Molecular evidence that most but not all carcinosarcomas of the uterus are combination tumors

The pathogenesis of carcinosarcoma is still a subject of controversy. In the present study, molecular techniques were applied to determine the pathogenesis of uterine carcinosarcomas. The patterns of chromosome X inactivation were analyzed, targeting a portion of exon 1 of the human androgen receptor (HUMARA) in malignant epithelial and mesenchymal components. The presence of p53 and K-ras mutations were also analyzed. H&E-stained sections of paraffin-embedded, formalin-fixed tissues were microdissected to obtain both epithelial and nonepithelial lesions from 25 carcinosarcomas, and DNAs were extracted by proteinase K digestion. Following treatment with methylation-sensitive restriction endonuclease (HhaI or HpaII), PCR amplification was performed using nested primers targeted to the HUMARA locus. Mutations in the p53 gene and K-ras gene were found in eight (32%) and six (24%) tumors, respectively. The patterns of chromosome X inactivation were different between the carcinomatous and sarcomatous components of three carcinosarcomas, indicating that these three tumors represent collision tumors. By contrast, the patterns of chromosome X inactivation, K-ras sequence, and p53 sequence were identical in both carcinomatous and sarcomatous components in 21 carcinosarcomas, indicating that these 21 tumors represent combination tumors. One case produced equivocal results that precluded determination of whether it represented a collision or combination tumor. These observations show that although most carcinosarcomas are combination tumors, some develop as collision tumors. The determination of histogenesis in individual cases of carcinosarcoma using molecular markers may be worthwhile, because the result could help predict the prognosis of individual cases and help guide clinical management.

Clonal analysis of high-grade squamous intra-epithelial lesions of the uterine cervix

We previously reported that invasive squamous cell carcinomas of the uterine cervix are of monoclonal composition. In the current study, we extended our previous work to determine the clonal composition of cases of high-grade squamous intra-epithelial lesion (HSIL). Clonal analysis targeting the HUMARA locus was performed on cervical tissue from 9 cases, 8 showing heterozygosity at the HUMARA locus and being, therefore, informative for clonality analysis. Uterine cervices were cut into 12 blocks, fixed with formalin and embedded in paraffin, and DNA was extracted from targeted lesions of each block. A total of 30 samples of cervical intra-epithelial neoplasia 3 (CIN3) (14 samples of carcinoma in situ and 16 samples of severe dysplasia) and 1 sample of CIN2 (moderate dysplasia) were analyzed. Monoclonal composition of the lesions was demonstrated in 30/30 cases of CIN3. Polyclonal composition was seen in the single case of CIN2. In 6 uterine cervices, in which dysplastic lesions were present in more than 3 blocks, the pattern of X-chromosome inactivation was the same in all lesions, suggesting that these individual lesions were derived from a single cell, with intraepithelial extension within the cervical mucosa. By contrast, one uterus contained 2 discontinuous dysplastic foci with different patterns of X-chromosome inactivation, indicating that the 2 lesions developed independently from each other. Our results demonstrate that (i) lesions of CIN3 (severe dysplasia and carcinoma in situ) are composed of a clonal neoplastic population of cells and (ii) most cases of HSIL are unifocal in origin.

Abnormal expansion of peripheral gamma delta T cells in patients with neurologic disorders

The proportions and the variable region usages of peripheral gamma delta T cells were investigated in 205 patients with various neurologic disorders. Flow cytometric analysis was performed with monoclonal antibodies against C delta, V delta 1, V delta 2. V delta 1-J delta 1/J delta 2, and V gamma II (9) epitopes. Further analysis was carried out with reverse transcription-polymerase chain reaction (RT-PCR) using variable region-specific primers. The proportion of gamma delta T cells in 33 patients with cerebral palsy (CP) (mean +/- SD; 11.1 +/- 11.0%) was significantly higher than that in 35 normal controls (5.6 +/- 2.6%) (p < .01). Of 205 patients, persistent gamma delta T cell expansion over 15% was observed in 15 patients (M/F = 13/2). Nine of these 15 were patients with CP. Six of the 9 with CP had neither perinatal nor postnatal events related to the neurologic abnormalities. None of the 9 with CP had active infections or autoimmune disorders that could induce gamma delta T cell expansion. Of the 15, 13 had V gamma II/V delta 2-dominant expansion and 2 showed V delta 1-dominant expansion. Unusual expansions of V delta 4 and V delta 6, which were not usually found in peripheral blood, were detected by RT-PCR in one case with CP and V delta 1-dominant expansion. This study showed subclinical immunologic abnormalities with marked and persistent gamma delta T cell expansion in patients with neurologic disorders, especially CP. These results might indicate the existence of neuroimmunologic disorder(s).

