A Multistate Model for the Fluorescence Response of R-Phycoerythrin

Although strong fluorescence makes the R-phycoerythrin (R-PE) proteins increasingly useful in biological and clinical assays, they are subject to nonlinear effects including transitions to collective dark states and photodegradation, which complicate quantitative applications. We report measurements of R-PE fluorescence intensity as a function of incident power, duration of illumination and temperature. Emission intensity in the band at 570 nm is proportional to incident power for low power levels. At higher incident power, the emission at 570 nm is smaller than expected from a linear dependence on power. We propose that R-PE undergoes both reversible emission cessation on a millisecond time scale attributed to transitions to a collective dark state, and irreversible photodegradation on a time scale of minutes. Singlet oxygen scavengers such as dithiothreitol and n-propyl gallate have protective effects against the latter effect but not the former. Electrophoretic analysis of irradiated solutions of R-PE indicates that significant noncovalent aggregation is correlated with photodegradation. A multistate model based on fluorescence measurements and geometric analysis is proposed for the fluorophores in R-PE. The phycobilin fluorophores are partitioned into three groups: the phycourobilins (PUB) absorbing at 490 nm, one group of phycoerythobilins (PEB) absorbing at 530 nm (PEB-530) and another group of PEB absorbing at 560 nm (PEB-560). The two processes that result in the loss of fluorescence intensity are most likely associated with the PEB-560 group.

Isolation of pathogenic Legionella species and legionella-laden amoebae in dental unit waterlines

Legionella released into the air during treatment are a potential source of infection. Water stagnation in dental unit waterlines (DUWLs) creates biofilms and promotes the proliferation of these micro-organisms. This study investigated the presence of amoeba infected with legionella, L. pneumophila and other pathogenic Legionella species in a dental teaching hospital. Water samples were collected in the morning and afternoon from 99 dental units and 16 taps connected to the municipal water supply. Samples were plated on selective media and tested for legionella using the direct immunofluorescent antibody technique and the latex agglutination test. Legionella were found in 33% of the DUWLs and in 47% of the mains taps supplying these units. Legionella-laden amoebae occurred in one mains tap sample and in 20% of DUWLs in a clinic of the teaching hospital. L. micdadei was the predominant species isolated from this clinic. L. pneumophila serogroups 2-14 predominated in the mains water, whereas L. pneumophila serogroup 1 was found in approximately half of the contaminated DUWLs and mains taps irrespective of the time of sampling. Pathogenic Legionella species seeded by municipal water into DUWLs is a potential source of legionella infection for both dental personnel and patients during prolonged dental treatment. This problem is compounded by the presence of legionella-laden amoebae which may contain levels of organism well within the infective dose. The interaction of legionella with amoebae is an important ecological factor that may significantly increase the risk of legionellosis, and thus should be given further consideration in the refinement of risk assessment models.

Oral versus high dose parenteral iron supplementation in pregnancy

OBJECTIVE

To compare the effect of daily oral iron supplementation with two injections of high dose parenteral iron.

METHOD

A total of 220 pregnant women with a singleton pregnancy and hemoglobin between 8 to 11 g% at 16-24 weeks gestation were identified and randomly divided into two groups. Group A was started on daily oral iron therapy of 100 mg of elemental iron. Group B was given 250 mg of iron sorbitol intramuscularly and repeated at an interval of 4-6 weeks. Blood indices were evaluated at the beginning of study and at 36 weeks to see the effect after iron supplementation in the two groups. The data were analyzed using SPSS software, version 10.1.

RESULTS

Definitive and comparable improvement in hemoglobin and all the blood indices (hematocrit, MCH, MCHC, MCV, Serum iron and TIBC) was observed. The absolute change in hemoglobin and hematocrit was 1.18+/-0.68 g% and 4.02+/-2.59% in oral group, 1.34+/-0.77 g% and 4.93+/-3.65% in parenteral group, respectively. Serum ferritin showed statistically significant absolute rise (10.43+/-7.92 microg/dl) after parenteral iron supplementation as compared to oral iron supplementation (9.76+/-4.78 microg/dl). Obstetric outcome was comparable in two groups.

CONCLUSION

Two treatment regimens are biologically equivalent in terms of hematological response. Two high doses of intramuscular iron can be a good substitute to meet iron requirement in pregnancy.

