nitric oxide measurement, NOS activity in BALF, lung pathology examination were made after an hour of administration of drug.

RESULTS

Preadministration of IL-1ra to the mouse with ALI decreased the lung index, lung wet-to-dry weight ratio and leakage of protein from pulmonary capillary, elevated PaO2, and attenuated lung histologic injury. It was found that in bronchoalveolar lavage fluid (BALF), NO amount and lung NOS activity increased in oleic acid group, BALF NO amount and lung NOS activity decreased obviously after given IL-1ra.

CONCLUSIONS

This study demonstrated the protective effect of IL-1ra on oleic acid-induced lung injury, NO may participate in the pathological process of lung injury.

Recognizing post-polio syndrome

The disorder consists of fatigue accompanied by new muscle weakness and muscle pain or, for patients whose acute polio had included bulbar involvement, new difficulty in swallowing or change in voice. The epidemiology remains unclear, fueling anxiety among polio survivors. Yet its course is not drastically progressive, and impairment is usually limited.

AcrAB efflux pump plays a major role in the antibiotic resistance phenotype of Escherichia coli multiple-antibiotic-resistance (Mar) mutants

Multiple-antibiotic-resistance (Mar) mutants of Escherichia coli are resistant to a wide variety of antibiotics, and increased active efflux is known to be responsible for the resistance to some drugs. The identity of the efflux system, however, has remained unknown. By constructing an isogenic set of E. coli K-12 strains, we showed that the marR1 mutation was incapable of increasing the resistance level in the absence of the AcrAB efflux system. This experiment identified the AcrAB system as the major pump responsible for making the Mar mutants resistant to many agents, including tetracycline, chloramphenicol, ampicillin, nalidixic acid, and rifampin.

[Enhancing immunogenicity of pres antigen of hepatitis B virus by fusing genetically it with interleukin-2]

OBJECTIVE

To combine the bioactivities of human interleukin-2 (IL-2) with entire preS antigen of hepatitis B virus (HBV), and search for specific immunotherapeutic agent against chronic hepatitis B.

METHODS

A chimeric gene composed of preS gene from HBV DNA and human IL-2 cDNA was constructed by using polymerase chain reaction and genetic engineering methods, and a novel type of chimeric protein (IL-2-preS) was expressed with high efficiency in E. coli transformed by the chimeric gene clone.

RESULTS

It was confirmed that the chimeric protein retained the full bioactivities of natural IL-2 and preS molecules, such as maintaining CTLL cells to proliferate, with the specific activity being about 10(7)u/mg protein, and binding with monoclonal antibodies against preS1 and preS2 and polymerized human serum albumin (PHSA), etc. It was shown that the titer of antibody against preS antigen in mice induced by IL-2-preS was 9, 11 and 13 times more than those induced by a mixture of IL-2 with preS antigen, MS-2-preS chimeric protein and preS antigen alone, respectively.

CONCLUSION

IL-2-preS potentiates immunogenecity of preS antigen and enhances immune responses of human bodies against preS antigen. In addition, IL-2-preS is of double targetting effect in human bodies, and may be used as a new generation of immunotherapeutic agent for chronic hepatitis B and hepatocellular carcinoma.

The local repressor AcrR plays a modulating role in the regulation of acrAB genes of Escherichia coli by global stress signals

Genes acrAB encode a multidrug efflux pump in Escherichia coli. We have previously reported that transcription of acrAB is increased under general stress conditions (i.e. 4% ethanol, 0.5 M NaCl, and the stationary phase in Luria-Bertani medium). In this study, lacZ transcriptional fusions and an in vitro gel mobility shift assay have been utilized to study the mechanisms governing the regulation of acrAB. We found that a closely linked gene, acrR, encoded a repressor of acrAB. Nevertheless, the general stress conditions increased transcription of acrAB in the absence of functional AcrR, and such conditions surprisingly increased the transcription of acrR even more strongly than that of acrAB. These results suggest that the general-stress-induced transcription of acrAB is primarily mediated by global regulatory pathway(s), and that one major role of AcrR is to function as a specific secondary modulator to fine tune the level of acrAB transcription and to prevent the unwanted overexpression of acrAB. To our knowledge, this represents a novel mechanism of regulating gene expression in E. coli. Evidence also suggests that the up-regulation of acrAB expression under general stress conditions is not likely to be mediated by the known global regulators, such as MarA or SoxS, although elevated levels of these proteins were shown to increase the transcription of acrAB.

