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Charge interactions play a critical role in the activation of the innate immune system by damage- and pathogen-associated molecular pattern receptors. The ability of these receptors to recognize a wide spectrum of ligands through a common mechanism is critical in host defense. In this article, we argue that platelet glycoprotein receptors that signal through conserved tyrosine-based motifs function as pattern recognition receptors (PRRs) for charged endogenous and exogenous ligands, including sulfated polysaccharides, charged proteins and nanoparticles. This is exemplified by GPVI, CLEC-2 and PEAR1 which are activated by a wide spectrum of endogenous and exogenous ligands, including diesel exhaust particles, sulfated polysaccharides and charged surfaces. We propose that this mechanism has evolved to drive rapid activation of platelets at sites of injury, but that under some conditions it can drive occlusive thrombosis, for example, when blood comes into contact with infectious agents or toxins. In this Opinion Article, we discuss mechanisms behind charge-mediated platelet activation and opportunities for designing nanoparticles and related agents such as dendrimers as novel antithrombotics.

Objective— Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is a collagen receptor that belongs to the inhibitory immunoreceptor tyrosine-based inhibition motif–containing receptor family. It is an inhibitor of signaling via the immunoreceptor tyrosine-based activation motif–containing collagen receptor complex, glycoprotein VI-FcRγ-chain. It is expressed on hematopoietic cells, including immature megakaryocytes, but is not detectable on platelets. Although the inhibitory function of LAIR-1 has been described in leukocytes, its physiological role in megakaryocytes and in particular in platelet formation has not been explored. In this study, we investigate the role of LAIR-1 in megakaryocyte development and platelet production by generating LAIR-1–deficient mice. Approach and Results— Mice lacking LAIR-1 exhibit a significant increase in platelet counts, a prolonged platelet half-life in vivo, and increased proplatelet formation in vitro. Interestingly, platelets from LAIR-1–deficient mice exhibit an enhanced reactivity to collagen and the glycoprotein VI–specific agonist collagen-related peptide despite not expressing LAIR-1, and mice showed enhanced thrombus formation in the carotid artery after ferric chloride injury. Targeted deletion of LAIR-1 in mice results in an increase in signaling downstream of the glycoprotein VI–FcRγ-chain and integrin αIIbβ3 in megakaryocytes because of enhanced Src family kinase activity. Conclusions— Findings from this study demonstrate that ablation of LAIR-1 in megakaryocytes leads to increased Src family kinase activity and downstream signaling in response to collagen that is transmitted to platelets, rendering them hyper-reactive specifically to agonists that signal through Syk tyrosine kinases, but not to G-protein–coupled receptors.

Key Points Platelet activation in vitro results in a more rapid and greater upregulation of TLT-1 surface expression compared with P-selectin. TLT-1 is more rapidly translocated to the surface of activated platelets than P-selectin during thrombus formation in vivo.

Osteosarcoma (OS) is a primary malignant tumour of bone occurring predominantly in children and young adults. Despite chemotherapy, relapse is common and mortality remains high. Non-transformed osteoblasts are highly sensitive to glucocorticoids, which reduce proliferation and induce apoptosis. Previously, we observed that OS cells, but not normal osteoblasts, express 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). This enzyme inactivates cortisol (active) to cortisone (inactive) and expression of 11β-HSD2 renders OS cells resistant to glucocorticoids. By contrast, the related enzyme 11β-HSD1 converts cortisone to cortisol and reduces OS cell proliferation in vitro. Some synthetic glucocorticoids (e.g. dehydrodexamethasone (DHD), inactive counterpart of dexamethasone (DEX)) have been reported to be activated by 11β-HSD2. We therefore investigated expression and enzymatic activity of 11β-HSD isozymes in human OS tissue, determined whether 11β-HSD expression has prognostic value in the response to therapy, and evaluated the potential use of synthetic glucocorticoids to selectively target OS cells. OS samples expressed both 11β-HSD1 and 11β-HSD2. 11β-HSD1 expression in pretreatment biopsy specimens positively correlated with primary tumour size. Expression and activity of 11β-HSD1 in post-treatment biopsies were unrelated to the degree of tumour necrosis following chemotherapy. However, high 11β-HSD2 expression in post-treatment biopsies correlated with a poor response to therapy. OS cells that expressed 11β-HSD2 inactivated endogenous glucocorticoids; but these cells were also able to generate DEX from DHD. These results suggest that OS treatment response is related to 11β-HSD2 enzyme expression. Furthermore, OS cells expressing this enzyme could be targeted by treatment with synthetic glucocorticoids that are selectively reactivated by the enzyme.

