Dynamic responses of photosystem II in the Namib Desert shrub, Zygophyllum prismatocarpum, during and after foliar deposition of limestone dust.

The effects of limestone dust deposition on vegetation in desert ecosystems have not yet been reported. We investigated these effects in a succulent shrub from the Namib Desert at a limestone quarry near Skorpion Zinc mine (Namibia). Effects of limestone dust were determined in Zygophyllum prismatocarpum (dollar bush) plants with heavy, moderate and no visible foliar dust cover by means of chlorophyll a fluorescence measurements. Limestone dust deposition decreased overall plant performance through loss of chlorophyll content, inhibition of CO(2) assimilation, uncoupling of the oxygen-evolving complex and decreased electron transport. Importantly, dynamic recovery occurred after termination of limestone extraction at the quarry. Recovery was accelerated by rainfall, mainly because of dust removal from leaves and stimulation of new growth. These results indicate that limestone dust has severe effects on photosynthesis in desert shrubs, but that recovery is possible and that, in arid environments, this process is modulated by rainfall.

Dark chilling inhibition of photosynthesis and symbiotic nitrogen fixation in soybean during pod filling.

The growth stage of a soybean [Glycine max (L.) Merrill] plant may influence its physiological response to dark chilling. Opposed to vegetative development, the intense nutrient and energy requirements of the developing seeds during pod filling could cause additional chilling damage and decreased recovery capacity. Previously, we investigated dark chilling tolerance during vegetative development in two soybean genotypes, 'Maple Arrow' and 'Fiskeby V' and consistently found that photosynthesis and symbiotic nitrogen fixation (SNF) was less affected by dark chilling in 'Maple Arrow'. In this study we describe the dark chilling response of the same genotypes during pod filling. Our aim was to establish whether the potential selection criteria for dark chilling tolerance, identified during vegetative development, was equally sensitive during pod filling. The results indicate that photosynthesis is less affected by dark chilling in 'Maple Arrow' than in 'Fiskeby V', not only during vegetative development, but also during the critical reproductive stage of pod filling. 'Fiskeby V' also lacks the ability to restore normal photosynthetic capacity during an extended recovery treatment. The decrease of nodule ureide content indicates that SNF was inhibited to a similar extent in both genotypes. Nodule ureide content was reduced more than stem ureide content, suggesting that the former is a more sensitive indicator of chilling stress effects on SNF. The results indicate that certain photosynthetic and fluorescence parameters are sensitive indicators of dark chilling tolerance throughout plant development and should prove valuable in future breeding programmes aimed at increasing the chilling tolerance of soybean.

99mTc-MIBI stress-rest myocardial perfusion scintigraphy in patients with complete left bundle branch block.

BACKGROUND: Patients with complete left bundle branch block (LBBB) often show a false-positive ischaemic pattern in the interventricular septum on thallium-201 (201TI) stress-rest myocardial perfusion scintigraphy. Equivocal results have been reported with technetium-99m labelled hexakis-methoxyisobutyl isonitrile (99mTc-MIBI) in such patients. The aim of this retrospective study was to determine the effect of LBBB on the septal uptake of 99mTc-MIBI during stress-rest single photon emission computed tomography (SPECT) scintigraphy. METHODS: We studied 75 consecutive patients with LBBB, referred for 99mTc-MIBI stress-rest SPECT. Studies were evaluated by visual analysis using a semi-quantitative grading technique. In all patients with abnormal septal segments, the presence or absence of ischaemic heart disease was confirmed either clinically or by means of angiographical examination. RESULTS: Forty-three patients (57.3%) had completely normal studies. Only 15 (20%) had septal abnormalities (11 with reversible and 4 with fixed defects), while 17 patients (22.7% had abnormal segments in areas other than the interventricular septum. Except for 1 patient lost to follow-up, ischaemic heart disease was confirmed in all the patients with septal changes. CONCLUSION: We conclude that 99mTc-MIBI is more specific than 201TI for identifying ischaemic heart disease in the presence of LBBB.

Imaging infection and inflammation in an African environment: comparison of 99Tcm-HMPAO-labelled leukocytes and 67Ga-citrate.

