Spinal anesthesia for cesarean section: isobaric versus hyperbaric solution

BACKGROUND

The present study was undertaken to compare the outcomes of hyperbaric versus isobaric spinal anesthesia in Cesarean delivery.

METHODS

The anesthetic solution was administered in sitting position as this posture is commonly used in this clinical setting. Except for the baricity of the anesthetic solution, identical technique was employed for every parturient in the study. Following administration of anesthetic solution the parturient immediately resumed horizontal supine position. The solutions used were 2.0 mL of 0.5% tetracaine in 5% dextrose (hyperbaric) for Group H (n = 30) and in cerebrospinal fluid (isobaric) for Group I (n = 30).

RESULTS

Both hyperbaric and isobaric tetracaine given in sitting position provided adequate analgesic levels. However, hyperbaric tetracaine solution produced a slightly higher median peak level of wilder range, and caused a higher incidence of hemodynamic changes and subjective sensation of "feeling sick" than isobaric tetracaine. Additionally, the duration of surgical anesthesia was shorter and the sacral block was longer for hyperbaric tetracaine solution than for isobaric tetracaine solution at same dose and concentration. Only one mother in Group H needed supplemental inhalation anesthesia for a subsequent hysterectomy due to uncontrollable bleeding. There were no complications, including postpuncture headache in either group.

CONCLUSIONS

Our results indicated that numerous variables must be taken into consideration in predicting the outcome of a spinal anesthesia. Alternation in the technique and individual patient factor may individually or collectively produce different results.

Elevated plasma levels of F2 alpha isoprostane in cystic fibrosis

Cystic fibrosis (CF) is associated with chronic lung infection, inflammation, and elevated indices of oxidative stress. Recently, isoprostanes were shown to be a reliable in vivo marker of oxidant injury with 8-iso-PGF2 alpha, shown to cause airflow obstruction and plasma exudation in guinea pig lung. The present study was designed to examine the relationship between 8-iso-PGF2 alpha levels, plasma antioxidants, and clinical status in CF. We hypothesized that plasma 8-iso-PGF2 alpha levels would be higher in subjects with CF compared to healthy controls. Plasma 8-iso-PGF2 alpha levels were prospectively measured in 22 subjects with CF and nine healthy controls using an 8-isoprostane enzyme immunoassay kit along with plasma vitamins A, E, and beta-carotene. Plasma 8-iso-PGF2 alpha levels were shown to be significantly elevated in the CF subjects compared to controls (319.6 +/- 52.6 vs. 145.0 +/- 21.0 pg/mL, P = 0.005). Plasma levels of antioxidants were significantly lower for the CF subjects compared to the controls (vitamin A, P < 0.003; vitamin E, P < 0.001; and beta-carotene, P < 0.01). This study confirms significantly elevated lipid peroxidation in CF using 8-iso-PGF2 alpha levels.

Approaches to managing carboplatin-induced thrombocytopenia: focus on the role of amifostine

Thrombocytopenia is a significant problem for patients receiving prolonged or aggressive chemotherapy for malignancy. For carboplatin, it is the predominant dose-limiting toxicity and it is cumulative in nature. A number of agents have been evaluated for efficacy in reducing the problem of thrombocytopenia. Some have proved valueless and have been discarded. Others (eg, recombinant thrombopoietin) are under current study, and one (interleukin-11 or oprelvekin) is now commercially available. In addition, the currently available cytoprotectant, amifostine (Ethyol; Alza Pharmaceuticals, Palo Alto, CA/US Bioscience, West Conshohocken, PA), has been shown to reduce the severity and duration of thrombocytopenia caused by carboplatin. Because of the short half-life of amifostine relative to that of carboplatin, multiple doses of amifostine have been administered in conjunction with carboplatin. The optimal dosing regimen with amifostine and carboplatin needs to be further evaluated in clinical studies. Future trials will also expand these observations to carboplatin-containing combination chemotherapy regimens and will further define the role of amifostine as a multilineage bone marrow protectant. The ability of amifostine to demonstrate multilineage bone marrow protection differentiates it from currently available growth factors and fulfills a medical need, including reducing the need for platelet transfusions and maintaining the desired chemotherapy dose intensity.