Spectroscopic properties of Nd 3 + and Pr 3 + in gallate glasses with low phonon energies

Absorption and fluorescence spectra of Nd3 +were measured in potassium tantalum gallate, lead bismuth gallate (PBG), fluorozirconate (ZBLAN), and Ge-Ga-S glasses. A Judd -Ofelt analysis was performed to determine the spontaneous emission probability and stimulated emission cross section of the4 F3/2 ?4 I11/2 transition of Nd3 +. Raman spectra were studied to clarify the maximum phonon energies of the glasses. The fluorescence of the1 G4?3 H5 transition of Pr3 + in a dehydrated PBG glass was observed for the first time to our knowledge. The PBG glass has a higher quantum efficiency than that of ZBLAN glass based on the Judd -Ofelt analysis.

Purification, characterization and cloning of a novel variant of the superantigen Yersinia pseudotuberculosis-derived mitogen

The novel superantigen designated as Yersinia pseudotuberculosis-derived mitogen typeB (YPMb) was purified from the cell lysate of Y. pseudotuberculosis O:6 strain (R-104). Proliferative response of human peripheral blood mononuclear cells to the purified YPMb was detectable at a concentration of as low as 1 pg/ml, that is comparable to the previously documented YPM (YPMa). The Vbeta repertoire specificity (3, 9, 13.1 and 13.2) of YPMb was also the same as that of YPMa. A gene (ypmB) encoding YPMb was cloned and its nucleotide sequence was determined. The open reading frame (ORF 453 bp) of the ypmB encodes a protein with 150 amino acid residues, though the precursor protein of YPMa consists of 151 amino acid residues. There is a nucleotide sequence homology of 88.9% between ypmB and ypmA. The low homology in the downstream of the structural gene between ypmB and ypmA and the difference in the GC content in the ORF of ypmB and ypmA from that of the base usage of Y. pseudotuberculosis suggest that the ypm gene originates from another organism. The alignment of the amino acid sequences of mature proteins of YPMb and YPMa revealed that there is 83% homology (108 amino acid residues are identical). Between YPMa and YPMb, the central region is less homologous than the N- and C-terminal regions. Based on the functional similarity of two superantigen molecules, the less homology suggested that the central region is less important for the function of both YPM molecules.

[A clinical study of 1079 patients with laryngeal cancer]

A clinical study was made of 1079 patients with previously untreated laryngeal cancer registered in our department during the 15 years between 1979 and 1993. Their mean age was 64.2 years, ranging from 22 to 91. The male to female ratio was 13:1 and the proportion of non-smokers was 3.2%. These patients consisted of 687 with glottic carcinoma (64%), 373 with supraglottic carcinoma (35%) and 12 with subglottic carcinoma (1%). A sexual difference with regard to the proportion of glottic carcinoma was found; 66% in males and 39% in females. Therefore, the male to female ratios according to the primary sites were 22:1 for the glottis and 8:1 for the supraglottis. According to the TNM classification (UICC 1987), there was a marked difference in the distribution between glottic type and supraglottic type: of the glottic type 439 cases (64%) were stage I, 159 (23%) stage II, 73 (11%) stage III, 16 (2%) stage IV, whereas of the supraglottic type 22 (6%) were stage I, 99 (27%) stage II, 136 (36%) stage III, 116 (31%) stage IV. Our treatment policy for laryngeal cancer has depended not only on the T stage but also on the cancer characteristics including the growing type, anatomical location and extension and depth of invasion. Of the 1079 patients, 1050 were treated radically, 17 palliatively and 12 were not treated. According to the T stage, radical irradiation was chosen for 410 cases (93%) of glottic T1, for 75 cases (45%) of glottic T2 and for 21 cases (81%) of supraglottic T1. Partial laryngectomy was performed in 16 patients (4%) with glottic T1, in 15 patients (10%) with glottic T2 and in 8 patients (6%) with supraglottic T2. Total laryngectomy was performed in almost all patients with T3, T4. The overall 5-year relative survival rate, cumulative crude survival rate and cause-specific survival rate were 84%, 72% and 88%, respectively. The survival rates for the glottic type were significantly higher than those for the supraglottic type (p < 0.0001): the 5-year relative survival rate, cumulative crude survival rate and cause-specific survival rate for the glottic type were 93%, 80%, and 95% whereas for the supraglottic type they were 68%, 58% and 76%, respectively. The 5-year relative survival rates for stage I through stage IV were 96%, 87%, 72% and 53% overall and they were 98%, 91%, 74% and 52% for the glottic type, whereas they were 67%, 83%, 70% and 52% for the supraglottic type, respectively. The results suggested that the better survival rate for glottic T1, which accounted for 64% of all glottic cases, made a great difference in the survival rate between glottic and supraglottic carcinoma.

