Geckos: adaptive significance and energetics of tail autotomy.

Coleonyx variegatus is adapted to readily sacrifice its tail to predators. This adaptation is associated with characteristic tail behavior and rapid tail regeneration. There is no facultative metabolic increase associated with tail regeneration, and energy normally allocated to body growth and maintenance is diverted to tail regeneration. This supports the contention that tail behavior, autotomy, and rapid regeneration evolved as mechanisms promoting survival in terms of predator escape.

Inhibition of ornithine decarboxylase with 2-difluoromethylornithine: reduced incidence of dimethylhydrazine-induced colon tumors in mice.

2-Difluoromethylornithine (DFMO) was administered to 1,2-dimethylhydrazine (DMH)-treated mice to reduce colonic polyamine levels and mucosal hyperplasia. Mice received 1% DFMO in drinking water throughout the experiment and were given injections of DMH (20 mg/kg) weekly for 28 weeks. DFMO inactivated 93% of colonic ornithine decarboxylase activity. Although DMH treatment did not induce colonic ornithine decarboxylase activity by Week 28, the putrescine content was increased 31% in DMH-treated mice (p less than 0.01). Concurrent treatment with DFMO depressed putrescine content (42 to 63%) and spermidine content (27 to 38%), but it increased spermine content (18 to 22%). At Week 28 of treatment with DMH alone, RNA content was increased 8.6% (p less than 0.01), DNA content 10% (p less than 0.01), DNA specific activity 24% (p less than 0.01), and crypt depth 20% (p less than 0.01), but not in mice receiving DMH and DFMO. At 28 weeks, 13 of 17 mice (76%) treated with DMH alone had histologically confirmed colon cancers; of mice treated with DMH and DFMO, two of 18 (11%) had colonic tumors. Throughout the experiment, 50 colon cancers developed in 16 DMH-treated mice (mean, 3.12 tumors/mouse); three mice treated with DMH and DFMO developed three colon cancers total (p less than 0.001). Reduction of colonic polyamine levels after DFMO treatment prevents proliferative changes induced by DMH and reduces the incidence of tumors.

Increased incidence of tongue cancer after primary radiotherapy for nasopharyngeal carcinoma--the possibility of radiation carcinogenesis.

The aim of this study was to define the risk of tongue and other aerodigestive tract cancers developing after primary radiation therapy for nasopharyngeal carcinoma (NPC). A cohort of 903 patients with non-disseminated NPC given radical radiotherapy between 1984 and 1989 was studied for the incidence of tongue cancer and other malignancies during follow-up. A contemporary cohort of 87 patients with tongue cancer, without a history of NPC, was studied for demographic data, cigarette smoking and alcohol consumption habits. These were then compared with all the NPC patients and with the NPC patients who later developed tongue cancers. There was a significantly increased number of tongue cancers following radiotherapy for NPC. The risk of developing tongue cancer after radiotherapy for NPC was 0.13% per patient per year. There was no increase in the number of other malignancies. The association between NPC and tongue cancer was that of a non-random temporal sequence with tongue cancers following NPC but not in the reverse order. The demographic data and smoking and alcohol consumption history of the 7 NPC patients who subsequently developed tongue cancer were significantly different from the de novo tongue cancer patient population. The absence of common aetiological factors between NPC and tongue cancer and the non-random sequence of tongue cancers occurring after NPC suggests that these seven tongue cancers could be radiation induced. The estimated radiation dose received by the part of the tongue developing cancer was substantial and significantly higher than the dose to the cancer-free tongue. An increase of tongue cancers after radiotherapy for NPC is reported and arguments are made in support of the hypothesis that these were radiation-induced malignancies. We suggest a decrease in the volume of tongue included within the planning target volume of NPC in the absence of oropharyngeal and/or parapharyngeal infiltration. Awareness of the association should make early diagnosis of this likely radiation-induced cancer possible.

Use of esmolol to control autonomic instability of tetanus.