Context: Isolated 17,20 lyase deficiency is commonly defined by apparently normal 17α-hydroxylase activity but severely reduced 17,20 lyase activity of the bifunctional enzyme cytochrome P450 (CYP) enzyme 17A1 (CYP17A1), resulting in sex steroid deficiency but normal glucocorticoid and mineralocorticoid reserve. Cytochrome b5 (CYB5A) is thought to selectively enhance 17,20 lyase activity by facilitating the allosteric interaction of CYP17A1 with its electron donor P450 oxidoreductase (POR). Objective: We investigated a large consanguineous family including three siblings with 46,XY disorder of sex development (DSD) presenting with isolated 17,20 lyase deficiency. Design: We investigated the clinical and biochemical phenotype, conducted genetic analyses, and functionally characterized the identified CYB5A mutation in cell-based CYP17A1 coexpression assays. Results: All three siblings presented with 46,XY DSD, sex steroid deficiency, normal mineralocorticoids and glucocorticoids, and a urine steroid metabolome suggestive of isolated 17,20 lyase deficiency. CYP17A1 and POR sequences were normal, but we detected a homozygous CYB5A missense mutation (g.28,400A→T; p.H44L). Functional in vitro analysis revealed normal CYP17A1 17α-hydroxylase activity but severely impaired 17,20 lyase activity. In silico analysis suggested the disruption of CYB5A heme binding by p.H44L. Conclusion: We have identified the first human CYB5A missense mutation as the cause of isolated 17,20 lyase deficiency in three individuals with 46,XY DSD. Detailed review of previously reported cases with apparently isolated 17,20 lyase deficiency due to mutant CYP17A1 and POR reveals impaired 17α-hydroxylase activity as assessed by steroid metabolome analysis and short cosyntropin testing. This suggests that truly isolated 17,20 lyase deficiency is observed only in individuals with inactivating CYB5A mutations.

Background This phase II study evaluates the tolerability and efficacy of concurrent hyperfractionated radiation therapy (HFX-RT) and high-dose intra-arterial (IA) cisplatin in patients with locally advanced squamous cell carcinoma of the head and neck (SCCHN). Methods Between December 1995 and November 1997, 20 patients with locally advanced T4/T3 SCCHN were treated with HFX-RT (76.8–79.2 Gy at 1.2 Gy bid over 6–7 weeks) and high-dose IA cisplatin (150 mg/m2 given at the start of RT boost treatment [start of week 6]). Seventeen patients (85%) had T4 disease, and 14 (70%) had N2/ N3 disease. Results Grade 3-5 acute toxicity was limited to one grade 4 (5%) and 14 grade 3 (70%) mucosal events. No grade 3/4 hematologic toxicity was observed. Median weight loss during therapy was 9% (range, 2%–16%). Eighteen patients had complete response (90%) at the primary site; 14 were confirmed pathologically. Among 17 patients with positive neck disease, 16 (94%) achieved complete response in the neck, including 12 of 13 patients with N2/N3 disease who underwent planned neck dissection. Active follow-up ranges from 12 to 32 months (median, 20 months) with 11 patients alive without disease, 5 dead of disease, and 4 dead of intercurrent disease. Eighteen patients (90%) remained disease free at the primary site, and the locoregional control rate is 80%. Conclusions High-dose IA cisplatin and concurrent HFX-RT as used in this study is feasible and warrants further investigation. The high complete response rate and low grade 4 toxicity in this highly unfavorable subset of patients appears better than previously reported chemoradiation regimens for more favorable patients. © 2000 John Wiley & Sons, Inc. Head Neck 22: 543–549, 2000.