A considerable segment of the population of South Africa has a disease spectrum similar to those of the industrialized countries. However, a much larger proportion of its inhabitants comes from historically disadvantaged communities and is plagued by diseases typical of the developing world. Infectious diseases head the list as a cause of mortality in certain age groups. We have studied 108 patients presenting with a wide array of infections. Fifty-eight patients were examined with 67Ga-citrate and with 99Tcm-HMPAO-labelled leukocytes, 40 with leukocytes alone and 10 who had a high pre-test probability of tuberculosis with 67Ga only. The sensitivity and specificity of 99Tcm-labelled leukocyte scintigraphy in the 58 patients who had both studies were 89 and 84%, respectively, while the corresponding values for 67Ga scintigraphy were 81 and 74%, respectively. The overall sensitivity and specificity for 99Tcm-labelled leukocytes for detecting inflammatory sites in all 98 cases were 92 and 89%, respectively. Although labelled leukocytes were the better of the two agents for the early diagnosis of infections with a high probability of neutrophil infiltration, 67Ga remains an excellent alternative. It is the first choice in patients in whom tuberculosis or a neoplastic process is suspected as a cause of fever. It is also safer to use in areas where labelling of leukocytes is inadvisable because of inadequate sterility or where the risk is high of infecting other patients or staff with HIV.

[The effect of heparin induced increase of free plasma thyroxine on cardiac rhythm after myocardial infarction]. / Die effek van heparien-geïnduseerde styging in vrye plasmatiroksien op die hartritme na miokardiale infarksie.

It is well known that an acute myocardial infarction is accompanied by a rise in levels of plasma free fatty acids (FFA), which may lead to a subsequent increase in cardiac arrhythmias. Administration of heparin to patients after an acute myocardial infarction gives rise to an increase both in plasma FFA levels and plasma free thyroxine levels. If administered without a fatty meal the rise in FFA is not accompanied by an increase in arrhythmias. The effect of the heparin-induced rise in plasma free thyroxine on cardiac rhythm has never been investigated. The aim of the present study was to investigate a possible arrhythmic effect of a heparin induced increase in plasma free thyroxine in a group of patients with acute myocardial infarction. We were able to confirm a significant heparin-induced rise in plasma free thyroxine levels, as measured by the effective thyroxine ratio. Although a slightly significant increase in ventricular premature beats could be demonstrated after heparin administration when using the Wilcoxon rank sum test for statistical analysis (but not when the paired t-test was utilized), no significant correlation with free thyroxine levels could be found. Heparin administration to patients suffering from myocardial infarction seems to be safe in terms of a possible arrhythmic effect.

[Metastatic calcifications as demonstrated by technetium-99m-pyrophosphate bone scanning. Case reports]. / Metastatiese verkalkinge soos aangetoon met tegnesium-99m-pirofosfaat-beenflikkergrafie. Gevalbesprekinge.

Two cases of chronic renal failure showing very interesting technetium-99m-pyrophosphate bone scans are presented. In both cases striking uptake of activity was shown in the left ventricle of the heart, the mucosa of the stomach and in both lungs. This picture was attributed to metastatic calcification in these organs. Cases of metastatic calcification demonstrated with bone-seeking agents have been presented previously, but have mainly shown intense uptake of activity in the lungs and in a few cases, and to a lesser degree, in the stomach. However, we believe that our cases are unique in showing especially the left ventricle of the heart as well as the mucosa of th stomach with exceptional clarity.

[Ventilation studies of the lung with krypton-81m]. / Ventilasiestudies van die long met kripton-81m.

During a 2-year study period it was found that krypton-81m was useful in routine clinical practice. During this period 1563 technetium-99m perfusion studies and 807 krypton-81m ventilation studies were performed. A distinct advantage of krypton-81m was the ease with which multiple views could be obtained. These views could be directly compared with those of preceding perfusion studies. However, interruptions in the regular supply of rubidium-81/krypton-81m generators affected 17,1% of perfusion studies and xenon-127 should be a suitable substitute for these periods.

