Pott's puffy tumour: a rare cause of forehead swelling in a child

We report a case of Pott's puffy tumour in a 12-year-old. Owing to the late development of the frontal sinuses, frontal sinus infection in children is rare. When present it can lead to osteomyelitis associated with forehead swelling. Early diagnosis and active treatment prevent progression to life-threatening intracranial spread.

Management and outcome of choanal atresia correction

OBJECTIVES

Outcome analyses of factors that may either maximize success or predict a better outcome following choanal atresia correction.

METHODS

A retrospective review of children undergoing choanal atresia correction at Great Ormond Street Hospital for Children, London between January 1990 and April 1998. Children with unilateral or bilateral choanal atresia were studied. In all cases, correction was by a transnasal approach under endoscopic control. A 120 degrees Hopkins rod telescope was used to visualize the atretic plate from the nasopharynx. Straight urethral sounds were used to perforate the plate followed by use of an air drill to remove the bony component. Portex endotracheal tubes were subsequently inserted as nasal stents.

RESULTS

Sixty-five children (19 M, 46 F: age range 1 day to 17 years) presented with choanal atresia and the outcomes for 46 were included in the study. Twenty-six patients (40%) had other major anomalies. In children with unilateral atresia neither duration of stenting nor presence of facial anomalies had an impact on outcome. Of those children with bilateral choanal atresia and associated facial anomalies (n=9), 56% were asymptomatic following correction. In children with isolated bilateral choanal atresia (n=19), 74% were asymptomatic following correction; 29% (n2.3 kg (n3. 5 mm (n=6) had an 83% chance of a good outcome. Those patients stented with a tube </=3.5 mm (n=22) had only a 64% success rate. None of the patients who were stented for at least 12 weeks remained symptomatic.

CONCLUSIONS

Neonates with bilateral choanal atresia who were stented for at least 12 weeks with the largest Portex tube that comfortably passed through the anterior nares had the best outcome. If they had either associated anomalies or low weight at surgery, they were less likely to become asymptomatic. For patients with unilateral choanal atresia, neither the presence of facial anomalies nor stent duration had an impact on outcome.

Langerhans' cell histiocytosis--a rare cause of sudden onset unilateral sensorineural hearing loss

Langerhans' cell histiocytosis is a rare disorder of unknown aetiology in which pathological Langerhans' cells accumulate and destroy local tissue. We report a 38-year-old female who presented with a sudden onset of left sensorineural hearing loss. Magnetic resonance imaging (MRI) revealed a contrast-enhancing lesion in the left mastoid and a second lesion in the hypothalamus. Following left mastoid exploration and biopsy a definitive diagnosis of Langerhans' cell histiocytosis was made and the patient was treated with external beam radiotherapy. Subsequent right femur and right mastoid involvement were successfully treated with steroids and cytotoxic chemotherapy. At one year follow-up the patient had residual left-sided sensorineural hearing loss with normal hearing in the right ear. To our knowledge, Langerhans' cell histiocytosis has not been previously reported as a cause of unilateral sudden onset sensorineural hearing loss. It should be considered in the differential diagnosis of this condition.

American Society of Clinical Oncology clinical practice guidelines for the use of chemotherapy and radiotherapy protectants

PURPOSE

Because toxicities associated with chemotherapy and radiotherapy can adversely affect short- and long-term patient quality of life, can limit the dose and duration of treatment, and may be life-threatening, specific agents designed to ameliorate or eliminate certain chemotherapy and radiotherapy toxicities have been developed. Variability in interpretation of the available data pertaining to the efficacy of the three United States Food and Drug Administration-approved agents that have potential chemotherapy- and radiotherapy-protectant activity-dexrazoxane, mesna, and amifostine-and questions about the role of these protectant agents in cancer care led to concern about the appropriate use of these agents. The American Society of Clinical Oncology sought to establish evidence-based, clinical practice guidelines for the use of dexrazoxane, mesna, and amifostine in patients who are not enrolled on clinical treatment trials.

METHODS

A multidisciplinary Expert Panel reviewed the clinical data regarding the activity of dexrazoxane, mesna, and amifostine. A computerized literature search was performed using MEDLINE. In addition to reports collected by individual Panel members, all articles published in the English-speaking literature from June 1997 through December 1998 were collected for review by the Panel chairpersons, and appropriate articles were distributed to the entire Panel for review. Guidelines for use, levels of evidence, and grades of recommendation were reviewed and approved by the Panel. Outcomes considered in evaluating the benefit of a chemotherapy- or radiotherapy-protectant agent included amelioration of short- and long-term chemotherapy- or radiotherapy-related toxicities, risk of tumor protection by the agent, toxicity of the protectant agent itself, quality of life, and economic impact. To the extent that these data were available, the Panel placed the greatest value on lesser toxicity that did not carry a concomitant risk of tumor protection.