A metalloproteinase inhibitor prevents lethal acute graft-versus-host disease in mice

Tumor necrosis factor (TNF) and Fas ligand (FasL) have been implicated in the pathogenesis of graft-versus-host disease (GVHD), which is a major complication after allogeneic bone marrow transplantation. We examined here the ameliorating effect of a metalloproteinase inhibitor (KB-R7785) that inhibits TNF-alpha and FasL release in a lethal acute GVHD model in mice. Administration of KB-R7785 into (BALB/c x C57BL/6) F1 that received C57BL/6 spleen cells markedly reduced the mortality and weight loss in association with minimal signs of GVHD pathology in the liver, intestine, and hematopoietic tissues. The ameliorating effect of KB-R7785 was superior to that of anti-TNF-alpha antibody. Our results suggest that KB-R7785 could be a potent therapeutic agent for GVHD.

Mechanisms of central motor reorganization in pediatric hemiplegic patients

Twenty hemiplegic patients were studied with transcranial magnetic stimulation (TMS). Motor evoked potentials (MEPs) of the biceps brachii (BB) and the abductor pollicis brevis muscles (APB) were recorded on both sides simultaneously. TMS was carried out with an 8-shaped coil over different scalp positions in the intact hemisphere. Bilateral MEPs of BB were elicited in patients with later childhood lesions as well as early lesion, but those of APB were only elicited in the latter (up to 2 years). In patients with prenatal or birth lesion on BB and in all patients on APB, cortical maps of MEP amplitude of paretic and non-paretic sides showed similar distributions. There were no remarkable differences in mean latency between both sides, and correlation coefficients of MEP amplitude between both sides were high in these patients. In patients with postnatal lesion on BB, MEP maps of both sides showed different distributions, ipsilateral MEP latencies were delayed and correlation coefficients were low. We suspect that ipsilateral MEPs after early lesion derive from axonal sprouting both in the proximal and the distal muscles. After postnatal lesion, other mechanisms of ipsilateral motor projection take place in the proximal muscles, but not in the distal ones.

Alteration of p16 and p15 genes in common epithelial ovarian tumors

We have examined the roles of 2 putative tumor-suppressor genes, the p16 and p15 inhibitor-of-cyclin-dependent-kinase genes, in the most commonly occurring epithelial tumors of the human ovary. Expression of p16 mRNA, examined by RT-PCR, was significantly reduced in 15 of the 48 tumors. Aberrant expression of p16 protein, detected by immunohistochemistry, occurred in 22 of 60 tumors, more frequently in low-grade tumors, and had significant correlation with low p16 mRNA expression. Hypermethylation of a site within the 5'-CpG island of the p16 gene was significantly associated with loss of p16 mRNA and protein expression. Homozygous gene deletion, evaluated by differential PCR analysis, was found in 2 tumors for the p16 gene and in 1 tumor for the p15 gene among 70 ovarian tumors examined. PCR-SSCP analysis detected point mutations in p16 in 4 tumors and in p15 in 1 tumor. One was a 38-bp deletion, from codons 48 to 60, in a mucinous tumor of low malignant potential; another was a non-sense mutation in codon 60 in a mucinous adenocarcinoma. The remaining 2 mutations were mis-sense mutations, one in codon 58 and the other in codon 60, in 2 endometrioid adenocarcinomas. We conclude that inactivation of p16, by loss of p16 mRNA and protein expression as a consequence of hypermethylation of the 5'-CpG island, rather than by gene deletion or point mutation, may play an important role in the genesis of human ovarian epithelial tumors.