Background There is little literature comparatively evaluating the results of postoperative radiation therapy (RT) for patients with squamous cell carcinoma (SCC) of the head and neck treated for primary versus recurrent disease. Methods Between 1981 and 1993, 174 patients with SCC of the head and neck, 143 with primary and 31 with recurrent disease, were treated with standard postoperative RT. Results Patients treated for primary disease had 5-year local-regional control (LRC) and disease-specific survival (DSS) rates of 69% and 54%, respectively, as compared with 46% and 32%, respectively, for patients treated for recurrent disease (P = 0.03 and 0.04, respectively). On multivariate analysis, only tumor type (primary vs recurrent) significantly influenced LRC (P = 0.003) and only primary tumor site (oral cavity vs nonoral cavity) significantly influenced DSS (P = 0.04). Among the patients treated for recurrent disease, site of recurrence (undissected vs dissected tissue) significantly influenced both LRC and DSS (P = 0.008 and 0.001, respectively). Conclusions Patients with recurrent SCC of the head and neck do poorly as compared with those with primary disease when treated with standard postoperative RT, particularly when the recurrence is within previously dissected tissue. This patient group should be targeted for alternative treatment strategies. © 1999 John Wiley & Sons, Inc. Head Neck 21: 554–559, 1999.

Purpose Postoperative radiation therapy (RT) following surgical resection is often the recommended treatment for recurrent squamous cell carcinoma (SCC) of the head and neck. Despite common use, there are few published series evaluating such a management approach. Methods and materials We evaluated the efficacy of postoperative RT in 31 patients with recurrent SCC of the head and neck treated between 1981 and 1993. None of the patients had prior RT. All had complete resection of recurrent gross disease and no distant metastases. Maximum postoperative RT doses ranged from 59.4-70 Gy (median = 66 Gy). Results The 5-year disease-specific survival (DSS) and local control (LC) rate for all patients were 32 and 46%, respectively. Several prognostic factors were analyzed including site and stage of original primary tumor, disease-free interval, site of recurrence, status of surgical margins, and dose. Only site of recurrence significantly influenced both DSS and LC. Patients whose recurrence was limited to previously undissected tissue had 5-year DSS and local control rates of 60 and 74%, respectively, as compared to 19 and 29%, respectively, for patients whose recurrence was within previously dissected tissue (p = 0.05). Conclusions Patients with recurrent SCC of the head and neck treated with standard postoperative RT following surgical resection do relatively well if the recurrence is within previously undissected tissue (i.e., nodal only); however, patients whose recurrence is within previously dissected tissue do poorly. Every effort to prevent locoregional disease recurrence at the time of primary therapy should be emphasized.

The management of residual, recurrent, or small skull base meningiomas is controversial. Stereotactic radiosurgery has emerged as an alternative treatment. We report our experience from September 1991 to August 1994 of treatment of 20 such patients [18 females -age 19-82 years, followed for 6-36 months (mean 15.5 months)] with the Leksell Gamma Knife. Nine patients were treated either with recurrent (2 patients-2 operations each) or residual tumor. Twelve patients had skull base, 3 optic nerve, 3 parasagittal, and 1 residual torcular tumor. Mean volume/diameter was 9.172 mm3/25 mm.

