Modulation of humoral and cell-mediated immune responses by Azadirachta indica (Neem) in mice

The effects of A. indica (AI, Neem) were evaluated on tests of humoral and cell-mediated immune responses after 3 weeks of oral AI (leaf extract) treatment in ovalbumin immunized mice. At the dose levels tested, AI (10, 30 or 100 mg/kg), had no appreciable influence on different organ (liver, spleen, thymus)/body weight indices, when compared to controls. In tests for humoral immune responses, AI (100 mg/kg) treated mice had higher (1) IgM and IgG levels, and (b) anti-ovalbumin antibody titres, when compared to the vehicle treated group. In tests for cell-mediated immune responses, there was an enhancement (%) of (a) macrophage migration inhibition, and (b) footpad thickness after AI (100 mg/kg) treatment. These results are discussed in light of the possible immunopotentiating effects of AI.

The effects of an RNA synthesis inhibitor on the survival and regeneration of rat motoneurones injured at birth

This preliminary study aimed to test the proposal that neuronal death is triggered by expression of specific genes. In rat pups, the sciatic nerve was injured unilaterally on the first day after birth and actinomycin D, an RNA synthesis inhibitor, was administered 3 days later in a lower and higher dose to rat pups just prior to onset of motoneurone death induced by the lesion. Four weeks later, sciatic motoneurones from operated and contralateral pools were counted and their size measured. Significantly fewer motoneurones (16.7% +/- 2.9 SD) survived when the animals were treated with a lower dose of the inhibitor compared to saline treated controls (36.6% +/- 12.7 SD). Experiments recording tension generated in soleus muscle in response to sciatic nerve stimulation, at different ages following nerve crush, suggested that the treatment with the RNA synthesis inhibitor may have delayed regeneration of motor axons back to the muscle. However, survival of motoneurones after treatment with the higher dose did not differ significantly from controls (27.5% +/- 1.3 SD). Nevertheless, the higher dose significantly reduced growth of motoneurones after 4 weeks. Therefore, the higher dose, although impeding normal development of motoneurones, is less neurotoxic than a lower dose. This suggests that a balancing of conflicting effects may have occurred. The neurodegenerative effects of delayed reinnervation induced by RNA synthesis inhibition may be balanced by some neuroprotective effects at a higher dose. More extensive studies are required to validate these pilot findings.

Antinociceptive action of Azadirachta indica (neem) in mice: possible mechanisms involved

Azadirachta indica (AI, Neem) was tested for analgesic potency in experimental pain models in mice. In the glacial acetic acid (GAA) induced writhing test, AI (10, 30 and 100 mg/kg) dose-dependently reduced both the incidence and the number of writhes. Similarly, AI, at the dose levels tested, also enhanced tail withdrawal latencies in the tail-flick test for nociception. In the interaction studies, pretreatment with the opioid antagonist, naloxone (1 mg/kg) and the central noradrenaline depleter, DSP-4 (50 mg/kg) attenuated AI analgesia by differential degrees in both experimental models, whereas, the serotonin synthesis inhibitor, PCPA (300 mg/kg) potentiated the same. These results suggest that both central and peripheral mechanisms and complex neural pathways, opioid and non-opioid, may be involved in AI induced analgesia.

Corticosteroid-induced asthma: a manifestation of limited hyperinfection syndrome due to Strongyloides stercoralis

Inadequate therapeutic response to parenteral corticosteroids in patients with acute bronchial asthma is infrequent. We report four patients whose bronchial asthma symptoms worsened after treatment with parenteral corticosteroids. All had larvae of Strongyloides stercoralis in the stool. The new attack or the exacerbation of asthma appeared to be precipitated by systemic corticosteroid administration. The paradoxic therapeutic response of asthma to glucocorticoides was the major pulmonary manifestation of Strongyloides superinfection; there was no evidence of other organ involvement. Individuals with new onset of bronchial asthma or worsening of asthmatic episodes concurrent with the use of systemic corticosteroids should have thorough investigation for possible superinfection due to Strongyloides stercoralis. This is particularly important for patients who have resided in areas where intestinal helminthic infections are endemic. Discontinuance of steroid therapy or reduction in dosage of parenteral steroids appears necessary. Treatment with thiabendazole appears to be effective in patients with limited hyperinfection syndrome.