Splenectomy in cancer gastrectomy: recommendation of spleen-preserving for early stages

BACKGROUND

The prognostic significance of splenectomy in cancer gastrectomy was reevaluated, in terms of postoperative survival rate, retrospectively.

MATERIALS AND METHODS

The cumulative survival rates between a splenectomized group (n = 272) and a nonsplenectomized group (n = 192) were compared.

RESULTS

The five-, ten- and fifteen-year survival rates were significantly higher in the nonsplenectomized group in total. When the cancer was classified, according to intraoperative gross findings of the degree of serosal invasion, penetration into adjacent organs and metastases, the five-year cumulative survival rate for Stage I and II patients was significantly higher in the nonsplenectomized group. No significant difference was found between the two groups of Stage II in any of the one- to fifteen-year survival rates. The one-year survival rate for Stage IV patients in the splenectomized group was higher than that in the nonsplenectomized group.

CONCLUSIONS

The splenectomy should be limited to the Stage III or IV patients with some specific findings.

[Second primary cancers occurring in patients with cancers of the mouth and meso-hypo pharynx in Japan]

We evaluated the risk of development of a second primary cancer in 669 patients diagnosed with cancers of the mouth and meso-hypo pharynx at Osaka Medical Center for Cancer and Cardiovascular Diseases. During 1978-93, 70 of the patients developed a second primary cancer, yielding on observed to expected ratio (O/E) of 2.92 [95% confidence interval (CI) = 2.27-3.69]. Significant excess risk was noted for cancers of mouth and pharynx (O/E = 12.01, 95% CI = 3.87-28.04), esophagus (O/E = 25.22, 95% CI = 14.94-39.86), colon (O/E = 3.85, 95% CI = 1.41-8.39), larynx (O/E = 9.93, 95% CI = 2.00-29.02) and lung (O/E = 2.58, 95% CI = 1.24-4.75). The risks of esophageal cancer and colon cancer were significantly elevated after five years had elapsed from the initial cancer diagnoses. The risk of cancers of the oral cavity, pharynx, larynx and esophagus in patients who had a history of current smoking without current daily drinking at the initial diagnosis was elevated past one year after the initial diagnosis (less than 20 cigarettes/ day; O/E = 12.50, 95% CI = 0.16-69.55, 20 cigarettes or more; O/E = 10.00, 95% CI = 1.12-36.10). The risk of cancers of the oral cavity, pharynx, larynx and esophagus in patients who had a history of current smoking with current daily drinking at the initial diagnosis was around two times higher than those who had a history of current smoking without current daily drinking (less than 20 cigarettes/day; O/E = 20.00, 95% CI = 2.25-72.21, 20 cigarettes or more; O/ E = 19.51, 95% CI = 8.40-38.45).

Physical mapping of rice chromosomes 4 and 7 using YAC clones

Physical maps of rice chromosomes 4 and 7 were constructed by landing yeast artificial chromosomes (YACs) along our high-density molecular linkage map. Using 114 DNA markers, 258 individual YACs were located on chromosome 4. Sixty-two out of 258 YACs carried two or more DNA marker positions and formed 16 contigs which covered a total length of 17.1 cM. The other YACs were arranged to 23 positions. On chromosome 7, 203 individual YACs were landed on 109 DNA markers. Sixty-four out of 203 YACs formed 15 contigs which covered a total length of 21.8 cM and 139 YACs were localized to 26 positions. Chromosomes 4 and 7 were covered with minimum tiling paths of 45 and 48 YACs, respectively. Taking the average size of YAC insert DNA to be 350 kb and the entire genome size to be 430 Mb, about 16-18 Mb of each chromosome or an estimated 50% of their total lengths have been covered with YACs. Physical maps of these 2 chromosomes should be of great help in identifying useful trait genes and unraveling genetic and biological characteristics in rice.