Tetanus is often accompained by autonomic instability, rendering hemodynamic management difficult. Death is frequently secondary to an inability to control this instability. A variety of modalities have been used to stabilize the cardiovascular system, but all are not ideal. Esmolol offers theoretical advantages over other modalities. We report a case of severe tetanus in which a continuous infusion of esmolol was effective in controlling the autonomic instability.

How successful is high-dose (> or = 60 Gy) reirradiation using mainly external beams in salvaging local failures of nasopharyngeal carcinoma?

PURPOSE: To evaluate the efficacy of high-dose (> or = 60 Gy) reirradiation using mainly external beams in salvaging local failures of nasopharyngeal carcinoma (NPC) after modern primary radical radiotherapy that delivered radical dose-to-target volumes defined by CT scan. METHODS AND MATERIALS: Nine hundred and three patients with nondisseminated NPC whose primary radical radiotherapy was administered between 1984 and 1989 inclusive were studied. One hundred and seventy-six had local failures comprising 9 persistences and 167 recurrences. In 10 patients the local failures were preceded or accompanied by (within 2 months) distant metastases, and these were given supportive treatment or palliative radiotherapy in low dose (< 60 Gy) if symptomatic. Most of the rest (123 of 166) were treated with either reirradiation to high dose (> or = 60 Gy) using mainly external photon beams (n = 103) or nasopharyngectomy with/without radical neck dissection with/without postoperative radiotherapy (n = 20). The remainder (n = 43) received only palliative treatments because of poor general condition and/or patients' refusal of radical treatments. The primary radiotherapy was planned on the basis of target volumes defined by CT scan and given to a standard nasopharyngeal dose of 62.5 Gy/29 fractions/6 weeks. In the presence of parapharyngeal involvement, an additional boost of 20 Gy/10 fractions/2 weeks was given via a posterior oblique photon beam. If local residual tumors were diagnosed at 4-6 weeks after the completion of external radiotherapy, an additional boost of 24 Gy/3 fractions/15 days was given by intracavitary intubation. For the local failures given high-dose reirradiation, the target volume was defined by CT scan and treated by a two-field or a three-field photon arrangement with or without additional dose supplement by intracavitary intubation. Nasopharyngectomy was performed via the transcervico-mandibulo-palatal approach or the maxillary swing approach. Radical neck dissection was only performed for the clinically evident nodal failures. RESULTS: With a median follow-up of 20 months (range 2.5-81 months) since the diagnosis of local failure, the actuarial 5-year overall survival, further relapse-free survival and free-from-local-tumor rates were 9.4, 11.5, and 18.7%, respectively, for the 123 patients treated by either high-dose reirradiation (n = 103) or nasopharyngectomy (n = 20). Palliatively treated patients (n = 43) had a survival comparable to patients whose local failures were preceded or accompanied by distant metastasis (n = 10). Reirradiation to high dose (> or = 60 Gy) mainly by external photon beams achieved a 5-year overall survival of 7.6% and 5-year local control of 15.2% with significant complications. Radiation-induced temporal lobe encephalopathy was radiologically evident in 21 patients (20.4%), and 13 of these 21 patients were symptomatic. It could have been the cause of death in three patients who also suffered from uncontrolled local tumor. Significant morbidity was also associated with the other frequent radiation complications, including xerostomia, trismus, and deafness. Uni- and multivariate analyses indicated that brief initial disease-free interval between completion of primary radiotherapy and diagnosis of local failures and advanced recurrent T-stage and recurrent N-stage were significant prognosticators predicting poor survival and/or further local failure after reirradiation. These patients were unlikely to benefit from the treatment. Nasopharyngectomy (+/- neck dissection +/- postoperative radiotherapy) was associated with earlier recurrent T-stages (mostly rT1 and rT2) and better survival and local control than reirradiation. However, restricting the comparison to rT1 and rT2 still demonstrated the superior results in favor of nasopharyngectomy, which could not be explained by the selection of less advanced lesions or patients with better performance status for surgery. (ABSTRACT TRUNCATED)

Anti-proliferative activity of interferon-alpha on human squamous carcinoma of tongue cell lines.