RESULTS AND CONCLUSION

Mesna: (1) Mesna, dosed as detailed in these guidelines, is recommended to decrease the incidence of standard-dose ifosfamide-associated urothelial toxicity. (2) There is insufficient evidence on which to base a guideline for the use of mesna to prevent urothelial toxicity with ifosfamide doses that exceed 2.5 g/m(2)/d. (3) Either mesna or forced saline diuresis is recommended to decrease the incidence of urothelial toxicity associated with high-dose cyclophosphamide use in the stem-cell transplantation setting. Dexrazoxane: (1) The use of dexrazoxane is not routinely recommended for patients with metastatic breast cancer who receive initial doxorubicin-based chemotherapy. (2) The use of dexrazoxane may be considered for patients with metastatic breast cancer who have received a cumulative dosage of 300 mg/m(2) or greater of doxorubicin in the metastatic setting and who may benefit from continued doxorubicin-containing therapy. (3) The use of dexrazoxane in the adjuvant setting is not recommended outside of a clinical trial. (4) The use of dexrazoxane can be considered in adult patients who have received more than 300 mg/m(2) of doxorubicin-based therapy for tumors other than breast cancer, although caution should be used in settings in which doxorubicin-based therapy has been shown to improve survival because of concerns of tumor protection by dexrazoxane. (5) There is insufficient evidence to make a guideline for the use of dexrazoxane in the treatment of pediatric malignancies, with epirubicin-based regimens, or with high-dose anthracycline-containing regimens. Similarly, there is insufficient evidence on which to base a guideline for the use of dexrazoxane in patients with cardiac risk factors or underlying cardiac disease. (6) Patients receiving dexrazoxane should continue to be monitored for cardiac toxicity. Amifostine: (1) Amifostine may be considered for the reduction of nephrotoxicity in patients receiving cisplatin-based chemoth

Non-Hodgkin lymphoma diagnosed from a tracheal window biopsy

Images

Carboplatin and paclitaxel for previously treated patients with non-small-cell lung cancer

The chemotherapy regimen of paclitaxel and carboplatin produces an objective response in 30%-60% of patients with non-small-cell lung cancer (NSCLC). In a prospective study, we administered paclitaxel 200 mg/m2 (by 1-3-hr infusion) and carboplatin at an area under the plasma concentration curve (AUC) of 5 (by the Calvert formula) every 3 weeks to 21 patients who had previously received predominantly platinum-based chemotherapy for NSCLC. We observed no objective responses. Patients received a median of 2 cycles before disease progression. Three of 5 patients who had received only single-agent treatment with a relatively inactive agent may have had modest clinical benefit. We conclude that the paclitaxel/carboplatin regimen has minimal activity in previously treated patients with NSCLC.

Oat cell carcinoma of the tongue from an unknown primary

Oat cell carcinoma is rarely diagnosed in the head and neck and can be primary or secondary. Primary tumors arise from amine precursor uptake and decarboxylation cells which are found throughout the head and neck. Secondary deposits metastasize most commonly from the lungs. We report a 64-year-old woman with a known pancreatic oat cell carcinoma who came to the ENT Department with dysphagia. On examination, a lesion was seen at the base of the tongue and was histologically an oat cell carcinoma. No treatment was administered and the patient died one month after discharge. This report highlights the difficulty in determining the primary site when a rare tumor metastasizes to the head and neck and no autopsy findings are obtained. To our knowledge, oat cell carcinoma of the tongue has not been previously reported.

The management of asymptomatic firearm injuries in children

Paediatric firearm injuries in the UK are uncommon. We present two children with BB-gun pellets in the parapharyngeal space who were managed conservatively and remained asymptomatic 6 months after the gunshot injury. The management of asymptomatic firearm injuries in children is discussed and a literature review included.

Tuberculous lymphadenopathy masquerading as a bronchial foreign body

A case of recent onset of wheezing with clinical and radiologic findings suggestive of foreign body aspiration is presented. Rigid bronchoscopy revealed an extraluminal compression of the airway. Histopathologic and microbiologic examination revealed tuberculous lymphadenopathy.

Pediatric functional endoscopic sinus surgery: is a second look necessary?