Background The recreational abuse of anabolic steroids is an emerging global health concern and may disrupt cardiac electrophysiology. Every fifth man joining a gym in the UK uses anabolic steroids for performance enhancement. Based on molecular signaling analyses and considering the volume-loading effects of testosterone, individuals with vulnerable desmosomal (cell-cell contact) proteins may be at increased risk of anabolic steroid induced cardiac electrical remodeling. We therefore studied the impact of chronic anabolic steroid exposure on left atrial (LA) electrophysiology in wildtype (WT) and plakoglobin (Plako; or gamma-catenin, a key desmosomal protein) deficient mice using dihydro-testosterone (DHT-a stable derivative of testosterone). Methods Young adult WT and Plako +/- male mice, bred on 129/sv background were fitted with subcutaneous osmotic mini-pumps containing either DHT (62.5mg/ml) in ethanol, or ethanol alone (Placebo), for 6 weeks. Following treatment, we examined transmembrane action potentials, and generated high spatial resolution activation maps in the Di-4-Anepps loaded LA using the Hamamatsu ORCA flash 4. Significance was taken as P Results DHT minipump exposure lead to supraphysiological DHT plasma levels and increased the ventricular mass:tibial length ratio of both genotypes (WT Placebo 79 ± 2 Plako +/- Placebo 78 ± 2 WT DHT 86 ± 3 Plako +/- DHT 92 ± 3 mg/cm, P +/- LA mass:tibial length ratio (WT Placebo 2.4 ± 0.1 Plako +/- Placebo 2.3 ± 0.1 WT DHT 2.6 ± 0.2 Plako +/- DHT 3.2 ± 0.2mg/cm, P +/- Placebo 0.14 ± 0.006 WT DHT 0.16 ± 0.004, Plako +/- DHT 0.24 ± 0.04 mm 2 , P DHT reduced action potential amplitude in Plako +/- LA, but not WT LA (WT Placebo 82 ± 2 Plako+/- Placebo 80 ± 2 WT DHT 80 ± 2 Plako+/- DHT 71 ± 2mV, P +/- DHT 82 ± 5 V/s, P +/- LA following DHT exposure (WT Placebo 40 ± 0.3 Plako +/- Placebo 40 ± 0.9 WT DHT 37 ± 1.3 Plako +/- DHT 36 ± 1.4 cm/s, P Conclusion Reduced cardiac plakoglobin expression increased susceptibility to steroid-induced left atrial hypertrophy, reduced action potential amplitude and lead to significant conduction slowing. These differences are likely to provide an enhanced substrate for atrial arrhythmogenesis. Our results suggest a potentially important interaction between reduced mechanical cell-cell contacts and anabolic steroid use.

Cu(II) binuclear binary and mixed-ligand complexes involving histidine [A] as binucleating ligand and amino acids (L = glycine, α-alanine, phenylalanine, tyrosine, tryptophan) or bipy [L] have been investigated by potentiometry, UV-VIS spectrophotometry, and cyclic voltametry in aqueous medium at 30°C and I = 0.2 M(NaClO 4 ). Experimental data have been obtained for the following species: [CuAH], [CuA], [CuACu], [LCuAH], [LCuA], [LCuACu], and [LCuACuL]. The formation of new binuclear species has been confirmed by UV-VIS spectral studies and CV studies in aqueous solution. The stability of the complexes has been explained on the basis of intramolecular interligand interactions between the side groups over the ligands.

Homo binuclear binary and mixed-ligand complexes of Cu(II) with L-dopa [A] and amino acids [L] (glycine, α-alanine, phenylalanine, tyrosine, tryptophan) or Bipy [L] have been investigated by potentiometry, UV-VIS spectrophotometry and cyclic voltametry in aqueous medium at T = 30°C and I = 0.2 M (NaClO4). Experimental data have been obtained for the following species: [CuAH2], [CuACu], [CuAH2L], [LCuACu], and [LCuACuL]. The formation of binuclear species has been confirmed by UV-VIS spectral studies and C.V. studies in solutions. The stability of the complexes has been explained on the basis of intramolecular interligand interactions between the side groups over the ligands.

Stability constants of homobinuclear binary Cu(II) complexes of the dinucleating ligands, having equivalent coordination sites, 5,5′-methylene-bis-salicylaldehyde (H2A1), 5,5′-methylene-bis-(3-bromosalicylaldehyde) (H2A2), and 5,5′-methylene-bis-(3-nitrosalicylaldehyde) (H2A3), and mixed ligand Cu(II) complexes with one of the above ligands and bipyridyl (L1) or 1,10-phenanthroline (L2) as second ligand, have been determined potentiometrically in water:dioxane medium (50:50 and 30:70,v/v using a computer programme. The values of [Formula: see text] and [Formula: see text] have been compared within the series of complexes having different H2A and L. Probable explanations for the stability order have been extended. The complexes (Cu2AL2)(ClO4)2 have been isolated and characterized by elemental analysis, electronic and ESR spectral, and magnetic studies.