Spontaneous common bile duct rupture in pregnancy

This report describes how a rare condition in pregnancy can present with features resembling more common diagnoses in the unwell obstetric patient. Our patient presented in late pregnancy initially with clinical features similar to mild preeclampsia, with proteinuric hypertension, epigastric pain and mildly deranged liver function tests. She went on to develop signs of acute abdomen associated with a persistent tachycardia and hypotension; there was evidence of fetal compromise. Following resuscitation, emergency caesarean section was performed and evolved into a laparotomy. The diagnosis was not clear clinically at this stage, but a retrospective amylase sample suggested acute pancreatitis. There was no clinical evidence of biliary perforation, but ongoing clinical suspicion prompted a CT of the abdomen. This proved unhelpful and our diagnostic dilemma was only resolved by endoscopic retrograde cholangiopancreatography, which demonstrated a biliary leak. A stent was placed with subsequent improvement in the patient's condition. With anaesthetists increasingly involved in the multi-disciplinary management of acutely sick obstetric patients, our case highlights the need for every practitioner involved in such cases to assess each individual fully, and be constantly aware that the diagnosis might not be obvious.

Cardiovascular response in anemia

OBJECTIVE

To study the functional consequences of nutritional anemia by evaluating the exercise performance in these children.

METHODS

The study was conducted on 30 each of anemic and normal children of both sexes aged between 7 and 14 years. Relevant history was taken, and detailed examination was done. These children were classified according to severity of anemia based on hemoglobin estimation as mild (10-11.9 g/dl), moderate (7-9.9 g/dl) and normal (>12 g/dl). Children with severe anemia (Hb < 7g/dl), heart disease, non-nutritional anemia, acute febrile or respiratory illness were excluded. The subjects were tested on Mortara X Scribe colour stress treadmill using the modified Bruce protocol. Continuous computerised electrocardiographic analysis was done. The parameters studied included heart rate, systolic blood pressure, double product (DP = HRxSBP), ECG changes, metabolic equivalents (METS) and exercise duration. The end point of the test was a HR of 170/min (non-fatigue group) or inability to perform further (fatigue group). Statistical analysis was done by appropriate tests.

RESULTS

Fifteen children each with mild and moderate anemia and 30 age-matched controls were enrolled in the study. There was no significant difference in the resting HR, exercise duration or DP between the cases and controls. Thirty-one children reached the target HR (non-fatigue group). The end-point HR was significantly lesser among the anemic children in the fatigue group (P 0.04). The percent gain of SBP, at peak exercise (P 0.0007) and recovery SBP as percent of resting SBP (p 0.006) were significantly more in the anemic children, more so in the mildly anemic ones. Lesser METS was achieved by anemics as compared to controls (P 0.04). ECG changes occurred significantly more often in anemic children, 53.8% of those with changes being moderately anemic, the main abnormality being ST depression. None developed arrhythmia during exercise testing.

CONCLUSION

The cardiovascular response to physical exercise is compromised in children with nutritional anemia and hence these children may never attain their full potential in various school activities. Prevention of anemia should be a priority in school going children.

Haematological effect of iron supplementation in breast fed term low birth weight infants

AIMS

To determine the haematological effects of iron supplementation in predominantly breast fed term low birth weight (LBW) infants.

METHODS

Seventy three healthy term LBW (<2500 g), predominantly breast fed infants aged 50-80 days were randomised into two groups to receive either iron (3 mg/kg/day) (iron supplemented (IS) group; n = 37) or placebo drops (placebo (P) group; n = 36). Haematological parameters and anthropometry were measured at baseline and repeated after four and eight weeks.

RESULTS

A total of 62 subjects (32 in the IS group and 30 in the P group) came for the first follow up and 26 (13 in the IS group and 13 in the P group) reported for the second visit. There were no significant differences in serum ferritin and anthropometry. However, covariates (infant age, haemoglobin, and ferritin, and maternal haemoglobin) adjusted haemoglobin change was significantly higher in the IS group after four weeks (4.6 g/l; 95% CI 0.5 to 8.8) and eight weeks (8.6 g/l; 95% CI 1.8 to 15.4).

CONCLUSIONS

Iron supplementation in a therapeutic dose in term breast fed LBW infants results in a marginal increase in haemoglobin. The functional benefit of this haemoglobin rise requires further evaluation.