Functional endoscopic sinus surgery (FESS) has become the surgical procedure of choice for the treatment of chronic sinusitis that is refractory to medical treatment. It has become routine to perform endoscopy in children under general anesthesia 2 to 3 weeks after FESS to facilitate examination and cleaning of the operative site. We compared the clinical outcome of 50 children who underwent FESS without a second-look endoscopy with 50 children who underwent a routine second look. Patients with systemic disease (cystic fibrosis, immotile ciliary syndrome, immunoglobulin deficiency) or undergoing a revision procedure were excluded from the study. The results show that the postoperative improvement in nasal obstruction, nasal drainage, and chronic cough was the same for both groups. We conclude that in the vast majority of children without systemic disease and not undergoing a revision procedure, a second endoscopic procedure may not offer any apparent advantage.

Pseudoaneurysm of the right lingual artery: an unusual cause of severe hemorrhage during tonsillectomy

Profuse intraoperative hemorrhage is an uncommon complication of tonsillectomy. We present a three-year-old girl who underwent a routine adenotonsillectomy during which massive bleeding occurred from a large vessel in the right tonsillar fossae. Angiography revealed an aberrant right lingual artery with a pseudoaneurysm. The right lingual artery was embolized with multiple coils and the bleeding was halted. The causes and treatment of extracranial carotid artery pseudoaneurysms are discussed.

Outpatient adenotonsillectomy. Is it safe in children younger than 3 years?

OBJECTIVE

To evaluate the safety of ambulatory adenotonsillectomy in children younger than 3 years.

MATERIALS AND METHODS

The records of 102 children younger than 3 years who underwent adenotonsillectomy as an outpatient procedure were reviewed during a 3-year period.

RESULTS

Ten patients (10%) required overnight hospital admission for an average of 1.4 days. Nine patients were admitted directly from the day-stay unit and 1 patient was admitted 48 hours after surgery. The reason for hospital admission was poor oral intake. None of the patients had postoperative bleeding or respiratory problems or required intensive care unit admission.

CONCLUSION

The safety of ambulatory adenotonsillectomy depends on judicious selection criteria and can be performed in children younger than 3 years.

Subglottic stenosis complicating cardiac surgery in children

OBJECTIVE

To highlight the incidence of subglottic stenosis (SGS) as a complication of surgery for congenital heart disease and the role of single-stage laryngotracheoplasty in treating this complication.

DESIGN

Retrospective case series.

SETTING

University-based referral center specializing in surgery for congenital heart disease and complex airway problem management.

INTERVENTION

Laryngotracheal reconstruction (LTR).

MAIN OUTCOME MEASURE

Successful airway expansion.

RESULTS

At last follow-up, 87.5% (7 of 8) of patients remain free of obstructive airway symptoms.

CONCLUSION

SGS can complicate surgery for congenital heart disease in children. Single-stage LTR is an effective treatment modality for this problem.

Peritonsillar abscess in early childhood. Presentation and management

OBJECTIVE

To highlight the modes of presentation and management of a peritonsillar abscess in children younger than 5 years.

DESIGN

Retrospective case series.

SETTING

Tertiary referral pediatric otolaryngology practice.

PATIENTS

Seven children younger than 5 years.

RESULTS

The mean age of the children studied was 27 months (age range, 7-41 months). Five (71%) of the 7 patients underwent computed tomographic scanning to confirm the diagnosis. Pus was cultured at surgery in every case. The most common organism detected was Streptococcus viridans. The average hospital stay was 72 hours (range, 22 hours to 12 days). After diagnosis of an abscess, all patients underwent an electrocautery tonsillectomy and had an uneventful recovery.

CONCLUSIONS

Children younger than 5 years who present with poor oral intake, high fever, drooling, and trismus should be suspected of having a peritonsillar abscess. A computed tomographic scan of the neck is usually required to confirm a suspected diagnosis. Prompt diagnosis and treatment will lead to a considerable decrease in morbidity. Immediate tonsillectomy is a safe and effective means of abscess drainage.