Regulation of gap junction intercellular communication by pH in MC3T3-E1 osteoblastic cells

Gap junction intercellular communication (GJIC) may be related to coordinating the function of osteoblasts during bone mineralization. Since an alkaline pH supports mineral deposition while an acidic pH promotes mineral dissolution, it was investigated whether GJIC is altered by changes in extracellular pH (pHo) Functional GJIC was assessed by fluorescent dye transfer after microinjection, and connexin protein abundance was examined by immunoprecipitation and immunoblotting in MC3T3-E1 cells, a model of osteoblast-like cells. The percent of cells coupled by GJIC was found to be 40.7% (24 of 59 injected cells) at pH 6.9, 72.2% (26 of 36) at pH 7.2, and 92.8% (26 of 28) at pH 7.6. A decrease in GJIC was detectable by 30-60 minutes of exposure to a pHo of 6.9. Decreased gap junction communication was also found in cells after 3, 8, and 24 h of incubation in a bicarbonate-CO2 system at an ambient pH of 6.9. Connexin protein abundance experiments showed that at after exposure to a pH of 6.9 for 2.75 h, the specific band(s) at 41-43 kD were fainter compared with these same band(s) at pH 7.2 and 7.6. There was no significant difference in band densities at pH 7.2 and 7.6. Determination of intracellular pH (pHi) showed that it was similar to pHo after 2.75 h of incubation at each ambient pH. When pHi was clamped at 6.9 or 7.2, there was a time-dependent decrease in the gap junction coupling frequency at a pHi of 6.9 when pHo was 7.2. Steady-state mRNA levels were decreased at pHo 6.9 but were unchanged at either pHo 7.2 or 7.6. Our conclusions are that (1) longer incubations ( > or = 2.75 h) at low pHo decrease GJIC which in part may be due to a decrease in connexin protein abundance perhaps as a result of a decrease in connexin steady-state mRNA expression; (2) GJIC inhibition or augmentation found at low and high pHo, respectively, suggests that gating of the GJ channel by pH may also occur; (3) pho-induced alterations in GJIC in the MC3T3-E1 osteoblastic model are related to concomitant changes in pHi.

Neuronal expression of human immunodeficiency virus type 1 env proteins in transgenic mice: distribution in the central nervous system and pathological alterations

It is now well documented that human immunodeficiency virus type 1 (HIV-1) induces encephalopathy in patients with AIDS. In vitro studies have implicated the envelope protein (gp120) as a factor which causes neuronal death. To better evaluate the role and elucidate the mechanisms of gp120 neurotoxicity, we have developed transgenic mice carrying a segment of the HIV-1 genome that expresses the viral gp160 protein under the control of the human neurofilament light gene promoter. In two separate lines of transgenic mice, the Env protein was found to be expressed in several nuclei of the brain stem and in the anterior horns of the spinal cord. The two lines showed identical patterns of Env expression. Neuropathological evaluation revealed numerous abnormal dendritic swellings in the immunostained motor neuron structures. Large and numerous neuritic swellings were also prominent in the nucleus gracilis and in the gracilis and cuneate fascicles. In addition, reactive astrocytosis was observed in several immunoreactive areas of the central nervous system. These transgenic mice offer a unique model to further investigate the role of HIV-1 Env protein in neuronal toxicity and to help elucidate the mechanisms that are involved.

[Pathological studies on the anti-invasive character of IL-6 gene transfected leukemia cells]

FBL-3 Leukemia cells transfected with IL-6 gene were expanded in vitro and inoculated into C57BL/6 mice subcutaneously. Tumor growth was observed and histologic analyses of the tumors in situ and the liver, spleen and bone marrow were performed at 14, 21, 28 and 35 days after inoculation. The mice inoculated with wild-type FBL-3 leukemia cells were used as the control. We found that the tumor invasiveness in the mice inoculated with FBL-3-IL-6+ occurred later than in the control group. The survival time of experimental mice was longer than in the control mice. The results demonstrated that inoculation of IL-6 high-secreting FBL-3 inhibited invasiveness of the leukemia cells, suggesting that the IL-6 gene transfected FBL-3 cells can be used as a vaccine to treat leukemia. The mechanism of the anti-invasiveness of IL-6 gene transfected leukemia cells needs further study.