We evaluated the anti-tumour activity of human recombinant interferon-alpha (IFN-alpha) on two human squamous carcinoma of tongue cell lines (T2/CUHK and PWH-S1). The in vitro cytotoxicity was monitored by MTT assay. Continuous exposure to IFN-alpha alone at 500 IU/ml for 48 h produced inhibitory growth of 30% and 7% on T2/CUHK and PWH-S1 cell lines respectively. The ID50 of T2/CUHK cells was approximately 2500 IU/ml. PWH-S1 cells were resistant to treatment with interferon-alpha as 500 IU/ml IFN-alpha gave only 10% growth inhibition on PWH-S1 cells. IFN-alpha increased the anti-neoplastic activity of cisplatin and 5-FU against T2/CUHK cells, but the effect was less evident in PWH-S1 cells. Our findings support the further evaluation of IFN-alpha as a potent anti-proliferative cytokine therapy that may act synergistically with conventional chemotherapeutic agents for the treatment of squamous carcinoma of head and neck.

Total parenteral nutrition inhibits intestinal adaptive hyperplasia in young rats: reversal by feeding.

To determine whether the inhibition of intestinal adaptation by total parenteral nutrition (TPN) in young growing animals is reversible, 130 7-week-old rats with 70% resection of the midportion of the small bowel were given an amino acid and glucose TPN solution parenterally or orally or a chow diet for 10 days. After TPN administration, villous height, crypt depth, DNA and RNA content, RNA:DNA ratio, and sucrase activity were decreased. After returning to 4 weeks of chow feeding, rats given TPN achieved similar body weight and 15% greater intestinal length as compared with rats fed chow from the start, although their jejunal villous height, ileal crypt depth, and RNA:DNA were decreased. Therefore, the inhibition by TPN of intestinal adaptation after intestinal resection in young growing rats is largely reversible. Furthermore, oral feeding of a high-calorie, high-protein liquid diet before feeding of a normal diet appears to promote adaptation after intestinal resection in immature, growing rats.

Establishment and characterization of two new cell lines derived from squamous cell carcinoma of the tongue in Chinese patients.

Two new cell lines derived from squamous cell carcinoma of the tongue, T1/CUHK and T2/CUHK, have been established in culture. Analysis of the morphology, ultrastructure, chromosome number, spheroid formation and immunohistochemical properties of the two cell lines demonstrated that they are both well characterized. T1/CUHK cells grew relatively faster than T2/CUHK cells. Both cell lines were tumorigenic after inoculation into made mice and showed positive reactivity with HPV 16 DNA probe. The reactivity of both cell lines with HPV 18 DNA probe was weak.

Patterns of failure after radical neck dissection for recurrent nasopharyngeal carcinoma.

Radical neck dissection (RND) for recurrent nasopharyngeal carcinoma (NPC) after radiotherapy was retrospectively evaluated in 38 patients treated between April 1986 and December 1991. Thirty patients (79%) had advanced-stage disease. Four patients required nasopharyngectomy as well as RND. The mortality was 0%, and the morbidity was 13%. The actuarial survival rates at 5 years from the time of initial radiotherapy and RND were 50% and 25%, respectively. Of the 21 patients with relapses after surgical salvage, 5 had recurrences in the nasopharynx, 3 had recurrences in the neck, and 13 had distant metastases. We conclude that RND for recurrent NPC is safe and efficacious; however, it is associated with a significant (34%) incidence of distant metastases. These results can be improved by evaluating patients for distant metastases and excluding those with distant metastases. Improvement in the treatment of distant metastases is also needed.

Role of ultrasound in the management of thyroid nodules.

One hundred twenty patients undergoing thyroid surgery for thyroid nodules or goiter were examined by preoperative ultrasound and fine needle aspiration (FNA) cytology. In the determination of whether a lesion was malignant, FNA had sensitivity, specificity, and positive predictive values of 86%, 85%, and 58%, respectively. Ultrasound had sensitivity, specificity, and positive predictive values of 74%, 83%, and 51%, respectively. The different types of thyroid pathology showed different ultrasonic features in most cases, although no single feature was pathognomonic. Malignant lesions tended to be solid and hypoechoic without a halo, but there was a cystic element in 26% of the lesions and calcification in 37%. Ultrasound was superior to FNA in diagnosing nodular goiter with sensitivity, specificity, and positive predictive values of 70%, 93%, and 92%, respectively, compared with 55%, 86%, and 83%, respectively. The two modalities are complementary.