Type II diabetes has a substantial genetic component, but the mode of inheritance and the molecular basis of this inheritance are uncertain. This study documents the familial distribution of the disease in the parents and siblings of a consecutive series of type II diabetic subjects. We studied 66 first-degree relatives of 20 white subjects with type II diabetes and both parents alive. They were tested with a continuous infusion of glucose (5 mg · kg IBW−1 · min−1) (n = 49) or FPG and hemoglobin A1c (n = 17). Seven probands had neither parent affected with diabetes or IGT, 10 had one parent affected (6 with diabetes and 4 with IGT), and 3 had both parents affected. The probands with affected and those with unaffected parents were phenotypically similar. These findings indicate that a sizable subgroup of type II diabetic subjects may have neither parent affected with a demonstrable abnormality of glucose tolerance. The assumption of autosomal dominance with complete penetrance is not supported, although it remains possible that a dominant gene of low penetrance may play a role in some pedigrees. Polygenic inheritance would appear likely, and genetic heterogeneity may occur. The inheritance of diabetic traits from phenotypically normal parents needs to be considered in the analysis of genetic linkage with type II diabetes.

The case report by Burnet and Blake (1989), “Sustained complete remission of Stage IV carcinoma of the cervix with cisplatinum, methotrexate and bleomycin chemotherapy”, was of great interest. We have found californium-252 (Cf-252) neutron brachytherapy (Cf-NT) to be highly effective for local control of bulky T4 squamous cell carcinoma of the tonsiloropharynx (Maruyama, 1984). Hence, we tested Cf-NT with adjuvant cisplatin-based chemotherapy for treatment of a case of advanced and metastatic oral cavity squamous cell cancer. Cisplatin plus 5-fluorouracil is an effective combination (Decker et al, 1983; Campbell et al, 1987; Toohill et al, 1987; Taylor et al, 1989), which we used.

Objective/Hypothesis: To evaluate incidence, site of occurrence and outcome of second malignant neoplasia (SMN) in patients with T1 glottic cancer treated with radiation. Study Design: Retrospective. Methods: Between February 1964 and May 1993, 158 patients with T1 squamous carcinoma of the larynx were treated with definitive radiation. Incidence, site (aerodigestive tract or not) and outcome of SMN were analyzed. Median follow-up was 63 months (range, 12–245 mo). Results: Thirty-four patients developed SMN, for an overall incidence of 22%. Twenty-four (67%) SMNs occurred in an aero-upper-digestive-tract site compared with nine (25%) occurring in a non-aero-upper-digestive tract site. The incidence of SMN observed was higher than would be expected for the general population at risk. The observed-to-expected ratios (OER) for all SMN, aero-upper-digestive SMN and non-aero-upper-digestive SMNs were 1.73, 5.53, and 0.62, respectively. Overall 5- and 10-year survivals were 76% and 57%, respectively, for those who did not develop SMN, as compared with 68% and 26%, for those who developed SMN (P = .003). Overall, 13 patients (8.2%) have died from laryngeal cancer, while 23 (15%) died from SMN (P = .001). Conclusion: This study confirms a higher incidence of SMN in T1 glottic cancer patients, compared with the general population. The majority of cases occur in aero-upper-digestive sites. These patients are more likely to die from their SMN than from glottic cancer. Patients with T1 squamous cell carcinoma of the glottic larynx represent a group of head and neck cancer patients who should be targeted in studies evaluating the potential benefits of chemoprevention, and aggressively counseled for social and/or behavioral modifications.