Relationships between in situ protein degradability and grass developmental morphology

The objective of this research was to determine the relationships between the morphological development and in situ ruminally degradable protein (RDP), ruminally undegradable protein (RUP), and microbial protein of two cool season grasses (intermediate wheatgrass and smooth bromegrass) and two warm season grasses (switchgrass and big bluestem). The initial growth of grass tillers grown near Mead, Nebraska was clipped at ground level six times during the 1992 growing season and morphologically classified. Mean stage was calculated. Forage was ground to pass a 2-mm screen and was incubated in ruminally fistulated steers for 16 h. The RUP was adjusted for microbial protein and acid detergent insoluble N. The mean stage of cool season grasses was higher than that of warm season grasses throughout the growing season. The RDP decreased as plant maturity increased for all species. The RUP expressed as a percentage of crude protein for the cool season grasses was lower than that for warm season grasses. The RUP for intermediate wheatgrass, smooth bromegrass, and switchgrass remained constant across maturities, but RUP for big bluestem decreased as maturity increased. Microbial augmentation of RUP decreased as crude protein decreased in all species. The RUP corrected for acid detergent insoluble N and microbial protein was relatively constant across plant maturities. The quantification of RUP across a range of plant maturities provided information for incorporating RUP content of forage grasses into the diets of animals.

Fat graft myringoplasty in children--a safe and successful day-stay procedure

The surgical closure of dry tympanic membrane perforations in children remains a controversial issue due to conflicting opinions on the appropriate technique, graft material and success rate. We present a review of 342 children who underwent fat graft myringoplasty as a day-stay procedure over a six-year period. Successful closure of the tympanic membrane perforation was achieved in 92 per cent of ears. Subsequent recurrent otitis media with effusion required insertion of ventilation tubes in 12 per cent. No relationship was observed between the age of the child and a successful outcome. We conclude that day-stay fat graft myringoplasty is a safe and successful procedure which results in a dry and safe ear in the majority of children.

Management of medial subperiosteal abscess of the orbit in children--a 5 year experience

A medial subperiosteal abscess (SPA) of the orbit is the most common serious complication of sinusitis in children. The distinction between SPA and the more benign pre-septal disease is difficult to make especially in a young child in whom an ophthalmological evaluation is often difficult. Computerised tomography (CT) is the investigation of choice in making this distinction. Subperiosteal inflammatory disease of the orbit is initially treated with intravenous antibiotic therapy with surgery reserved for those patients who do not respond to medical treatment and in whom a medial SPA is confirmed by CT. Conventionally, the abscess is drained via an external incision and an ethmoidectomy is performed at the same time. More recently, successful drainage of SPA's has been accomplished endoscopically via a intranasal approach with less morbidity and superior cosmesis. We present a 5 year experience of 24 patients with CT scans suggestive of medial SPA who underwent endoscopic exploration of the medial subperiosteal orbital space. We discuss the current management of medial subperiosteal disease of the orbit in children and include a review of the literature. Also included is a clinical staging system which aids the management of orbital complications of sinusitis.

Campomelic syndrome--laryngotracheomalacia treated with single-stage laryngotracheal reconstruction

The campomelic syndrome is a rare osteochondrodysplasia which frequently leads to early death from pulmonary insufficiency. We describe a patient with anatomic compromise of the upper airway due to diffuse laryngotracheomalacia and a moderate subglottic stenosis, treated successfully with single-stage laryngotracheal reconstruction using a rib graft. To our knowledge this has not been previously described. A review of the current literature is included.

Bilateral fat graft myringoplasty in children

The results after simultaneous bilateral fat graft myringoplasties in children have not been previously reported in the literature. We report on 28 children who underwent bilateral fat graft myringoplasties as outpatient procedures under general anesthesia. The success rate was 91% at final follow-up, with only 16% of children requiring insertion of pressure-equalizing (PE) tubes following surgery. No complications were documented. We concluded that bilateral fat graft myringoplasties are safe to perform, with an excellent success rate, and are suitable as outpatient procedures.

Day-stay tonsillectomy: is hospital stay reduced at the expense of increased community care?

There is concern about the burden day-stay surgery created upon community services. We have followed 128 children and 38 adults undergoing day-stay tonsillectomy and a similar cohort of adults and children undergoing tonsillectomy as inpatients and looked at the demands made on general practice and casualty services over the 2 weeks after discharge. Twelve adults (18%) and four children (3%) required overnight admission after day-stay surgery. Within the first 2 weeks, 27 adults (48.2%) and 62 children (50%) visited their GP and 13 adults (23.2%) and six children (4.8%) visited the casualty department. There was no statistically significant difference for either adults or children when comparing the day-stay and inpatient cohorts. Adult day-stay tonsillectomy is associated with a high admission rate. Both adult and paediatric tonsillectomy lead to considerable demand for general practice and casualty services, but this demand is high regardless of whether the day-stay or inpatient route is chosen.