Fat and oil inhibit phosphine release from aluminium phosphide--its clinical implication

Poisoning by suicidal or accidental ingestion of aluminium phosphide (AlP) is a frequent medical emergency seen all over the world. AlP, a grain fumigant and rodenticide, on exposure to moisture, liberates highly toxic gas, phosphine. The rapidly inhibits mitochondrial respiration and has cytotoxic action. No specific antidote is known against it till date and prognosis depends much on dose and time lag between AlP ingestion and the stomach wash in the hospital (critical period). Physicochemical properties of AlP and nonmiscibility of fat and water promoted us to study the effect of different fats and oils as possible antidotes to inhibit phosphine liberation. In vitro experiments revealed that vegetable oils and liquid paraffin were much more effective than butter and ghee in inhibiting release of phosphine from AlP. These findings may have significant clinical implication.

Role of dopaminergic mechanisms in the regulation of stress responses in experimental animals

The effects of some dopaminergic agents were evaluated on stress responses in normal and immunized experimental animals. Restraint stress (RS) consistently induced gastric mucosal lesions and elevated plasma corticosterone in rats. Pretreatment with alpha-methyltyrosine (alpha-MT), haloperidol, or sulpiride aggravated both responses, whereas bromocriptine attenuated them. In rats immunized with sheep red blood cells (SRBCs), RS prevented the booster-induced rise in anti-SRBC antibody titre. This response was further suppressed by alpha-MT, haloperidol, or sulpiride pretreatment, whereas bromocriptine potentiated the humoral immune response. In mice immunized with SRBCs, antigen challenge-induced increase in footpad thickness was inhibited by RS. Similar inhibitions in this response were also seen after alpha-MT or haloperidol treatment. The results are discussed in light of complex dopaminergic mechanisms in the regulation of visceral, endocrinological, and immune responses during stress.

Microdissected double-minute DNA detects variable patterns of chromosomal localizations and multiple abundantly expressed transcripts in normal and leukemic cells

Double-minute (dm) chromosomes are cytogenetically resolvable DNA amplification-mediating acentric extrachromosomal structures that are commonly seen in primary tumors, tumor cell lines, and drug-resistant cells grown in vitro. Selective isolation of dm DNAs with standard molecular biological techniques is difficult, and thus, detailed studies to elucidate their structure, site of chromosomal origin, and chromosomal reintegration patterns have been limited. In those instances in which a gene has been localized on dms, characterization of the remainder of the DNA, which far exceeds the size of the gene identified, has remained inconclusive, dms seen in the acute myeloid leukemia cell line HL-60 have been shown to harbor the c-myc protooncogene. In this paper, we report the successful isolation of the dm-specific DNAs from these cells by the microdissection/polymerase chain reaction technique and demonstrate that the dm DNAs derived from a single discrete normal chromosome segment 8q24.1-q24.2 reintegrate at various specific locations in the leukemic cells. The microdissected dm DNA detects multiple abundantly expressed transcripts distinct from c-myc mRNA on Northern blots. By devising a "transcript selection" strategy, we cloned the partial genomic sequence of a gene from the microdissected DNA that encodes two of these RNAs. This strategy will be generally applicable for rapid cloning of unknown amplified genes harbored on dms. With DNA from 20 microdissected dms, we constructed a genomic library of about 20,000 recombinant microclones with an average insert size of about 450 bp.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchiolitis obliterans organizing pneumonia associated with massive L-tryptophan ingestion

A 51-year-old woman developed acute febrile illness with respiratory failure following intake of L-tryptophan. An open lung biopsy specimen established the histopathologic nature of the lung lesion as bronchiolitis obliterans organizing pneumonia (BOOP). There was no evidence of other known causes usually associated with BOOP. Her condition improved with corticosteroid therapy. The entity of BOOP now should be added to the growing list of illnesses associated with the use of L-tryptophan.