Studies on selectin blockers. 4. Structure-function relationships of sulfated sialyl Lewis X hexasaccharide ceramides toward E-, P-, and L-selectin binding

In order to clarify the real ligand structure of L-selectin proposed by Rosen et al., we first synthesized 6-sulfated sLe(x) hexasaccharide ceramide 1, 6'-sulfated sLe(x) hexasaccharide ceramide 2, and 6,6'-disulfated sLe(x) hexasaccharide ceramide 3 and examined their binding avidities for L-selectin. As a result, we found that the 6'-sulfated sLe(x) hexasaccharide ceramides 1-3 have similar binding avidities to L-selectin and their binding to L-selectin appeared somewhat stronger than that of sLe(x). For P-selectin, the sulfated sLe(x) derivatives 1-3 showed a similar avidity to sLe(x). On the other hand, 6-sulfated sLe(x) 2 was recognized to E-selectin and the binding avidity was apparently weak as compared to that of sLe(x) hexasaccharide ceramide. Surprisingly, 6'-sulfated and 6,6'-disulfated sLe(x)s 1 and 3 did not bind to E-selectin at all. We constructed the E-selectin-sLe(x) complex model and investigated the binding mode. Namely, the galactose 6'-position was directed toward the negatively charged residues, Glu80 and Asp100. Our results with E-selectin indicate that the replacement of 6'-OH position from anionic charged group to cationic charged one, e.g., amino groups, could have a marked affect on E-selectin recognition. These results could provide useful information for the drug design of selectin blockers.

Nucleotide sequence of a gene encoding the novel Yersinia enterocolitica heat-stable enterotoxin that includes a pro-region-like sequence in its mature toxin molecule

A novel ST (Y-STc) produced by a pathogenic strain of Yersinia enterocolitica was recently purified and the mature toxin was found to include the pro-region-like sequence (Yoshino et al., FEBS Lett 362: 319-322, 1995). In the present study, we report the nucleotide sequence of the ystC gene. We also present the amino acid sequence of a ystC gene product secreted by a recombinant strain of Escherichia coli. From the nucleotide sequence of ystC gene, the Y-STc precursor protein was deduced to consist of 72 amino acid residues and to be comprised of two regions (pre- and mature toxin regions), while the known ST precursor proteins are comprised of three regions (pre-, pro-, and mature toxin regions). Therefore, we concluded that a long polypeptide corresponding to a pro-toxin of other Sts is secreted as the Y-STc mature toxin. This implies that the proteolytic processing of a pro-form appearing in the periplasm is not essential for the secretion of Yersinia-ST to the extracellular through the outer membrane. The recombinant Y-STc released by E. coli was found to be shorter and composed of C-terminal 24 amino acid residues of the native Y-STc. On the basis of these results, we propose that the cleavage site between the pro- and mature toxin regions of ST depends on both the amino acid sequence of the pro-toxin and on the bacterial protease system responsible for the maturation.

Correlation of goblet cell density and mucosal epithelial membrane mucin expression with rose bengal staining in patients with ocular irritation

PURPOSE

This study was designed to compare goblet cell densities and mucosal epithelial membrane mucin (MEM) expression in impression cytology specimens obtained from control subjects and patients with one of the following clinically defined diseases: aqueous tear deficiency (ATD) associated with Sjögren syndrome, ATD not associated with Sjögren syndrome, inflammatory Meibomian gland disease associated with rosacea, and Meibomian gland atrophy. These data were correlated with ocular surface rose Bengal staining scores, Schirmer scores, and HLA-DR antigen staining of conjunctival epithelial cells.

METHODS

Goblet cell density and MEM expression were studied by impression imprints with immunohistochemical staining using an anti-mucosal epithelial membrane mucin antibody in the temporal and inferior bulbar and inferior tarsal conjunctiva of study subjects.

RESULTS

Goblet cell density adjacent to the temporal limbus was significantly reduced at 3 mm posterior to the temporal limbus in both aqueous tear deficiency groups compared with the other groups and in patients with Sjögren syndrome compared with all other groups. In the inferior tarsus, goblet cell density was significantly reduced in patients with non-Sjögren syndrome ATD as compared with all other groups, except those with inflammatory Meibomian gland disease. Mucosal epithelial membrane mucin expression in the bulbar and tarsal conjunctiva was absent in a greater percentage of patients with Sjögren syndrome compared with all other groups. Total ocular surface rose Bengal staining scores were significantly higher in patients with Sjögren syndrome as compared with all other groups and in patients with non-Sjögren syndrome ATD as compared with control groups. Rose Bengal staining scores and Schirmer I test results (without anesthesia) were inversely correlated with bulbar, but not tarsal, conjunctival goblet cell densities, and with the absence of bulbar conjunctival MEM expression.