Isobaric spinal anesthesia for paraplegic patients

It has long been understood that patients with spinal cord injury (SCI) above T6-7 may develop autonomic hyperreflexia (AH) and pose an anesthetic challenge. To date, there is no consensus regarding anesthesia management of these patients among anesthesiologists. Many anesthetic techniques have been proposed and used with varying success, but none of them is uniformly successful. Topical anesthetics may not block the stretch receptors and AH might still be initiated. A deep anesthesia with potent volatile agents is often necessary to prevent or treat AH. Thus, the incidence of hypotension is no different than that associated with neuraxial anesthesia. Failures with potent vasodilators such as sodium nitroprusside also have been reported. Currently, the block of the afferent pathways by neuraxial anesthesia is considered to be the most effective means of preventing AH. However, because the level of neuraxial anesthesia is difficult to detect in SCI patients, excessive high level block and subsequent severe hypotension may occur. When an isobaric solution is used, due to the lack of baricity/patient position interaction, migration of the local anesthetic is usually insignificant, so the level of anesthesia is easier to control and predict. In the past fifteen years (1982-1997), we have used isobaric spinal anesthesia (ISA) in thirteen patients with SCI for various surgical procedures. Although four of these patients had previous history of AH, there was not a single incidence of AH during the perioperative period. Our favorable experiences lead us to believe that ISA is a useful anesthetic technique for SCI patients undergoing surgery.

The medical dictionary for regulatory activities (MedDRA)

The International Conference on Harmonisation has agreed upon the structure and content of the Medical Dictionary for Regulatory Activities (MedDRA) version 2.0 which should become available in the early part of 1999. This medical terminology is intended for use in the pre- and postmarketing phases of the medicines regulatory process, covering diagnoses, symptoms and signs, adverse drug reactions and therapeutic indications, the names and qualitative results of investigations, surgical and medical procedures, and medical/social history. It can be used for recording adverse events and medical history in clinical trials, in the analysis and tabulations of data from these trials and in the expedited submission of safety data to government regulatory authorities, as well as in constructing standard product information and documentation for applications for marketing authorisation. After licensing of a medicine, it may be used in pharmacovigilance and is expected to be the preferred terminology for international electronic regulatory communication. MedDRA is a hierarchical terminology with 5 levels and is multiaxial: terms may exist in more than 1 vertical axis, providing specificity of terms for data entry and flexibility in data retrieval. Terms in MedDRA were derived from several sources including the WHO's adverse reaction terminology (WHO-ART), Coding Symbols for a Thesaurus of Adverse Reaction Terms (COSTART), International Classification of Diseases (ICD) 9 and ICD9-CM. It will be maintained, further developed and distributed by a Maintenance Support Services Organisation (MSSO). It is anticipated that using MedDRA will improve the quality of data captured on databases, support effective analysis by providing clinically relevant groupings of terms and facilitate electronic communication of data, although as a new tool, users will need to invest time in gaining expertise in its use.

Regulation of IL-5 and IL-5 receptor expression in the bone marrow of allergic asthmatics

BACKGROUND

Following consistent demonstrations of the clinical relevance of fluctuations in eosinophil-basophil (Eo-B) progenitors in the blood of patients with a variety of allergic airway disorders, we have turned our attention recently to hemopoietic events occurring in the bone marrow of allergic asthmatic subjects, utilizing a model of airway allergen challenge.

METHODS

Flow-cytometric analyses of CD34/45+ progenitors for coexpression of surface alpha-receptor subunits for IL-3, IL-5 and GM-CSF, as well as in situ hybridization and in situ PCR methodologies to detect mRNA for IL-5 and GM-CSF in developing Eo-B in colony and liquid culture assays were employed before and after in vivo allergen challenge.

RESULTS

An early, specific upregulation of IL-5R alpha expression on CD34/45 progenitors was observed after allergen challenge, concomitant with the development of the late-phase asthmatic response. Protein and mRNA for both GM-CSF and IL-5 were expressed in a time-dependent manner ex vivo, in developing (beta 7-integrin-positive), colony-derived Eo-B after allergen challenge in vivo. Both retinoic acid and corticosteroids were able to downregulate IL-3- and IL-5-induced expression of IL-5R on cord-blood-derived as well as HL-60 cloned Eo-B progenitors.