The amygdaloid complex, corticotropin releasing factor and stress-induced gastric ulcerogenesis in rats

The amygdaloid complex and corticotropin releasing factor (CRF) are both important in stress reactions and we thus evaluated the effects of intra-amygdalar CRF on stress ulceration in rats. Bilateral micro-applications of CRF (0.05, 0.5 or 5.0 micrograms) into the central amygdala (CEA) attenuated cold restraint-induced gastric mucosal lesions in a dose-related manner. Similar gastric cytoprotective effects were seen with intra-CEA noradrenaline (NA; 3.0 micrograms), whereas the NA neurotoxin, DSP-4 (25 micrograms), or the beta-adrenoceptor antagonist, propranolol (1 microgram), aggravated stress ulcer pathology. Intra-CEA pretreatment with DSP-4 or propranolol clearly reversed the ulceroprotective effects of CRF during stress. These results indicate that the CEA is a neural substrate for CRF effects, and CRF-NA interactions in this limbic area are crucial for the regulation of stress ulcerogenesis.

Teaching humanistic behavior: humanities study in the internal medicine residency

Training in humanism is required in internal medicine residency programs, but teaching and evaluating humanism is difficult. Our program integrates the study of humanities into residency training for professional and personal development; betterment of communication skills; and understanding of ethics.

Chromosome 9 anomalies as the primary clonal alteration in a case of squamous cell carcinoma of the epiglottis

We present the cytogenetic characterization of a short-term culture of a primary squamous cell carcinoma of the epiglottis from a 67-year-old male patient who was admitted to this hospital for treatment. This patient had a history of chronic exposure to tobacco and alcohol, environmental carcinogens known to be related to the etiology of the disease. The tumor karyotype showed three distinct clones: 1) cells with chromosome 9 anomalies; 2) cells with chromosome 9 and other clonal structural anomalies involving chromosomes 1, 11, 14, and 17; and 3) cells whose chromosomes were partially or totally pulverized. The anomalies on chromosome 9 were homozygous inversion (p12q13), deletions at regions q22, q34.1, and p13, and i(9q) formation. Structural clonal anomalies on other chromosomes included translocations, deletions, and isochromosome formation. The presence of a chromosome 9 anomaly alone or in conjunction with other anomalies suggests that this aberration may be a nonrandom primary event in the progression of squamous cell carcinoma of the head and neck.

Role of kappa opioid receptors during stress responsiveness in rats

Effects of kappa opioid agonist, ketocyclazocine (KCZ) and its antagonist, M(r) 2266, were evaluated on some stress responses in rats. KCZ (1 or 10 mg/kg, ip) dose-dependently attenuated cold restraint stress (CRS)-induced gastric ulcer formation. Similar gastric cytoprotection was also seen with KCZ (1 or 10 micrograms/rat, icv). Pretreatment of rats with M(r) 2266 (0.3 mg/kg, ip) clearly antagonized the ulceroprotective effects of both ip and icv KCZ. KCZ effects on the gastric mucosa during CRS were also reduced by naltrexone (5 mg/kg, ip) pretreatment. KCZ (1 or 10 mg/kg, ip) also attenuated the plasma corticosterone response to CRS and these effects were blocked by M(r) 2266 (0.3 mg/kg) pretreatment. These results indicate kappa opioid receptor involvement during stress reactions and also suggest possible opioidergic interactions during CRS.

Infections in older patients: a systematic clinical approach

The increased risk of infection among older patients can be divided into three clinical categories: infections increased in incidence, infections showing higher case fatality rates, and infections that are clinically worse, primarily because of late recognition. Among infections that are increased in incidence, the most important by far are tuberculosis and pneumococcal pneumonia. Infections that show higher fatality rates include influenza and--again--pneumococcal pneumonia. Intra-abdominal infections (eg, cholecystitis and appendicitis) are often clinically worse in older patients due to late recognition and delay in surgical intervention.