Transforming growth factor-beta down-regulates major histocompatibility complex class I antigen expression and increases the susceptibility of uveal melanoma cells to natural killer cell-mediated cytolysis

Intraocular melanomas, especially those of the anterior segment, reside within an immunologically privileged milieu. Aqueous humour contains a variety of immunomodulatory factors that are believed to contribute to ocular immune privilege. Among these is transforming growth factor-beta (TGF-beta), which has been shown to down-regulate major histocompatibility complex (MHC) class I antigens on normal cells. Since the susceptibility of tumour cells to natural killer (NK) cell-mediated lysis is inversely correlated with the expression of MHC class I antigens, tumour cells exposed to TGF-beta might be expected to experience enhanced susceptibility to NK-mediated killing. This was examined by incubating two human uveal melanoma cell lines in the presence of TGF-beta and evaluating the expression of MHC class I antigen and susceptibility to NK cell-mediated lysis. OCM1 and OCM8 melanoma cells constitutively express high levels of class I antigen (85-90% positive) and low susceptibility to NK-mediated lysis in vitro (3-8%). Incubation with TGF-beta produced a significant reduction in class I antigen expression (52-62%) and a proportional increased susceptibility to NK cell-mediated cytolysis (17%). Analogous effects were found using a human uveal melanoma cell line (OCM3) that constitutively expresses low amounts of class I (< 5% positive) and high NK susceptibility (35% lysis). Stimulation of class I antigen expression by incubation with interferon-gamma resulted in a sharp increase in class I expression (80% positive) and a comparable diminution in susceptibility to NK cell-mediated lysis (< 10%). The results indicate that TGF-beta, at concentrations found in the aqueous humour, can significantly alter MHC class I antigen expression and the susceptibility of ocular melanoma cells to NK cell-mediated cytolysis.

Abnormal perikaryal accumulation of neurofilament light protein in the brain of mice transgenic for the human protein: sequence of postnatal development

Adult mice transgenic for the human form of neurofilament light protein display abnormal perikaryal immunoreactivity for this protein in many regions of the CNS and notably the thalamus. To determine the sequence of development of these anomalies, we have compared normal and transgenic mice of different postnatal ages (P0-P70), using immunocytochemistry with primary antibodies recognizing both murine and human sequence of neurofilament light protein (NR-4) or the human form only (DP5-1-12). In normal mouse brainstem, several nuclei displayed immunoreactive perikarya at P0. The number of these perikarya culminated at P10, followed by a general decrease, some nuclei having lost all perikaryal immunostaining in adults. In transgenic mouse brainstem, the distribution of perikaryal immunoreactivity already resembled at P0 that of P10 in normal mouse, and remained unchanged in adults. Differences between normal and transgenic mice were even more pronounced in the forebrain. Some nuclei of normal mouse basal forebrain that were weakly immunopositive at P10 or P20, but no longer in adults, were already labeled at P0 and remained so or became more intense at later stages in transgenic mice. In the thalamus of normal mouse, perikaryal labeling was faint, confined to a few nuclei, and detected only transiently at P10, whereas in transgenics, it was already observed in some nuclei at P0, increased in intensity and extended to other nuclei at P10, and persisted thereafter. Strongly immunoreactive, inflated perikarya with excentric nuclei were prominent in these thalamic nuclei at P20, and even larger in size at P70. In the cerebral cortex of normal mice, layers II-III and layer V of many cytoarchitectonic areas showed immunoreactive cell bodies at P10, a distribution which became gradually restricted to the parietal cortex in adults. In transgenic mice, immunopositive cortical cell bodies were first detected at P3, filled layers II-III of numerous cortical areas at P10, and then rapidly decreased in number to approach the adult pattern at P20. In the cortex as well as thalamus of P10 transgenic mice, differences between the patterns of cellular staining with clones NR4 and DP5-1-12 antibodies indicated that both the murine and human proteins were accumulated in these neurons. Thus, neurofilament light protein accumulation in the transgenic mouse brain generally involved neurons displaying perikaryal immunoreactivity for the protein at least at some point during normal postnatal development.(ABSTRACT TRUNCATED AT 400 WORDS)