CONCLUSION

These studies indicate the critical involvement of IL-5 and IL-5R in the induction of Eo-B differentiation and eosinophilic airway inflammation in allergic asthmatics, and point to these events as potential targets for long-term therapy of atopic disease.

Demonstration of delayed recovery from fatiguing exercise in chronic fatigue syndrome

Patients with the chronic fatigue syndrome (CFS) complain consistently of delay in recovery of peripheral muscle function after exercise. The purpose of this study was to try to confirm this observation. A fatiguing exercise test was carried out on the quadriceps muscle group of ten patients and ten control subjects. The test consisted of 18 maximum voluntary contractions (MVCs) with a 50% duty cycle (10 s contraction, 10 s rest), and the force generated by each contraction was recorded using a KinCom dynamometer. This was followed by a recovery phase lasting 200 min in which quadriceps strength was evaluated at increasing intervals, and a follow-up session at 24 h post-exercise involving three 10 s MVCs. Throughout the exercise period, the MVCs obtained from the control group were significantly higher than those of the patient group (P = 0.006), but both groups showed a parallel decline in force over the 18 contractions, in keeping with a similar endurance capacity. Recovery was prolonged in the patient group, however, with a significant difference compared to initial MVCs being evident during the recovery phase after exercise (P = 0.001) and also at 24 h (P < 0.001). In contrast, the control group achieved MVCs which were not significantly different from initial values during the recovery phase, and maintained these at 24 h. These findings support the clinical complaint of delayed recovery after exercise in patients with CFS.

2'-Chlorodeoxyadenosine Effectively Induces Complete Remission in Hairy Cell Leukaemia

Hairy cell leukaemia, previously known as leukaemic reticuloendotheliosis, is an indolent lymphoproliferative disorder of unknown etiology. It typically affects males, causes marked splenomegaly and moderate enlargement of the liver, whilst lymphadenopathy is inconspicuous. Pancytopenia is characteristic with unusually profound monocytopenia, variable reduction in platelets, and the presence in the peripheral blood and marrow of abnormal small lymphocytes having irregular cytoplasmic margins. Ultrastructure, combined with cytochemistry and flow cytometry, have refined diagnosis. A variant exists between this classical entity and B prolymphocytic leukaemia, where blastic transformation or massive lymph node enlargement are found, and this is of ominous significance. In all these patients with this entity conventional chemotherapy is ineffective and shortens survival. Our previous experience with splenectomy results in excellent clinical control for long periods of time, but without disease eradication. There followed a vogue for the use of interferon but this is limited by high cost and dose-dependent side-effects. Contemporary management centres on the purine analogues, where durable responses are possible with fludarabine and deoxycoformycin, but best with 2'chlorodeoxyadenosine (2-CDA). To document the efficacy of the latter agent, we analysed the outcome in seventeen consecutive patients treated over the last five years. Four were ineligible for analysis, although two had 2-CDA. The other thirteen, managed on a standard seven-day course of 0.1 mg/kg 2-CDA given as a continuous intravenous infusion, all responded promptly. Apart from transient leucopenia complications have been minimal, and oral co-trimoxazole prophylaxis for pneumocystis carinii was maintained during the first one year. In all thirteen there was a rapid return to normal of peripheral blood count and marrow on aspiration and trephine biopsy. Even in the longest follow-up clinical and haematologic remission has been maintained and no patients have required retreatment. One individual has relapsed in the marrow at two years. Despite the relative expense of the agent the excellent treatment outcome and patient acceptability, coupled with its safety, leads to the recommendation that in South Africa-as elsewhere in the world-this be regarded as the first line of treatment.