Effects of Azadirachta indica A Juss on some biochemical, immunological and visceral parameters in normal and stressed rats

Effects of A. indica (AI) were evaluated on some biochemical, immunological and visceral parameters in normal and stress rats. AI (100 mg/kg) lowered blood glucose, triglyceride and SGOT levels in normal rats, and attenuated stress-induced elevations of cholesterol and urea levels. In rats immunized with SRBC, AI enhanced the humoral antibody response to the antigen. Further, AI facilitated the footpad thickness response to SRBC in sensitized mice and also enhanced leucocyte migration in immunized rats. In stressed rats, AI significantly attenuated the stress-induced (a) suppression of humoral immune response and (b) gastric ulcerogenesis. These results are discussed in light of the possible mechanisms involved in the effects of AI in normal and stressful situations.

Central histaminergic involvement during stress in rats

Effects of some drugs modulating central histaminergic (HA) transmission were evaluated on restraint stress (RS)-induced gastric ulcerogenesis, plasma corticosterone and immune responses in rats. RS for (i) 6 hr or (ii) 24 hr at room temperature, and (iii) 3 hr at 4 degrees C (CRS) all induced gastric mucosal erosions and elevated plasma corticosterone levels, the effects with the latter two RS procedures being most consistent. Pretreatment of rats with neuronal HA depletor, alpha-FMH (100 mg/kg, ip) attenuated both ulcer severity and corticosterone response, during both 24 hr RS and CRS. Similar effects were also seen with the mast cell degranulator, C-48/80 (10 micrograms/kg, i.c.v.) treatment. Further, the H1-blocker, pheniramine (25 mg/kg, ip) but not the centrally acting H2-blocker, zolantidine (5 mg/kg, ip) produced clearcut attenuations in both stress markers, during the experimental stressors. In rats immunized in SRBC, 24 hr RS (and not CRS) significantly prevented the humoral immune responses to the antigen. alpha-FMH, C 48/80 and pheniramine but not zolantidine, reversed this response during 24 hr RS. The results indicate a central HA ergic involvement in the visceral, endocrinal and immune responses during RS and suggest the probable role of both neuronal as well as extraneuronal (mast cell) HA and activation of H1-receptors in the mediation of these effects.

Mechanism of anti-stress activity of Ocimum sanctum Linn, eugenol and Tinospora malabarica in experimental animals

Effects of restraint stress (RS) and its modulation by O. sanctum (Os), eugenol and T. malabarica (Tm) were evaluated on some biochemical and biophysical parameters in rats. RS induced elevations in blood glucose and urea levels, were unaffected by either Os, eugenol or Tm pretreatment. However, both Os and eugenol lowered RS-induced cholesterol levels. RS also caused a generalized increase in enzyme activity and Os, eugenol or Tm effectively lowered the RS-induced elevations in lactate dehydrogenase (LDH) and alkaline phosphatase. RS also induced (a) increased membrane protein clusterization, (b) increased membrane fluidity and (c) reduced membrane thickness--in RBC membrane, whereas, the effects on the synaptosomal membrane were less marked. The RS-induced changes in RBC membrane dynamics were attenuated/reversed by Os, eugenol or Tm, in a differential manner. These biochemical and membrane changes during Rs and their modulation by the adaptogens are discussed in light of the possible mechanisms of action of these agents, during such aversive stimuli.

A calcium model with random absorption: a stochastic approach

Absorption of calcium, or any mineral, by the body is subject to the random fluctuations typical of diffusion through membranes. In this paper we consider the absorption of calcium from the gut as a white noise process added to the deterministic model of Sen & Mohr (1990, J. theor. Biol. 142, 179-188). The first two moments for the amount of calcium in the extracellular fluid (ECF) have been derived using the Ito Calculus. A confidence interval for the total amount of calcium in the ECF is constructed. The equations for the first two moments of the fraction of dose calcium in the ECF are also given. Suggestions are made for the collection of experimental data in a form which should be helpful in investigating the magnitude of the stochastic effect.