Phosphorylation and localization of Kss1, a MAP kinase of the Saccharomyces cerevisiae pheromone response pathway

Kss1 protein kinase, and the homologous Fus3 kinase, are required for pheromone signal transduction in Saccharomyces cerevisiae. In MATa haploids exposed to alpha-factor, Kss1 was rapidly phosphorylated on both Thr183 and Tyr185, and both sites were required for Kss1 function in vivo. De novo protein synthesis was required for sustained pheromone-induced phosphorylation of Kss1. Catalytically inactive Kss1 mutants displayed alpha-factor-induced phosphorylation on both residues, even in kss1 delta cells; hence, autophosphorylation is not obligatory for these modifications. In kss1 delta fus3 delta double mutants, Kss1 phosphorylation was elevated even in the absence of pheromone; thus, cross-phosphorylation by Fus3 is not responsible for Kss1 activation. In contrast, pheromone-induced Kss1 phosphorylation was eliminated in mutants deficient in two other protein kinases, Ste11 and Ste7. A dominant hyperactive allele of STE11 caused a dramatic increase in the phosphorylation of Kss1, even in the absence of pheromone stimulation, but required Ste7 for this effect, suggesting an order of function: Ste11-->Ste7-->Kss1. When overproduced, Kss1 stimulated recovery from pheromone-imposed G1 arrest. Catalytic activity was essential for Kss1 function in signal transmission, but not for its recovery-promoting activity. Kss1 was found almost exclusively in the particulate material and its subcellular fractionation was unaffected by pheromone treatment. Indirect immunofluorescence demonstrated that Kss1 is concentrated in the nucleus and that its distribution is not altered detectably during signaling.

Effect of alteration of the heterocyclic nucleus of ILV on its isoform selectivity for PKC. Palladium catalyzed route to benzofuran analogues of ILV

A palladium catalyzed route for the preparation of several benzofuran analogues of the PKC activator indolactam V (ILV) is described together with the ability of these compounds to activate the isoforms of PKC. The benzofuran analogues of ILV are shown to activate PKC with a slightly different pattern of isotype selectivity than ILV or 7-n-octyl-ILV. Moreover, in an examination of the effect of stereochemistry at the C-14 center of the teleocidins on PKC binding activity, a clear preference for R-stereochemistry at the C-14 center was found, thus providing additional verification of previously published structural correlations between the families of PKC activators.

Tissue-type plasminogen activator-induced invasion and metastasis of murine melanomas

The role of tissue-type plasminogen activator (tPA) in the 'spontaneous' as well as 'experimental' metastasis of ocular melanomas in mice was evaluated by transfecting the D5.1G4 murine melanoma cell line that possesses low metastatic activity and low tPA activity with a full length cDNA encoding human tPA. For comparison, a highly metastatic melanoma cell line (Queen's) that constitutively expresses high tPA production, was transfected with a cDNA coding for human plasminogen activator inhibitor type 1 (PAI-1). Unlike non-transfected controls, transfected D5.1G4 melanoma cells expressed high levels of tPA and produced extensive pulmonary metastases following intravenous injection. By contrast, PAI-1 transfected Queen's melanoma cells expressed low tPA activity and displayed significantly reduced metastatic potential compared with nontransfected controls. Moreover, PAI-1 transfected Queen's melanoma cells did not metastasize from the eye while nontransfected parental cells produced extensive spontaneous metastases. Expression of tPA activity in transfected and nontransfected cell lines was completely blocked by an anti-tPA antibody. This antibody significantly inhibited the organ localization and frequency of lung metastases of both Queen's and tPA-transfected D5.1G4 melanomas. This study demonstrates that tPA is involved in the metastasis of murine intraocular melanomas.

Efficacy of tumor-infiltrating lymphocytes in the treatment of hepatic metastases arising from transgenic intraocular tumors in mice

PURPOSE

The purpose of this study was to determined if tumor-infiltrating lymphocytes (TIL) isolated from transgenic intraocular tumors were capable of preventing the development of spontaneous hepatic metastases.