Oral immunization with enterocoated microbeads induces antigen-specific cytolytic T-cell responses

A cytolytic T-lymphocyte (CTL) response has been generated to a protein antigen via oral administration in an experimental murine system. This was achieved by the formulation of the test antigen ovalbumin (OVA) in a pH-sensitive microsphere particle (microbead) with an acrylic-based coating to avoid its degradation by gastric enzymes. Comparative studies of orally administered enterocoated microbead-OVA particles, versus the more traditional formulation of OVA in adjuvant (DETOX-PC) given subcutaneously as immunogen, were conducted; both elicited comparable responses in the generation of antigen-specific lymphoproliferative and CTL responses. CTL lines generated via oral administration of antigen were shown to be CD3(+), CD4(-), and CD8(+). CTL lysis of OVA peptide-pulsed targets was shown to be inhibited by anti-CD8 antibody. Whereas oral administration of pH-sensitive enterocoated microbeads containing proteins has previously been shown to elicit antibody and lymphoproliferative T-cell responses to protein antigens, this is the first demonstration of the generation of an antigen-specific cytolytic T-cell response via oral administration of a protein immunogen formulated in such microbeads.

Bone marrow contribution to eosinophilic inflammation

Allergen-induced bone marrow responses are observable in human allergic asthmatics, involving specific increases in eosinophil-basophil progenitors (Eo/B-CFU), measured either by hemopoietic assays or by flow cytometric analyses of CD34-positive, IL-3R alpha-positive, and/or IL-5-responsive cell populations. The results are consistent with the upregulation of an IL-5-sensitive population of progenitors in allergen-induced late phase asthmatic responses. Studies in vitro on the phenotype of developing eosinophils and basophils suggest that the early acquisition of IL-5R alpha, as well as the capacity to produce cytokines such as GM-CSF and IL-5, are features of the differentiation process. These observations are consistent with findings in animal models, indicating that allergen-induced increases in bone marrow progenitor formation depend on hemopoietic factor(s) released post-allergen. The possibility that there is constitutive marrow upregulation of eosinophilopoiesis in allergic airways disease is also an area for future investigation.

Structure-function studies of ligand-induced epidermal growth factor receptor dimerization

We present a novel 96-well assay which we have applied to a structure-function study of epidermal growth factor receptor dimerization. The basis of the assay lies in the increased probability of EGFRs being captured as dimers by a bivalent antibody when they are immobilized in the presence of a cognate ligand. Once immobilized, the antibody acts as a tether, retaining the receptor in its dimeric state with a resultant 5-7-fold increase in binding of a radiolabeled ligand probe. When the assay was applied to members of the EGF ligand family, murine EGF, transforming growth factor alpha, and heparin-binding EGF-like growth factor were comparable with human EGF (EC50 = 2nM); betacellulin, which has a broader receptor specificity, was slightly less effective. In contrast, amphiregulin (AR1-84), which has a truncated C-tail and lacks a conserved leucine residue, was ineffective unless used at >1 microM. We further probed the involvement of the C-tail and the conserved leucine residue in receptor dimerization by comparing the activities of two genetically modified EGFs (the chimera mEGF/TGFalpha44-50 and the EGF point mutant L47A) and a C-terminally extended form of AR (AR1-90) with those of two other unrelated EGF mutants (I23T and L15A). The potency of these ligands was in the order EGF > I23T > mEGF/TGFalpha44-50 > L47A = L15A >> AR1-90 > AR1-84. Although AR was much worse than predicted from its affinity, this defect could be partially rectified by co-localization of the immobilizing antibody with heparin. Thus, it seems likely that AR cannot dimerize the EGFR unless other accessory molecules are present to stabilize its functional association with the EGFR.

The effects of skin brushing on H reflex amplitude in normal human subjects

Experiments were performed on twenty-two neurologically normal subjects in order to investigate the effects of skin brushing on H reflex excitability in triceps surae. H reflex amplitude was observed to decrease during brushing of a 2 cm x 10 cm area of skin overlying triceps surae, returning to control levels when brushing ceased. Alterations in the duration of the brushing period did not affect the magnitude of the H reflex inhibition, although increased frequency of brush strokes per minute slightly increased the amount of inhibition observed. Brushing of smaller skin areas overlying the muscle only sometimes resulted in H reflex inhibition. Brushing over other skin areas of the lower limb produced only slight effects on triceps surae H reflex amplitude. Removal of cutaneous input from the skin overlying triceps surae abolished any effects of brushing in this area on H reflex amplitude. These results demonstrate an inhibitory effect of brushing on H reflex excitability in normal subjects. If such results are confirmed in subjects with neurological deficit, they could have implications for the use of brushing in clinical practice.