Modulation by naltrexone of stress-induced changes in humoral immune responsiveness and gastric mucosal integrity in rats

The effects of restraint stress (RS) and the opioid antagonist, naltrexone, were evaluated on humoral immune responsiveness and gastric mucosal integrity in rats. RS for 24 h, but not 6 h, attenuated both the primary (PAR) and secondary antibody response (SAR) to sheep red blood cells (SRBC) after a single exposure to the stressor. Naltrexone (1 or 5 mg/kg) dose-dependently aggravated the effects of RS on anti-SRBC antibody titre in both PAR and SAR studies. Further, in rats sensitized with SRBC, RS (24 h), in addition to lowering the humoral antibody response, also induced gastric mucosal lesions. Both these responses were further aggravated with naltrexone pretreatment. These results are discussed in light of interactions between immune and visceral responses, and their regulation by endogenous opioids, during RS.

Initiation of heroin abuse: the role of peers

A study comprising of detail history collection of first - day heroin chasing of 80 heroin addicts in respect to the contribution of their peers was done. Analysis reveals that the peer group influence was significantly operative in several ways in the initiation of heroin abuse.

Sonographic evaluation of operability of malignant cervical lymph nodes

Infiltration of the carotid artery by malignant cervical nodes is considered to be a contraindication for radical neck dissection in many centers. Clinical examination alone is unlikely to provide information on the fixity of nodes to the carotid artery. We studied the role of ultrasonography as an adjunct to clinical examination in screening patients for neck dissection. Twenty-seven patients with clinical neck node metastasis were chosen for ultrasonography. All of them had surgery and the findings were correlated. The findings revealed that this procedure is effective in delineating involvement of carotid artery by neck nodes and in identifying false-positive and false-negative cases. Since the sample of patients studied was small, the study is continuing in order to accrue a larger sample.

Modulation of humoral immune responses by Tinospora malabarica in experimental animals

Effect of alkaloidal fraction of aqueous extract of T. malabarica (Tm) was studied on humoral antibody responses in rats and guineapigs. The anti-SRBC haemagglutination titre was found to be enhanced in rats pretreated with Tm (2.5 mg/kg). Passive cutaneous anaphylaxis (PCA) in rats was also increased in Tm treated group. In vitro experiments with sensitized rat peritoneal mast cells showed a significant decrease in antigen-induced various spasmogens on isolated guineapig ileum.

Effects of some imidazoles on cellular immune responses--an experimental study

Effects of some imidazole compounds were studied on two animal models of cellular immune responses. Metronidazole in doses of 100 and 200 mg/kg and cimetidine 200mg/kg (ip), significantly suppressed the delayed type of hypersensitivity reaction, as evidenced by the footpad thickness method in mice. No significant alteration in the response could be observed however, in tinidazole treated groups. All the three drugs inhibited the migration of leucocytes in the presence of antigen in rats considerably. However, they did not produce any involution of spleen or reduction of adrenal weight indicating that their actions are not corticosteroid mediated. All the three drugs studied are histamine-like imidazole derivatives. H2 receptors are present on the surface of T-lymphocytes. They appear to modulate the cellular immune response by altering the function of the regulatory lymphocytes.

Role of histaminergic mechanisms in the regulation of some stress responses in rats

The involvement of histaminergic mechanisms in the regulation of some stress responses was studied in rats. The brain neuronal histamine (HA) depletor, alpha-fluoromethyl histidine (alpha-FMH), at doses (50 or 100 mg/kg) which markedly lower brain HA, significantly attenuated the gastric ulcer formation and the elevation in plasma corticosterone in response to cold restraint stress (CRS). alpha-FMH also appreciably reduced gastric mucosal HA content. The H1-antagonist, pheniramine (25 mg/kg), attenuated both the gastric mucosal and endocrine response to CRS, while the effects of the H2-antagonist, cimetidine (200 mg/kg), were on the plasma corticosterone levels. These results are discussed in light of complex HA-ergic mechanisms in the maintenance of physiological homeostasis during stress.