METHODS

Tumor-infiltrating lymphocytes were isolated from intraocular tumors in immunocompetent mice and were examined for cytolytic activity in vitro. The antigenic phenotypes of the TIL were determined by in situ immunohistology. Cultured TIL were transferred adoptively to immunoincompetent, intraocular, tumor-bearing recipients to determine the efficacy of TIL in preventing spontaneous liver metastases.

RESULTS

Cultured TIL displayed remarkable cytolytic activity in vitro and antimetastatic properties after adoptive transfer into immunoincompetent, athymic nude mice and anti-CD4/CD8-treated euthymic FVB/N mice. Hepatic metastases developed in only 2 of 10 athymic nude mice that subsequently received TIL, whereas metastases developed in all 10 control mice. Similar results were found in anti-CD4/CD8-treated FVB/N mice. Hepatic metastases did not develop in any of the 10 mice treated with TIL, whereas extensive metastatic foci developed in all 10 untreated FVB/N control mice. The efficacy of TIL therapy was manifested also by significant prolongation of host survival times.

CONCLUSIONS

Tumor-infiltrating lymphocytes isolated from intraocular tumors can be expanded in vitro and can exert antimetastatic effects in vivo.

Genes acrA and acrB encode a stress-induced efflux system of Escherichia coli

Defined mutations of acrA or acrB (formerly acrE) genes increased the susceptibility of Escherichia coli to a range of small inhibitor molecules. Deletion of acrAB increased susceptibility to cephalothin and cephaloridine, but the permeability of these beta-lactams across the outer membrane was not increased. This finding is inconsistent with the earlier hypothesis that acrAB mutations increase drug susceptibility by increasing the permeability of the outer membrane, and supports our model that acrAB codes for a multi-drug efflux pump. The natural environment of an enteric bacterium such as E. coli is enriched in bile salts and fatty acids. An acrAB deletion mutant was found to be hypersusceptible to bile salts and to decanoate. In addition, acrAB expression was elevated by growth in 5 mM decanoate. These results suggest that one major physiological function of AcrAB is to protect E. coli against these and other hydrophobic inhibitors. Transcription of acrAB is increased by other stress conditions including 4% ethanol, 0.5 M NaCl, and stationary phase in Luria-Bertani medium. Finally, acrAB expression was shown to be increased in mar (multiple-antibiotic-resistant) mutants.

[Hemofiltration ameliorating reperfusion injury after complete cerebral ischemia: an experimental study]

The effects of hemofiltration on cerebral resuscitation were studied by using resuscitation model of potassemia-induced cardiac arrest and cardiopulmonary bypass. Sixteen rabbits were divided into control group (CG) and hemofiltration group (HFG). Blood lactic acid, lipid peroxidant (LPO), serum iron, middle molecular substance (MMS) were determined. Neurologic deficit score (NDS) system was used to evaluate neurologic function. The level of blood lactic acid was increased in both CG and HFG. It was higher in CG than in HFG (P > 0.05). Serum iron was increased in CG, however, it was decreased in HFG. The difference between the two groups was significant (P < 0.01). LPO was increased significantly in CG and there was no obvious changes in HFG. MMS was increased gradually during reperfusion in CG, whereas it was decreased in HFG. There was significant difference in the corresponding times of the two groups. NDS of CG was higher than that of HFG (32 +/- 12 vs 18 +/- 10) (P < 0.01). These data demonstrate that hemofiltration is able to eliminate ischemic and reperfusional toxic products quickly. Additionally, free iron, agonist factor of catalyzing free radical reaction, does not increase because free radicals and lactic acid are eliminated quickly, inhibiting free radical tissue injury and improving cerebral resuscitation.