One hundred eighty-three patients with floor of the mouth cancer, of whom 162 were evaluable, were treated between 1962 and 1987. Most patients (139) received treatment with curative intent. Forty-seven received surgery only; 45 received radiotherapy (RT) only; 23 received preoperative RT and surgery; 24 received surgery and postoperative RT. A subset of 30 patients received brachytherapy and external beam RT. Overall survival rates were: surgery only, 90%/68% (2 years/5 years); RT only, 65%/45%; preoperative RT, 65%/43%; and postoperative RT, 78%/41%. Patients receiving surgery generally had lower stage disease and good performance status; RT patients generally had higher stage disease—(64% had stages III and IV disease). Patients receiving RT also had over twice the incidence of deaths from intercurrent disease. These were the contributing factors to the lower survival rate of the patients receiving RT. Disease-free survivals were similar between the groups. In contrast, locoregional control was better for patients receiving RT, particularly in the postoperative RT and brachytherapy groups. Locoregional control rates were: surgery only, 59%/52% (2 years/5 years); RT only, 78%/69%; preoperative RT, 75%/58%; postoperative RT, 80%/74%; and brachytherapy, 96%/89%. This advantage in locoregional control was marked in patients with advanced local disease and was evident at 2 years and beyond. Treatment approaches evolved during the study period toward the use of surgery only in lower stages and combined with RT (usually postoperative) in higher stages. (Arch Otolaryngol Head Neck Surg. 1994;120:260-263)

We have investigated the use of a nested polymerase chain reaction assay for the detection of a fetal-specific Y-chromosomal sequence (DYS14) from DNA extracted from unsorted maternal peripheral blood. Serial dilutions of male DNA into female cord blood DNA indicated that the assay could detect an equivalent of a single male cell in 300,000 female cells. The assay exhibited absolute specificity for male DNA with no amplification from a DNA panel obtained from 10 female cord blood samples. When used on DNA extracted from unsorted peripheral blood from a series of pregnant women, the predictive values of a positive test for a male fetus were 86%, 67% and 87% in the first, second and third trimesters, respectively. We have also demonstrated that retesting the samples allows the detection of a proportion of male-bearing pregnancies with a high degree of accuracy, in that all 15 women who gave positive signals in two consecutive amplifications had male fetuses. We have also applied the test at 8 weeks postpartum to eight women who had previously delivered male babies; no Y-specific signal could be detected in any of them, suggesting that most women have cleared their circulation of fetal cells by 8 weeks after parturition.

To facilitate its use in the clinic, Barendsen's formulation of the Linear-Quadratic (LQ) model is modified by expressing isoeffect doses in terms of the "Standard Effective Dose," Ds, the isoeffective dose for the "standard" fractionation schedule of 2 Gy fractions given once per day, 5 days per week. For any arbitrary fractionation schedule, where total dose D is given in N fractions of size d in a total time T, the corresponding "Standard Effective Dose," Ds, will be proportional to the total dose D and the proportionality constant will be called the "Standard Relative Effectiveness," SRE, to distinguish it from Barendsen's "Relative Effectiveness," RE. Thus, Ds = SRE.D. The constant SRE depends on the parameters of the fractionation schedule, and on the tumor or normal tissue being irradiated. For the "simple" LQ model with no time dependence, which is applicable to late reacting tissue, SRE = [(d + delta)/(2 + delta)], where d is the fraction size and delta = alpha/beta is the alpha/beta ratio for the tissue of interest, with both d and delta expressed in units of Gy. Application of this method to the Linear Quadratic model with a time dependence, the "LQ + time" model, and to low dose rate brachytherapy will be discussed. To clarify the method of calculation, and to demonstrate its simplicity, examples from the clinical literature will be used.