CONCLUSIONS

These results suggest that reduced goblet cell density and mucosal epithelial cell mucin expression could explain increased rose Bengal staining in patients with aqueous tear deficiency. In addition, MEM may be regarded as a marker for normal differentiation of ocular surface epithelia, with its absence signifying the development of squamous metaplasia.

Management for stage II glottic carcinoma: radiation therapy or surgery

AIM

To analyze the results of stage II glottic carcinoma treated with radiotherapy or surgery.

PATIENTS AND METHOD

One hundred thirty-four patients with squamous cell carcinoma of the T2N0M0 glottic carcinoma treated at the Osaka Medical Center for Cancer and Cardiovascular Diseases from 1979 through 1991 were reviewed. The 5-year disease-free survival and laryngeal preservation rate and prognostic factors were examined. Treatment was radiation therapy with salvage surgery for failure or surgery alone.

RESULTS

The 5-year disease-specific survival rate for the radiotherapy group was 100% and for the surgery group, 93% (p = 0.055). In the surgery group 5-year disease-specific survival rate for the subgroup of cord mobility was 94% and that of impaired cord mobility, 89% (p = 0.5354). Concerning laryngeal preservation the radiotherapy group showed better preservation rate than the surgery group in the subgroup of cord mobility, i.e., 41/51 (80%) versus 6/55 (11%) (p < 0.001) although significant difference was not observed in the lesion with impaired cord mobility, 2/5 versus 4/22 (p = 0.171).

CONCLUSION

We recommend radiation therapy for stage II glottic carcinoma with normal cord mobility, although further study is needed to improve the preservation rate of the larynx with keeping the disease-specific survival for the lesion with impaired cord mobility.

Synthesis and structure-activity relationships of novel phenylcyanoguanidine derivatives as potassium channel openers

3,5-Di-substituted phenylcyanoguanidine derivatives with halogen, cyano and/or nitro groups at the 3- and 5-positions of the benzene ring exhibited very strong smooth muscle relaxation activity in vitro, as compared to pinacidil. Among them, N-(3-chloro-5-cyanophenyl)-N'-cyano-N" -tert-pentylguanidine (5s) showed 27-fold more potent activity than pinacidil, and exhibited a stronger and more lasting antihypertensive effect than pinacidil by oral administration to spontaneously hypertensive rats. We propose a new pharmacophore model in which the essential factors for binding to the potassium channel are an NH and a bulky alkyl group.

Vaginal arteriovenous malformation: MR imaging

Vaginal arteriovenous malformations (AVMs), although rare, can lead to life-threatening complications. We report the first case of a vaginal AVM whose diagnosis and follow-up were performed by magnetic resonance imaging (MRI). MRI findings of the AVM are the blood flow-related features within the tumor, such as the phase-shift artifact, paradoxical enhancement, and flow voids.

Cholinergic stimulation of lactoferrin and epidermal growth factor secretion by the human lacrimal gland

The human lacrimal gland produces tear proteins, such as lactoferrin and epidermal growth factor (EGF), that have presumed biologic activity on the ocular surface. We hypothesized that secretion of these tear proteins by the lacrimal gland is neurally mediated. To test this hypothesis, we evaluated the secretion of lactoferrin and EGF from the human lacrimal gland (LG) after cholinergic stimulation. Human LG biopsies from two donors were sliced into sections weighing approximately 100 mg and were serially placed in wells containing Dulbecco's modified Eagle's medium (DMEM/F12; with or without atropine), followed by media alone, media containing carbamylcholine chloride (carbachol), and then media alone, each for 10 min. Supernatants were then assayed for lactoferrin and EGF by antibody sandwich enzyme-linked immunosorbent assay (ELISA). Both sets of LG explants showed statistically significant increases in supernatant concentrations of lactoferrin and EGF 10 min after cholinergic stimulation. These returned to prestimulation concentrations by 20 min. Atropine-pretreated explants showed no significant change in supernatant concentrations of these proteins after carbachol stimulation. The results of these studies indicate that cholinergic stimulation of the human LG results in increased secretion of the tear proteins lactoferrin and EGF. This suggests that the LG can respond to the ocular surface environment by increasing secretion of biologically active tear constituents through neural stimulation.