Sequential therapy with dacarbazine and carmustine: a phase I study

Depletion of the DNA-repair protein O6-alkylguanine-DNA alkyltransferase (AGT) increases the sensitivity of cells in culture and of human tumor xenografts to chloroethylnitrosoureas such as carmustine (BCNU). We have previously demonstrated that dacarbazine (DTIC) can deplete AGT activity in cells in culture and in human tumor xenografts. A phase I trial of DTIC followed immediately by BCNU was conducted to determine the DTIC dose resulting in maximal depletion of AGT in the peripheral blood mononuclear cells (PBMC) of cancer patients and to determine the maximally tolerated dose of DTIC given as a 4-h infusion immediately prior to a fixed dose of BCNU. A 4-h infusion of DTIC followed by a 2-h infusion of BCNU was given to 42 patients with refractory solid tumors. Complete depletion of AGT activity was not achieved at DTIC doses of up to 750 mg/m2. The dose-limiting toxicity was hematologic, although at higher doses of BCNU (> or = 100 mg/m2) we observed significant nonhematologic toxicity. Our recommended phase II doses are 1,000 mg/m2 DTIC followed by 75 mg/m2 BCNU. AGT activity in PBMC of the 28 patients studied decreased to a mean of 62% +/- 11% (SE) of the baseline value at 4 h after initiation of the DTIC infusion. At 24 h after initiation of the DTIC infusion, AGT activity in PBMC was depleted to a mean of 65% +/- 14% of the baseline value. There was no direct correlation between the DTIC dose and the extent of AGT depletion. Baseline PBMC AGT levels varied widely among patients.

Syphilis as AIDS?--A call for research

Based upon a literature survey, this paper outlines the argument that Treponema pallidum may be the etiologic agent of AIDS. AIDS and syphilis have similar epidemiology, immunology and pathologies. In addition, the current methods of detecting and treating syphilis are inadequate. The similarities between syphilis and AIDS support the need for further research into their relationships, including the role Treponema pallidum may play in AIDS etiology.

Effect of temozolomide and dacarbazine on O6-alkylguanine-DNA alkyltransferase activity and sensitivity of human tumor cells and xenografts to 1,3-bis(2-chloroethyl)-1-nitrosourea

We investigated the ability of 5-(dimethyltriazeno)imidazole-4-carboxamide (DTIC, decarbazine) and an analogue, temozolomide, to deplete cells or tumors of O6-alkylguanine-DNA alkyltransferase (AGT) and to enhance the antitumor effects of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). Human colon cancer (HT29) cell survival was decreased by almost 1 log when treated with 500 microM temozolomide prior to 150 microM BCNU. Administration of the maximal tolerated dose of DTIC (300 mg/kg) to nude mice carrying HT29 xenografts resulted in complete depletion of AGT activity in tumors at 4 h and 16 h. Administration of 150 mg/kg DTIC caused a 76% reduction in AGT activity at 4 h, but only a 28% reduction at 16 h. The maximally tolerated doses of DTIC and BCNU, alone and in combination, were used to treat nude mice bearing HT29 xenografts. No difference in tumor growth occurred when animals were treated with either BCNU alone (50 mg/kg), DTIC alone (300 mg/kg), DTIC (150 mg/kg) followed by BCNU (12.5 mg/kg), or BCNU (25 mg/kg) followed by DTIC (150 mg/kg). These data suggest that methylating agents such as DTIC may be too toxic to be used in combination with BCNU to deplete tumor alkyltransferase levels effectively and increase the therapeutic index of BCNU.

Effect of O6-benzylguanine on the sensitivity of human tumor xenografts to 1,3-bis(2-chloroethyl)-1-nitrosourea and on DNA interstrand cross-link formation