Intra-specific variation in the photosynthetic responses of cyanobiont lichens from contrasting habitats

The photosynthetic properties of cyanobiont lichens from contrasting habitats were measured to identify whether the increased assimilation rates which characterized Peltigera membranacea (Ach.) Nyl. from an exposed habitat were correlated with increased carbon-concentrating mechanism (CCM) activity. The results were contrasted with data obtained from two populations of Peltigera praetextata (Flörke ex Sommerf.) Zopf collected from dry and damp microhabitats within a shaded woodland and Peltigera leucophlebia (Nyl.) Gyelnik, which has been shown to lack a carbon-concentrating mechanism. The differences in assimilation rates between the cyanobiont lichens were not accounted for by differences in chlorophyll content. Peltigera membranacea from the exposed habitat which had the highest assimilation rates had the lowest Gamma; and K_0·5 values and accumulated the greatest C_i -pool indicating that increased C_i accumulation contributed towards the higher assimilation rates shown by these species. The convexity of the light response curve for the cyanobiont lichens decreased with increasing assimilation rates. This might have indicated a diversion of electron transport to energize the carbon-concentrating mechanism. The apparent quantum efficiency of CO₂ assimilation (ΦCO₂ ) was correlated with the genus of lichen photobiont. All cyanobiont lichens had comparable values for ΦCO₂ which were greater than that of the tripartite Peltigera leucophlebia. Light compensation points reflected the exposure of the habitats with higher compensation points characterizing the cyanobiont population from the exposed crag and the tri-partite population from the open grassland. Carbon isotope discrimination values for organic matter and measured instantaneously were the same for all cyanobiont lichens and were comparable with values recorded for species with a carbon-concentrating mechanism. Carbon isotope measurements for P. leucophlebia were typical of those recorded for species without a carbon-concentrating mechanism. Variation in source isotope signature and refixation of respiratory CO₂ were considered to be significant factors in determining organic matter and instantaneous carbon-isotope discrimination. These factors might have masked any subtle variation in carbon-isotope discrimination which resulted from variable CCM activity. The functional significance of increased carbon-concentrating mechanism activity in cyanobiont lichens occupying exposed habitats is discussed.

Results of a phase III, double-blind, placebo-controlled trial of megestrol acetate modulation of P-glycoprotein-mediated drug resistance in the first-line management of small-cell lung carcinoma

The objective of this study was to determine if the addition of megestrol acetate (MA), a modulator of P-glycoprotein-mediated drug resistance, to first-line cytotoxic therapy in patients with limited and advanced stage small-cell lung cancer (SCLC) would improve median time to disease progression and median overall survival. Secondary outcomes evaluated were response rates and patient symptom profile. Between 1992 and 1995, 130 eligible patients were randomized in a double-blind fashion to receive standard first-line therapy consisting of alternating courses of cyclophosphamide/doxorubicin/vincristine and etoposide/cisplatin (and thoracic radiotherapy for limited stage patients), along with either placebo or MA 160 mg t.i.d. for 8 days commencing 3 days before initiation of each cycle of chemotherapy. Treatment was continued for a maximum of six cycles. A total of 130 eligible patients were randomized, 65 to each arm. Fifty-two per cent of patients had limited disease and 48% had advanced disease. The median time to disease progression in limited stage disease was 46 weeks in the placebo arm and 43 weeks in the MA arm (P = 0.71) and in advanced stage disease was 28 weeks in the placebo arm and 27 weeks in the MA arm (P = 0.92). The median overall survival in limited stage disease was 75 weeks in the placebo arm and 75 weeks in the MA arm (P = 0.56) and in advanced stage disease was 41 weeks in the placebo arm and 39 weeks in the MA arm (P = 0.96). There was no consistent statistical difference in response rates or patient symptom profiles between the two treatment arms. The addition of MA, in the dose and schedule used, to standard first-line cytotoxic therapy in SCLC did not result in a significant improvement in response rates, symptom profile, median time to disease progression or overall survival.