Gelatinous transformation of bone marrow: a study of 43 cases

Gelatinous marrow transformation (GMT) is an uncommon and poorly recognized condition characterized by deposition of seromucinous gelatinous material in the bone marrow stroma. Forty-three cases of GMT were studied in a period of 4 years. There was male preponderance. Fourteen cases were in pediatric age group (less than 12 years). Majority of patients had a preceding history of anorexia, malnutrition and chronic debility. All the patients had anemia. Bone marrow biopsy revealed focal or diffuse GMT. Bone marrow aspirate showed metachromatic dense mucoid material with a few entrapped hematopoietic cells on Giemsa staining. The gelatinous material stained with alcian blue at pH 2.5.

Gastric mucosal fibrosis: a novel explanation for dyspepsia

The etiology of functional dyspepsia has not been discerned yet which has led to inadequate treatment of this disease. It remains a common disorder with expensive and yet often ineffective therapy. We propose that the pathogenesis of this disease lies in the histological and ultrastructural changes inflicted on the gastric mucosa in chronic gastritis and fibrosis. This hypothesis, if substantiated will provide for therapy which will be based on the pathogenesis of the disease and which will be cheaper and easily available to most. It will also add impetus to the early eradication of Helicobacter pylori, which would prevent chronic gastritis and hence gastric fibrosis.

Dural sinus thrombosis presenting as unilateral lobar haematomas with mass effect: an easily misdiagnosed cause of cerebral haemorrhage

Dural sinus thrombosis has protean clinical and radiological manifestations ranging from minimal effacement of sulci with no symptoms to severe haemorrhagic infarcts associated with focal deficits, coma and even death. An uncommon form of presentation is characterized by unilateral lobar haemorrhage associated with extensive oedema and parenchymal distortion. In an acute presentation, this might resemble haemorrhage into a tumour. In delayed presentations, the haematoma, being iso- or hypodense and showing peripheral ring-like enhancement, can mimic aggressive tumours or infective processes. As this is an uncommon condition, misdiagnosis is common with the potential for mismanagement and adverse outcomes. We present five such consecutive cases that were initially misdiagnosed as other entities. Each of these cases on closer inspection show features observed on CT and MRI that should have suggested a diagnosis of dural venous sinus thrombosis. One of these cases progressed to not only extensively involve the superficial sinuses but also the deep veins, with a significant adverse outcome. The imaging features of this interesting variant of dural sinus thrombosis are reviewed. The haemodynamic basis for haemorrhage and anatomical basis for the lateralization of the lesions are discussed.

Sensorineural hearing loss following acute bacterial meningitis in non-neonates

OBJECTIVE

Sensorineural hearing loss (SNHL) is an important sequelae of acute bacterial meningitis (ABM) in children. This study was undertaken to determine the incidence of SNHL following meningitis in non-neonates and its correlation with various factors.

METHODS

Children between the ages of 1 month and 12 years with ABM admitted in a teaching hospital over a period of 18 months were enrolled. Detailed history was taken, clinical examination performed and cerebrospinal fluid analyzed at commencement of therapy, 48 hours later and at the end of treatment. On discharge brainstem evoked response audiometry (BERA) was recorded. Data were analyzed using appropriate statistical tests.

RESULTS

Out of 32 children enrolled, 9 (28.1%) developed SNHL, bilateral in 21.9% and unilateral in 6.2%. Among hearing impaired subjects, 11.2% had mild while 44.4% each had moderate and profound hearing loss. Age, presence of vomiting, altered sensorium seizures and aminoglycoside usage were not significantly different in those with and without SNHL, but the total duration of fever was (p<0.05). There was significantly higher protein content and neutrophils in the second CSF sample of those with SNHL.

CONCLUSION

There is a greater than 50% probability of the child developing SNHL if neutrophil percentage in the second CSF is 80% or more. Since the overall risk of SNHL is significant in children with meningitis, it is recommended that BERA be recorded in all, so that early intervention may be possible.

Advances in understanding the mode of action of MBT fungicide used in wood protection

Interactions between methylene bisthiocyanate (MBT) and common wood degrading fungi of Pinus radiata were investigated The minimum inhibitory concentration (MIC) of MBT was determined in yeastmalt liquid medium and on radiata pine Higher treatment concentrations of MBT were required to control fungal growth on wood than in liquid culture irrespective of the test fungus used There were significant differences between the test fungi for MIC levels of MBT on diptreated wood with the highest degree of tolerance observed for Trichoderma viride (MIC le; 064 w/v) Further experiments suggested that vapour action and diffusibility both contributed to the fungitoxicity of MBT