Purpose/Objective: Postoperative irradiation (XRT) following surgical resection is the often recommended treatment for resected advanced primary and resected recurrent squamous cell carcinoma (SCC) of the head and neck. Despite common use, there is little literature comparatively evaluating the results of such a management approach between those patients irradiated postoperatively for primary versus recurrent disease. This study evaluates the efficacy of postoperative XRT in patients with recurreni SCC of the head and neck and compares their outcome to patients with primary SCC of the head and neck treated with postoperative XRT over the same time period. Materials & Methods: Between 1981 and 1993, 174 patients with SCC of the head and neck, 143 with primary and 31 with recurrent disease, were treated with standard postoperative XRT. All had complete resection of gross disease, no distant metastasis, or prior XRT. All patients were treated with non-split course XRT at 1.8-2.0 Gy per fraction. Median total postoperative XRT dose was 66 Gy (range = 50. 72Gy). Median follow-up is 68 months (range = 22-159 months). Several potential prognostic factors for disease-specific survival (DSS) and local-regional control (LRC) were analyzed and included tumor type (primary vs. recurren& site and stage of original tumor, status of surgical margins, disease-free interval, site and extent of recurrence, and dose. Results: For all 174 patients, the .5-year DSS and LRC rates were 50% and 65%, respectively. On univariate analysis, both tumor type and original tumor site significantly influenced DSS and LRC. Patients treated forprimary disease had 5.year DSS and LRC rates of 54% and 69%, respectively, as compared to 32% and 46%, respectively for patients treated for recurrem disease (P=O.O4 and 0.03, respectively). Patients with a non-oral cavity original tumor had 5-year DSS and LRC rates of 55% and 73%, respectively, as compared to 39% and 44%, respectively, for patients with an oral cavity original tumor ( P=O.O5 and 0.002, respectively). On multivariate analysis, only primary tumor site significantly influenced DSS (P=O.O4) and only tumor type significantly influenced LRC (P=O.O03). Among the 143 patients treated for primary disease, no factors analyzed significantly influenced DSS, while on multivariate analysis, only surgical margin status significantly influenced LRC. Patients treated for primary disease with negative margins had a 5-year LRC rate of 78% as compared to 61% for those with positive /close margins (P&03). Among the 3 1 patients treated for recurrent disease. the factor which significantly influenced both DSS and LRC on multivariate analysis was site of recurrence. Patients whose recurrence was limited to previously undissected tissue had 5-year DSS and LRC rates of 60% and 74%, respectively, as compared to 19% and 29%, respectively, for patients whose recurrence was within previously dissected tissue (P=O.OOl and 0.008, respectively). Conclusion: Patients with recurrent SCC of the head and neck do poorly when treated with standard postoperative XRT following surgical resection, especially if the recurrence is within previously dissected tissue, as compared to patients treated forprimaiy disease. This may be related to the negative effects of hypoxia on the efficacy of XRT or an intrinsically resistant tumor clone. This patient group should be targeted for alternative local treatment strategies, including dose escalation and/or altered fractionation.

Background Hydrogen sulphide is a gas signalling molecule which is produced endogenously from L-cysteine via the enzymes cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). The possible role of hydrogen sulphide in reproduction has not yet been fully investigated. It has been previously demonstrated that hydrogen sulphide relaxes uterine smooth muscle in vitro. The aim of the present study was to investigate the endogenous production of hydrogen sulphide in rat and human intrauterine tissues in vitro. Methods The production of hydrogen sulphide in rat and human intrauterine tissues was measured in vitro using a standard technique. The expression of CBS and CSE was also investigated in rat and human intrauterine tissues via Western blotting. Furthermore, the effects of nitric oxide (NO) and low oxygen conditions on the production rates of hydrogen sulphide were investigated. Results The order of hydrogen sulphide production rates (mean +/- SD, n = 4) for rat tissues were: liver (777 +/- 163 nM/min/g) > uterus (168 +/- 100 nM/min/g) > fetal membranes (22.3 +/- 15.0 nM/min/g) > placenta (11.1 +/- 4.7 nM/min/g), compared to human placenta (200 +/- 102 nM/min/g). NO significantly increased hydrogen sulphide production in rat fetal membranes (P < 0.05). Under low oxygen conditions the production of hydrogen sulphide was significantly elevated in human placenta, rat liver, uterus and fetal membranes (P < 0.05). Western blotting (n = 4) detected the expression of CBS and CSE in all rat intrauterine tissues, and in human placenta, myometrium, amnion and chorion. Conclusion Rat and human intrauterine tissues produce hydrogen sulphide in vitro possibly via CBS and CSE enzymes. NO increased the production of hydrogen sulphide in rat fetal membranes. The augmentation of hydrogen sulphide production in human intrauterine tissues in a low oxygen environment could have a role in pathophysiology of pregnancy.