We have previously shown that O6-benzylguanine can be used to deplete cells of the DNA repair protein O6-alkylguanine-DNA alkyltransferase and to enhance the sensitivity of human glioma (SF767) and colon tumor (HT29) cells to the cytotoxic effects of alkylnitrosoureas. In the present study, the combination of O6-benzylguanine and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was evaluated in vitro to determine the number of DNA interstrand cross-links formed and in vivo to compare the therapeutic index with that of BCNU alone. The number of DNA interstrand cross-links, as measured by alkaline elution, was increased in HT29 cells treated with 10 microM O6-benzylguanine for 2 h prior to BCNU exposure compared to cells treated with BCNU only. The number of single strand breaks was not increased by prior exposure to O6-benzylguanine. To evaluate the therapeutic index, HT29 and SF767 cells were grown as xenografts in nude mice and the tumor growth rate after treatment with BCNU alone was compared with the rate after treatment with O6-benzylguanine and BCNU. Treatment was administered i.p. when tumors reached 100-200 mm3. For animals bearing HT29 xenografts that were treated with 60 mg/kg O6-benzylguanine 1 h prior to 20 mg/kg BCNU, the average time for tumor volume to increase by 200% was 25 days, compared to 10 days for animals treated with 20 mg/kg BCNU alone. For animals bearing SF767 xenografts, the tumor growth of controls was not significantly different from that of animals treated with O6-benzylguanine alone or BCNU alone up to the maximally tolerated dose (50 mg/kg). For these 3 groups, the average time for tumors to reach 300 mm3 was 9-12 days. However, when animals were treated with 80 mg/kg O6-benzylguanine 1 h prior to receiving 20 mg/kg BCNU tumor size did not increase for at least 21 days. Our studies demonstrate that the therapeutic index of BCNU can be increased when given in combination with O6-benzylguanine.

Changes in HS mouse erythrocyte mass and area with respect to donor age

Interferometric photographs of blood smears from heterogeneous stock (HS) mice were analyzed for age-related changes in erythrocyte mass using quantitative cytophotometry. Blood smears were obtained from 96 mice (half male/half female) sacrificed at 172, 272, 374, 482, 581, and 664 days of age as part of a larger biomarkers of aging study. Blood smears from each animal were photographed with a Leitz Mach-Zehnder interferometer, and the erythrocyte images on these negatives were measured for dry mass using a Vickers M85a microdensitometer. Cell area measurements were made from a video-microscope image traced with a computer digitizer. Results indicated that animals from middle-age groups (272, 374, and 482 days) have higher red blood cell mass than animals at either young (172 days) or older (581 and 664 days) age groups. Mass changes with respect to age followed similar trends when data were further examined with regard to sex of the animals. Erythrocyte area measurements showed a general age-related decrease in cell size.

Effect of O6-benzylguanine analogues on sensitivity of human tumor cells to the cytotoxic effects of alkylating agents

The effect of O6-benzylguanine, O6-(p-chlorobenzyl)guanine, and O6-(p-methylbenzyl)guanine on the sensitivity of various human tumor cell lines to alkylating agents is evaluated. The sensitivity of human colon tumor cells, HT29, to the chloroethylating agents, 1,3-bis(2-chloroethyl)-1-nitrosourea, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, 2-chloroethyl(methylsulfonyl) methanesulfonate (clomesone), and chlorozotocin was increased by pretreatment for 2 h with 25 microM of each analogue. O6-Benzylguanine was slightly more effective as a sensitizer in HT29 cells than the p-chlorobenzyl and p-methylbenzyl analogues. However, all analogues sensitized SF767 glioma cells to the cytotoxic effects of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, 1,3-bis(2-chloroethyl)-1-nitrosourea, and clomesone to the same degree. Both cell lines were sensitized to the methylating agents streptozotocin and 5-(3-methyl-1-triazeno)imidazole-4-carboxamide, the active intermediate of 5-(3,3-dimethyl-1-triazenyl)imidazole-4-carboxamide, by pretreatment with 10 microM O6-benzylguanine for 2 h. The number of Raji cells surviving 50 microM clomesone decreased 3-fold upon pretreatment for 2 h with 1 microM O6-benzylguanine. The degree of enhancement was dependent on the amount of alkyltransferase protein present in cell lines. For example, HT29 cells (alkyltransferase activity, 381 fmol/mg protein) exhibited a greater degree of enhancement when treated with O6-benzylguanine than SF767 (77 fmol/mg protein) and M19-MEL melanoma (36 fmol/mg protein) cells. There was no enhancement observed in mer- cell lines, U251 (less than 2 fmol/mg protein), and BE (3 fmol/mg protein), or with alkylating agents which did not produce a cytotoxic lesion at the O6 position of guanine in DNA such as cisplatin or 4-hydroperoxycyclophosphamide. Our studies suggest that O6-benzylguanine analogues may have utility in mer+ tumors as an adjuvant to a variety of alkylating agents which produce a toxic lesion at the O6 position of guanine.