Successful immunization against Acanthamoeba keratitis in a pig model

The feasibility of inducing protective immunity to Acanthamoeba keratitis was tested in a pig model. Experiments were designed to determine if ocular infection with Acanthamoeba trophozoites would elicit protection against reinfection. Additional experiments examined whether injection of parasite antigens either intramuscularly, subconjunctivally, or by both routes would induce immunity. Therefore, four groups of animals were examined: (a) pigs that had resolved a primary corneal infection with Acanthamoeba; (b) pigs immunized intramuscularly; (c) pigs immunized subconjunctivally; and (d) pigs immunized intramuscularly and subconjunctivally. Animals were subsequently challenged with parasite-laden soft contact lenses and observed clinically for the appearance of Acanthamoeba keratitis. Acanthamoeba-specific serum antibody titers and blastogenic responses of peripheral blood lymphocytes were determined weekly. The results indicated that intramuscular injection of Acanthamoeba antigens failed to protect against ocular infection even though hosts developed high titers of IgG antibodies and displayed lymphocyte blastogenic responses to parasite antigens. Ocular infection alone failed to stimulate immunity in any of the animals. By contrast, 50% of the hosts immunized subconjunctivally were protected against corneal disease, and 100% of the animals immunized by a combination of intramuscular and subconjunctival administration of parasite antigens were completely protected against two separate ocular challenges with infectious parasites. Protection did not correlate with either IgG antibody titers or blastogenic potentials of peripheral blood lymphocytes. Interestingly, ocular infection alone failed to stimulate immunity to subsequent ocular challenge with infectious parasites. Thus, administration of parasite antigen via the subconjunctival route can protect against Acanthamoeba keratitis.

CNS distribution and overexpression of neurofilament light proteins (NF-L) in mice transgenic for the human NF-L: aberrant accumulation in thalamic perikarya

Light microscopic immunocytochemistry with monoclonal antibodies recognizing both murine and human light neurofilament proteins (mNF-L and hNF-L) or hNF-L only was used to examine the distribution of NF-L in the CNS of adult mice, normal or transgenic for the human gene. In normal mice, major fiber bundles were immunoreactive to the first antibody, with few exceptions such as the internal capsule, anterior commissure, and corpus callosum. Strong immunoreactivity was also present in the perikarya of motoneurons in the spinal cord and brainstem, as well as in other brainstem nuclei. Faint cell body staining was visible in layers II, III, and V of the parietal cortex and layers V and VI of the retrosplenial cingulate cortex. In transgenic mice, all forebrain as well as brainstem fiber tracts were intensely immunoreactive to both antibodies. Cell body staining was more intense than in normal mouse and involved additional forebrain and brainstem regions, including extended areas of cerebral cortex. Abnormal cell body labeling was particularly striking in several thalamic nuclei, where numerous darkly stained perikarya were considerably enlarged by accumulated immunoreactive material and exhibited eccentric and fragmented nuclei. At the electron microscopic level, these perikarya were filled with disarrayed filaments displacing all other organelles against the cytoplasmic membrane. Such aberrant accumulation of NF-L was presumably the result of an overexpression in selective subpopulations of CNS neurons. It was compatible with prolonged survival of the animal and could provide a new experimental model of neurodegenerative disease.

Relationship between natural killer cell susceptibility and metastasis of human uveal melanoma cells in a murine model

PURPOSE

The purpose of this study was to determine the susceptibility of human uveal melanoma cells to in vitro and in vivo natural killer (NK) cell-mediated cytolysis and to determine if NK cells influence metastasis from the eye.

METHODS

Four human uveal melanoma cell lines and one melanoma cell line derived from a metastatic lesion from a patient with uveal melanoma were tested for in vitro and in vivo NK cell-mediated lysis in a mouse model. Major histocompatibility complex (MHC) class I antigen expression was evaluated by flow cytometry. The role of NK cells in controlling the metastasis of uveal melanoma cells from the eye to the liver was examined in nude mice.

RESULTS

Sensitivity to in vitro and in vivo lysis by human and murine NK cells was correlated with reduced expression of MHC class I antigens. Uveal melanoma lines expressing normal MHC class I antigen expression were insensitive to NK cell-mediated lysis, both in vitro and in vivo. Metastasis of uveal melanoma cells was inhibited by NK cell activity because disruption of in vivo NK function produced a sharp increase in the spontaneous metastasis of intraocular melanomas in nude mice.

CONCLUSIONS

There is considerable variation in the susceptibility of human uveal melanomas to NK cell-mediated cytolysis. Susceptibility is closely correlated with reduced expression of MHC class I antigen expression. Disruption of NK cell function significantly increases the development of hepatic metastases from human uveal melanoma cells.

Efflux pumps and drug resistance in gram-negative bacteria

The outer membrane of Gram-negative bacteria can only slow down the influx of lipophilic inhibitors, and so these bacteria need active efflux pumps of broad specificity to survive. Pumps such as the Escherichia coli Acr system and its homologs make Gram-negative bacteria resistant to dyes, detergents and antibiotics.