Oral candidiasis as a marker of acute retroviral illness

All reported clinical characteristics of acute retroviral illness with the human immunodeficiency virus (HIV) are nonspecific. Signs and symptoms described are associated with a variety of acute infections. We report the cases of three patients in whom the acute retroviral illness was characterized by transient oral candidiasis and unexplained high lactate dehydrogenase values, with or without transient pulmonary infiltrate, in the context of an acute febrile illness. The clinical findings correlated with a severe reduction in the number of CD4 cells. We believe that thrush could be a marker of acute retroviral infection, as it is not a feature of any other heterophil-negative mononucleosis-like syndrome. We propose that in any patient having transient thrush and acute viral syndrome, the possibility of HIV infection should be aggressively pursued serologically, regardless of the patient's HIV risk status, provided that the usual causes of candidiasis (eg, diabetes mellitus, antibiotic use, and dentures) can be excluded.

Effects of preformed immune complexes on liver enzymes & their serum clearance in mice

Two different performed HSA-anti-HSA immune aggregates, insoluble complex at equivalence (IC-E) and soluble complex with 5 times antigen excess (IC-S)-were administered iv in experimental mice to study their interaction with liver cells. Both complexes produced no appreciable change in the levels of liver enzymes like acid phosphatase, cathepsin D and gamma-glutamyl transferase. However, marked reduction in the level of liver pseduocholinesterase (as much as 93%) was recorded in the treated animals under identical conditions of administration of both the complexes. Hepatic uptake studies revealed that within 5 min, maximal sequestration of IC occurred within the liver (10 to 18%) and the blood (70 to 82%) when computed in terms of total injected radioactive IC. After 4 h, radioactivity dropped to 3 per cent in liver and 50-40 per cent in blood. The liver seemed to be incapable of scavenging all the serum complexes at a time. Significant consumption of serum complement occurred, when freshly prepared complexes were administered to the animals, but the reduced complement level showed a tendency to reach normalcy after 2 h. The soluble and equivalence zone IC failed to exhibit identifiable discrimination facets with respect to handling by liver. The complexes IC-E and IC-S also behaved in a similar manner.

Histaminergic mechanisms in experimental convulsions

Effect of some histamine (HA) agonists and antagonists were assessed on electroshock (MES) convulsions in mice and rats. In mice, pretreatment with the HA precursor, l-histidine (100, 500 and 1000 mg/kg) precipitated seizures after a subthreshold (30 mA) stimulus. Both incidence (%) and tonic hind limb extensor phase (THE) were more than that in vehicle treated controls. The H1 blockers, pheniramine (25 mg/kg) and promethazine (25 mg/kg) both protected against (60 mA) MES and both incidence of convulsions and THE were reduced. A similar protective effect was not seen with either the H2 blocker, cimetidine (up to 200 mg/kg), or atropine (1 mg/kg). In rats, both the classical antihistamines blocked MES seizures, whereas, the H2-blocker, cimetidine, and atropine were, ineffective. Further, both H1 blockers were ineffective in antagonizing seizures induced by pentylenetetrazole, INH, caffeine or strychnine. These results are discussed in light of a possible HA-ergic regulation of experimental convulsions.