Cost Effectiveness of G:CSF in Chemotherapy and Transplant-related Neutropenia

Sustained fever over 38°C is potentially lethal when neutrophil counts remain below 0.1 × 10(9)/L. To determine whether the addition of a haematopoietic stimulatory peptide to conventional supportive care and antibiotic management was cost-effective, 74 such episodes were analysed. Group I (5μg/kg G: CSF: n = 41); Group II (10 μg/kg: n = 19) and Group III (controls: n = 14): these were similar in respect of race, gender, age and body weight. The median days and range of neutrophil count below 0.1 × 10(9)/Lw as 6 (0-12), 7 (0-20) and 8 (0-20) and the corresponding figures for 0.5 × 10(9)/L were 8 (0-19), 8 (1-23) and 13.5 (3-30) days respectively, while the median hospital period was 26 (18-49), 30 (9-86) and 35 (13-44). Mean, standard deviation and range for bed costs in Group I was R9,528 (2125:6120-1660), the corresponding figures for Group II were Rll,453 (5570:3060-2924), and for Group III Rll,366 (2755: 4420-1496). The approximate fate of exchange is: Rl = US$5.87. When expenditure for growth factor was integrated these figures were approximately R26,071, R37,787 and R27,376. There were no advantages in 10 over 5 μg/kg G: CSF. More red cell transfusions were needed in Group III. The days requiring antimicrobial therapy were 14, 16 and 20 respectively. It is concluded from this study, carried out in reverse isolation at a University Teaching Hospital, that duration of neutropenic fever was significantly shortened on G: CSF but there was no benefit in using the higher dose. Additionally, at equivalent cost, there was a shorter period of hospitalisation thereby reducing risk of acquiring nosocomial infections. Finally, there was concurrently a decreased exposure to potentially nephrotoxic antibiotics. Accordingly, this regimen can be justified in the routine management of this category of patient.

Refractory Castleman's Disease

Angiofollicular lymph node hyperplasia is an uncommon low-grade lymphoproliferative disorder first described by Castleman. It is typically asymptomatic with diagnosis incidentally made in young males on chest radiology. Biopsy, in 90% of cases, shows the hyaline vascular variant. In contrast the plasma cell sub-type is accompanied by fever, sweating, weight loss, anaemia, lymphadenopathy, splenomegaly and hypergammaglobulinaemia. Treatment, when necessary because of symptoms, has variable outcome in response to corticosteroids, combinations of cytotoxic drugs, or radiotherapy. Failure to promptly achieve disease control has ominous significance and most patients die. High-dose chemoradiotherapy with bone marrow salvage, using haematopoietic stem and progenitor cells derived from bone marrow or peripheral blood, has precedent in this situation. We report a second successful outcome to this procedure in a 37 year old man with profound constitutional complaints of weight loss, drenching sweats, relentless high fevers and massive organomegaly, resistant to all previous therapy. After conditioning with total body irradiation, cyclophosphamide and high-dose melphalan followed by total nodal irradiation, he underwent peripheral blood stem cell allograft from an HLA-compatible sister. Despite his course being complicated by pulmonary tuberculosis he achieved immediate complete remission, and restaging at one year confirms this to be durable. This further anecdotal case report supports this option in refractory aggressive variants of this disease.

Myeloma Presenting with Massive Splenomegaly

Myeloma typically presents with skeletal damage, renal failure, metabolic disturbances and anaemia. Less usual associations are polyneuropathy, solitary plasmacytomas, and only rarely is lymphadenopathy found. Discomfort and left upper quadrant pain due to marked splenomegaly appears unknown, particularly as the initial symptom. Accordingly, two cases are reported in which this was the reason for seeking medical attention. In both splenectomy was unavoidable because of size and symptomatic infarction. The dominant histologic feature in the first was striking proliferation of sinus lining cells engorged with the IgA paraprotein. In the second there was dramatic expansion of the red pulp. In neither, despite using appropriate immunohistochemical techniques, could the enlargement of the spleen be attributed to infiltration by plasma cells that in the peripheral and blood and marrow had a distinctively unusual morphology. In these two individuals the pathophysiology remains obscure. In the first, although considered, it was not possible to meet the criteria for this being an example of littoral cell angioma. In the second, a postulated disseminated plasmacytoma with primary splenic sequestration remains unproven. This unique finding is, therefore, presented as descriptive pathology without recognisable explanation.