Modulation of mammalian O6-alkylguanine-DNA alkyltransferase in vivo by O6-benzylguanine and its effect on the sensitivity of a human glioma tumor to 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea

Experiments were carried out in mice and hamsters to determine whether the activity of the DNA repair protein, O6-alkylguanine-DNA alkyltransferase, in tissues and tumors was reduced by treatment with O6-benzylguanine in vivo. Following intraperitoneal injection of O6-benzylguanine, there was a rapid and complete loss of alkyltransferase activity in both livers and kidneys of mice and hamsters. The activity in mouse tissues was slowly restored, reaching pretreatment activities at 16 hr and 72 hr after injection of O6-benzylguanine at 10 mg/kg or 126 mg/kg, respectively. The activity in hamster liver was restored at a significantly lower rate, reaching less than 20% pretreatment activity 72 hr after treatment with 100 mg/kg of O6-benzylguanine. The efficient reduction of alkyltransferase activity by O6-benzylguanine was in sharp contrast to the inability of O6-methylguanine to bring about similar reductions. Activities dropped to about 55% of pretreatment activities in several mouse organs 4 hr after treatment with 126 mg/kg of O6-methylguanine compared to a more than 90% reduction in activity in animals after treatment with O6-benzylguanine. The sensitivity of SF767 cells to meCCNU after treatment with O6-benzylguanine was increased substantially. Furthermore, treatment of nude mice carrying SF767 tumor with 60 mg/kg of O6-benzylguanine prior to either 7.5 or 15 mg/kg of meCCNU led to significant inhibition of tumor growth. These studies indicate that O6-benzylguanine is a suitable compound for use in experiments to examine the role of the alkyltransferase protein in vivo in counteracting the effects of alkylating agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Syndrome of idiopathic hyperammonemia after high-dose chemotherapy: review of nine cases

PURPOSE

The syndrome of idiopathic hyperammonemia occurs in patients who have received high-dose cytoreductive therapy for the treatment of hematologic malignancy. It is characterized by abrupt alteration in mental status and respiratory alkalosis associated with markedly elevated plasma ammonium levels in the absence of any identifiable cause, and frequently results in intractable coma and death. Our goal was to survey clinical and pathologic manifestations of the disorder and discuss treatment options.

PATIENTS AND METHODS

Plasma ammonium levels were measured in patients on the acute leukemia service or on the bone marrow transplant service at The Johns Hopkins Hospital, and a level more than twice normal was considered diagnostic of hyperammonemia. The syndrome was identified in nine patients; in eight, hyperammonemia occurred after administration of intensive cytoreductive therapy that resulted in profound leukopenia. The disorder occurred in the ninth patient two months after allogeneic bone marrow transplantation.

RESULTS

Three of the nine patients survived an episode of idiopathic hyperammonemia; one patient subsequently died of leukemia and one of recurrent idiopathic hyperammonemia. The one long-term survivor is currently alive and well without neurologic sequelae 250 days after autologous bone marrow transplantation.

CONCLUSION

Because neurologic function can deteriorate rapidly, early recognition of this disorder and close monitoring of the patient's neurologic status are critical.

Differentiation of normal marrow and HL60 cells induced by antithymocyte globulin

Antithymocyte globulin (ATG) therapy is an important treatment alternative for patients with acquired aplastic anemia. The mechanism by which it exerts its effects on hematopoiesis is unknown. In this report, we describe the ability of horse ATG to induce growth and differentiation of normal bone marrow. A single cell suspension of normal human bone marrow was cultured in methylcellulose medium and examined for the growth and maturation after incubation with ATG (10 micrograms/ml). After 3-4 days of culture, spherical colonies containing mature myeloid elements were found in cultures containing ATG but not in cultures containing medium or preimmunization horse IgG. The addition of 10% colony-stimulating factor increased growth by 40%. The number of spherical colonies is not dependent on the presence of macrophages or T lymphocytes. This property of ATG may be relevant to the mechanism behind the hematologic recovery in some patients with acquired aplastic anemia. We also describe the ability of ATG to induce terminal differentiation in the HL60 leukemic cell line. ATG binds to HL60 cells and at concentrations between 10 and 100 micrograms/ml, 50% of the cells become mature granulocytes, acquire the ability to reduce nitroblue tetrazolium, and lose their proliferative capacity in the clonogenic assay. These new observations of ATG-induced differentiation of normal marrow myeloid elements and terminal differentiation of the HL60 cell line point to different avenues for future search of differentiation-inducing agents.