Effects of stress on immune responsiveness, gastric ulcerogenesis and plasma corticosterone in rats: modulation by diazepam and naltrexone

Effects of restraint stress (24 hr at room temperature) were evaluated on some immunological, visceral and endocrinal responses in rats. In animals sensitized with sheep RBC (SRBC), restraint stress (a) prevented the booster-induced rise in anti-SRBC antibody titre, (b) induced gastric mucosal erosions, and (c) elevated plasma corticosterone, when compared to non-stressed controls. Diazepam (1 or 10 mg/kg) consistently attenuated the effects of stress on all three parameters studied. The opioid antagonist, naltrexone (1 or 5 mg/kg) tended to aggravate these stress-induced effects. These concurrent biological changes during stress and their modulation by drugs are discussed in light of a possible correlation between endocrinal, immunological and visceral changes during such aversive stimuli.

Possible prostaglandin-dopamine interactions during experimental gastric ulcer formation

The effects of dopamine (DA) agonists and antagonists were investigated on indomethacin--and restraint stress (6 hr at RT)--induced gastric ulcer formation in rats. The DA-agonists, apomorphine and bromocryptine (both at 5 mg/kg) significantly attenuated the frequency and severity of gastric mucosal lesions in both experimental models. The DA-antagonist, haloperidol (0.05 and 1.0 mg/kg) aggravated the gastric ulcerogenesis of both indomethacin and stress, the effects with the lower dose being statistically significant. Haloperidol (0.05 mg/kg) also prevented the cytoprotective effects of apomorphine on indomethacin-ulcers. The atypical DA-antagonist, sulpiride (10 and 50 mg/kg), however, showed differential dose- and model-specific effects. Whereas, the lower dose attenuated indomethacin-ulcers, the higher dose (50 mg/kg) tended to aggravate this phenomenon. The trend of results were reversed in the restraint stress model. Indomethacin (1 mg/kg) aggravated stress-ulcers, an effect which was also appreciably neutralised by apomorphine (5 mg/kg) pretreatment. These results are discussed in light of possible prostaglandin-DA interactions during such experimental gastric pathology.

Induction of chromosome breaks and sister chromatid exchanges in patients with Hodgkin's disease by two combination chemotherapy regimens of different leukemogenic potential

The success of various combination chemotherapies in the treatment of cancer is compromised by their potential to cause secondary leukemia. Previous studies have suggested that the alkylating agents used in some regimens are the major etiological factor in these leukemias. In this study, we compared the abilities of two standard regimens used in the treatment of Hodgkin's disease to cause chromosome breaks and sister chromatid exchanges, the two most common types of chromosomal damage induced by alkylating agents. These regimens are MOPP [mechlorethamine-vincristine (Oncovin)-procarbazine-prednisone] and CVPP-ABDIC [cyclophosphamide-vinblastine-procarbazine-prednisone-doxorubicin (Adriamycin)-bleomycin-dacarbazine-1-(2-chloroethyl)-3-cyclohexyl-1- nitrosourea]. Our study demonstrated that (a) levels of spontaneous chromosome breaks and sister chromatid exchanges were low in untreated Hodgkin's disease patients; (b) significantly higher levels of these damages were induced in patients receiving eight cycles of CVPP-ABDIC, as compared with their pretreatment levels; (c) significantly elevated levels of sister chromatid exchanges, but not chromosome breaks, were induced in patients receiving two cycles of MOPP; and (d) no differences in the effect of these two regimens on cell cycle kinetics were observed. Although MOPP therapy has been reported to have higher rates of secondary leukemia than CVPP-ABDIC, our studies show that eight cycles of CVPP-ABDIC are more potent than two cycles of MOPP in inducing chromosome damage in patients during treatments.

A kinetic model for calcium distribution

Models for the distribution of minerals in the body are of interest as they allow researchers to trace the effect of a dose on mineral levels in plasma, storage and other compartments. Limited models are available in the literature for tracing the distribution of a calcium dose through a short time period. We propose a more general kinetic model which includes both limited absorption through the gut and loss of calcium via excretion. This new method has the advantages of giving reasonable results over moderate time periods, and allowing the extrapolation of calcium levels in extracellular fluid and storage. We fit the model to published data in order to obtain typical parameter values. These values are then used to analyze the implications of the model regarding the effect of calcium dose on calcium levels in various compartments.