Reversal of biochemical and functional abnormalities in erythrocytes secondary to selenium deficiency.

A patient with multiple enterocutaneous fistulae on total parenteral nutrition for 14 months developed low erythrocyte selenium and low erythrocyte glutathione peroxidase. Erythrocyte hexose monophosphate shunt activity stimulated with an H2O2 generating system was approximately one-fourth that of control. Hexose monophosphate shunt activity stimulated with methylene blue showed little difference between patient and control. With selenium supplementation erythrocyte selenium, glutathione peroxidase, and hexose monophosphate shunt activity became normal. Thus, the biochemical and functional consequences of selenium deficiency can be corrected with selenium supplementation.

Nutritional efficacy and hepatic changes during intragastric, intravenous, and prehepatic feeding in rats.

The nutritional efficacy and hepatic changes in rats given a total parenteral nutrition (TPN) solution consisting of 4.25% amino acids and 25% dextrose by intragastric, intravenous, or prehepatic routes were studied over a 4-day period. Rats fed Purina Chow or given intragastric TPN maintained body weight and showed no appreciable fatty change of liver. In contrast, weight loss, hepatomegaly, and a 37% increase in liver lipid content were observed in rats given intravenous TPN and a 60% increase after prehepatic TPN. Approximately half the rats given intravenous or prehepatic TPN developed fatty changes in the liver. Serum albumin concentration and hepatic protein content were not improved after prehepatic TPN. Serum SGOT and SGPT were elevated in rats given prehepatic TPN only. Prehepatic TPN may result in hepatic injury and offers no apparent benefit over conventional intravenous TPN in rats.

Fat-based (Intralipid 20%) versus carbohydrate-based total parenteral nutrition: effects on hepatic structure and function in rats.

The role of fat-based total parenteral nutrition (TPN) in preventing or ameliorating hepatic dysfunction during TPN was investigated. Adult ACI-N rats were given fat-free carbohydrate-based TPN or isocaloric, isonitrogenous fat-based TPN (50% cal from 20% Intralipid, 50% cal from carbohydrate) for 7 days with Purina Chow-fed and fasting rats as controls. After fat-based TPN as compared with Chow or carbohydrate-based TPN, serum alkaline phosphatase activity and cholesterol levels doubled. Fatty infiltration and periportal inflammation in the liver were more marked. Both the TPN regimens were equally effective in maintaining body weight, positive nitrogen balance, muscle and hepatic protein content. Hepatic dysfunction in rats during TPN was not prevented by using a fat emulsion to provide 50% of the caloric requirement; the optimal proportion of fat as energy substrate in this system is less than 50%.

Total parenteral nutrition with and without fat as substrate for growth of rats and transplanted hepatocarcinoma.

Differential effects of total parenteral nutrition (TPN) on host nutrition and growth of cancer are unclear. Growth of adult ACI-N rats bearing transplanted Morris hepatocarcinoma no. 3924A given TPN with or without fat was studied in comparison with Purina Chow-fed, fasting, and semifasting (either amino acid or dextrose alone) rats over 5 days. The isocaloric, isonitrogenous TPN regimens with or without fat maintained body weight and nitrogen balance of cancer-bearing rats equally well. When compared with Chow-fed rats, the volume of the cancer, its weight, doubling time, protein content, and incorporation of thymidine into DNA were similar in rats given TPN either with or without fat. Although the volume of the cancer decreased in fasting and semifasting rats, the nutritional status of the host was also impaired. Administration of TPN to cancer-bearing rats was associated with an abnormal increase in serum lactic acid level, which was not ameliorated by the use of fat to reduce the carbohydrate load. Although TPN with and without fat maintains the nutritional status, hepatomegaly and hepatic steatosis limit the administration of carbohydrate and fat as energy substrates in this system.