Histochemical assessment of nuclear protein content and enzyme activity in confluent nonarrested and low-serum arrested WI-38 fibroblasts at mid and late population doubling levels

Cultures of WI-38 fibroblasts maintained in low-serum medium have little mitotic activity. Such arrested cultures can serve as a useful adjunct to the normal-serum proliferating fibroblast model system of senescence since the reduced cycling activity more accurately reflects in vivo conditions. Normal-serum plateau phase cultures and 17-day low-serum arrested plateau phase cultures were examined at both mid and late population doubling levels (PDL). Acidic, basic and total nuclear protein contents were determined by staining with toluidine blue O, alkaline fast green and acid fast green, respectively. Succinate dehydrogenase and glucose-6-phosphate dehydrogenase were localized with the nitroblue tetrazolium staining reaction. Quantification of individual cell staining was done on a Vickers M85 microdensitometer. Low-serum arrested cells at both mid and late PDL showed a significant increase in acidic protein staining and a decrease in basic protein staining when compared with normal-serum nonarrested cells. Enzyme activities in arrested cells were lower than nonarrested cells at mid PDL but equivalent to nonarrested cells at late PDL. This study demonstrates that the use of selected quantitative histochemical staining in combination with cytophotometry can be employed to differentiate arrested from nonarrested fibroblast populations as well as mid PDL from late PDL cultures.

Hydrocortisone effects on nucleic acid and nuclear protein content and protein metabolism in aging WI-38 cells

Confluent late passage WI-38 human diploid fibroblast cultures grown in the presence or absence of hydrocortisone for fifteen population doublings were measured cytochemically for DNA, nuclear RNA, basic nuclear protein and acidic nuclear protein content during a 12-hour interval following a medium-change stimulation. Radioisotope tracer studies were utilized to assess the effects of prolonged hydrocortisone treatment on protein synthesis and degradation in aging confluent and logarithmically growing cultures. Hydrocortisone-treated cultures exhibited an increased Feulgen--DNA stainability, no difference in basic nuclear protein content, a significantly larger initial decrease followed by an increase in acidic nuclear protein content, and elevated levels of nuclear RNA as compared to untreated controls. Hydrocortisone treatment also resulted in increased incorporation of leucine into protein and decreased breakdown of pre-labeled protein in both confluent and logarithmically growing cultures. These results indicate that many of the metabolic changes associated with proliferation are stimulated by prolonged hydrocortisone treatment of late passage WI-38 fibroblast cells.

Age-related changes in brain RNA of noise stressed mice

Correlative data were obtained on RNA levels of cerebrocortical neurons, adrenal fasciculate cell RNA content and serum corticosterone levels in 10, 40 and 100 week old male C57BL/6J mice immediately following a 30 interval of continuous noise stimulation (100 dB re 2 x 10(-5) N/m2, 0.35-20 kHz) and at 1 hr and 4 hr recovery intervals. Quantification of cellular RNA levels entailed use of scanning-integrating microdensitometry of azure B stained tissue sections. Hormonal analyses were done by radioimmunoassay. Noise stimulation induced a mild to moderate adrenocortical activation and a moderate elevation of serum corticosterone levels in all age groups. Noise exposure also resulted in an increase in the RNA content of cerebrocortical neurons. However, maximal neuronal RNA levels proved to be considerably lower (32-36%) in 100 week old mice as compared to both 10 and 40 week old mice during the post-exposure intervals. The overall data support the existence of a lower neuronal capacity for sensory induced RNA synthesis in 100 week old mice. The data also suggest that age dependent differences in neuronal responsiveness are not directly related to the extent of adrenal RNA activation or to a lower availability of circulating glucocorticoids.

Cytophotometric identification of tetraploid Purkinje cells in young and aged rats

DNA content of cerebellar basket and Purkinje cells of four month, one year, and two year old albino rats was determined by Feulgen cytophotometry. DNA content per nucleus remained essentially constant during aging although there was a slight shift to lower Feulgen-DNA values occurring in the one year age group. Purkinje cells of all three age groups were found to contain tetraploid amounts of DNA as compared to diploid basket cells.

Microorganisms of the upper atmosphere. II. Microorganisms in two types of air masses at 690 meters over a city

The viable micropopulation found, at altitude over a city, in a land air mass was significantly higher than that found in a marine-influenced air mass. The percentage distribution of bacteria and fungi was approximately equal in both types of air masses. This indicates that, under the conditions of the experiment, the marine air mass was influenced by the land area over which it traveled during passage from its source to the sampling area. Activities taking place within the city significantly increased the micropopulation at altitude. This increase was quantitatively so small that it was not identifiable when the micropopulation moving into the city was high-as in a land air mass-but was recognizable when the micropopulation was low-as in a marine-influenced air mass. The modification of the micropopulation at altitude by temperature inversions was shown.