Pediatric burn patients from Vietnamese camps in Hong Kong from 1989 to 1997.

Over the 9 years from 1989 to 1997, many children who suffered from scald burns in the Vietnamese camps in the New Territories of Hong Kong were treated. The profile of these children was examined and analyzed.

Debridement of burn wounds with a surgical ultrasonic aspirator.

Ultrasonic ablation of tissue by the surgical ultrasonic aspirator (SUA) is an established technique in neurosurgery and hepatobiliary surgery. We report the first use of SUA in the debridement of burn wound in three patients. Our initial experience suggested that SUA allows meticulous wound debridement and cleansing with minimal bleeding and destruction of normal tissue and, therefore, is an extremely useful surgical instrument to add to the armamentarium of the burn surgeon.

Acute mass burns caused by o-chlorobenzylidene malononitrile (CS) tear gas.

The use of tear gas in controlling riots has been an accepted practice in many countries for the past four decades. In a recent event, a large quantity of tear-gas canisters were used during a situation of unrest in a Hong Kong Refugees' Detention Centre. We report 96 cases of acute burn injury as an unpredicted side effect of o-chlorobenzylidene malononitrile (CS) tear gas. There were 47 females and 49 males with an age ranging between < 1 to 51 years. These burns were categorized as minor burns, with the total body surface area (TBSA) ranging from 1 to 8 per cent with mean percentage of 3. Most of the patients sustained superficial or partial-skin thickness injuries. Only two patients were admitted to the Prince of Wales Hospital Burns Centre because of deeper burns; debridement and skin grafting was required in one of them. The mechanism of burn injury was due to the flame generated from the grenade explosion, direct contact between the hot canister and the victim's skin, and the effect of the chemical powder inside the canisters when it splashed onto the victim's body. We suggest that the noxious transient effects of tear gas are underestimated, furthermore varying cutaneous effects and deep burns may result from its uncontrolled use during riots. There is a continuing need to reassess the potential toxic effects of CS tear gas as a riot control agent and to debate whether its future use can be condoned under any circumstances.

Burn injuries during paint thinner sniffing.

Thinner sniffing is popular among school children in Asian countries because it is readily available at low cost. Besides its toxicity to major organs, thinner inhalation is associated with various burn accidents. Four teenagers were admitted to the Burns Unit of the Prince of Wales Hospital over the period of 1996-1997. They sustained 3-25% TBSA flame burn and two of them had inhalation injuries as a result of the ignition of a cigarette during thinner sniffing. None of them had evidence of thinner intoxication as shown by blood tests. In the management of their acute burn injuries, their hidden social and family problems were explored. With the cooperation of different disciplines, early psychosocial intervention was given and their behavioral and psychological disturbances were successfully managed.

Evaluation of artificial skin (Integra) in a rodent model.

The biocompatibility of artificial skin (Integra) has been investigated in clean surgical wounds of 20 guinea-pigs. A rectangular 3 x 3 cm full-thickness skin defect with excision carried down to the panniculus carnosus was prepared on the dorsal area of the guinea-pig. A thin layer of silver sulfadiazine cream was applied and artificial skin was placed to cover the wound. At day 14, the uppermost silicone layer was removed. Good take of the artificial skin was observed in 18 of 20 animals. Microscopy showed good vascular ingrowth in 14 of the 18 animals. The remaining four animals showed necrotic tissue, absence of vascularization and haemorrhage in the wound bed. Two of the 20 wounds showed purulent discharge. In this animal model, clinical 'take' of the neodermis was achieved in 18/20 animals (90 per cent), while vascular ingrowth was observed in only 14/20 animals (70 per cent). These results suggested that artificial skin in clean surgical wound is readily biologically incorporated into surrounding viable tissue.

Boiling wax burn in mid-autumn festival in Hong Kong.

An unusual cause of burn, contact with boiling wax by children and adolescents during the annual mid-autumn festival in Hong Kong is presented. 57 patients who suffered from hot wax burn over the period 1986-1996 were admitted to the Burns Unit of the Prince of Wales Hospital. This special burn should be preventable by public education.