[The diagnosis of sarcoidosis with gallium-67. A case report]. / Die diagnose van sarkoïdose met gallium-67. 'n Gevalbespreking.

Uptake of gallium-67 in the chest is a relatively nonspecific indicator of active disease. In patients with suspected sarcoidosis a specific diagnosis can often be made if the head and neck are included during imaging. Seventy-five per cent of patients with sarcoid lesions in the lungs and mediastinum show uptake of the isotope in the salivary glands. If, in addition, the lacrimal glands concentrate the gallium, a diagnosis of sarcoidosis may be made with confidence. A case of mediastinal sarcoidosis, illustrating uptake of gallium-67 in the parotid and lacrimal glands, is discussed.

[The effect of rooibos tea on iron absorption]. / Die effek van rooibostee op ysterabsorpsie.

A study was carried out to determine if rooibos tea (Aspalathus linearis) has a deleterious effect on iron absorption similar to that of ordinary tea (Camellia sinensis). Three groups of volunteers, each consisting of 10 healthy young men comparable with regard to iron status and body dimensions, were studied. After ingestion of 1 muCi 59Fe and 16 mg of elemental iron, group A drank rooibos tea, group B ordinary tea and group C boiled water. Iron absorption was measured 14 days later with a whole body counter. Mean iron absorption after ingestion of rooibos tea, ordinary tea, and water was 7,25%, 1,70% and 9,34% respectively. In contrast to ordinary tea (P less than 0,0001), rooibos tea did not affect iron absorption significantly. The ascorbic acid content of rooibos tea varies between 121,8 and 154,9 mumol/l, depending on the method of preparation. Rooibos tea contains small amounts of iron, magnesium, phosphorus, sodium, chloride and potassium. These findings have practical nutritional and therapeutic implications.

Two simple inexpensive photographic methods for viewing ECG-gated radionuclide blood pool images.

Although the ECG-gated radionuclide blood pool scan (GBPS) has become an established method for studying regional myocardial wall motion, it is usually performed with the aid of an expensive computer system. A simple, inexpensive method was developed to view gated radionuclide blood images by a film loop and a photographic motion detection (PHOMOT) technique. These techniques were compared with left ventricular cine angiography in 15 patients. Segmental wall movement (78 segments) showed identical results in 92% of cases. In all patients the same diagnosis was arrived at by GBPS and cine angiography. The photographic techniques developed offer a simple screening procedure to reduce cardiac catheterization in patients with suspected abnormalities of left ventricular wall contraction.

[Mumps meningitis--bromine-82 partition test and cerebrospinal fluid glucose]. / Pampoentjie--meningitis--broom-82 partisietoets en serebrospinale vog glukose.

A case of mumps meningitis is reported where a low cerebrospinal fluid (CSF) glucose level, a positive bromine-82 partition test and the fact that the patient's sister had recently had tuberculous meningitis complicated the diagnosis. Mumps meningitis may be associated with low CSF glucose levels. Patients with viral meningitis usually have normal CSF glucose levels, and, during a recent study, false-positive results of 82Br partition tests were not found. Mumps meningitis, however, proves to be an important exception.

[Value of scintigraphy in the treatment of single nodules of the thyroid]. / Die waarde van flikkergrafie in die hantering van enkelnodules van die tiroïed

The value of radionuclide scanning of the thyroid gland was investigated in 125 patients with solitary thyroid nodules. Fifty-seven of the 95 patients with 'cold' nodules underwent surgery. The incidence of malignant nodules in this group was 16%; therefore surgery is recommended for all solitary 'cold' nodules. Of the 30 patients with 'warm' nodules, 20 were treated surgically and in only 1 patient was the nodule malignant. This incidence is probably not significant. Surgery is, however, also recommended for all solitary 'warm' nodules because of the possibility of toxic change. Accurate planning of the surgical procedure depends on any function of the nodule in question and this can be determined with certainty only by radionuclide scanning.

[Intravenous radioisotope angiography in carotid-cavernous fistula]. / Binneaarse radio-isotoop angiografie in karotis-kaverneuse fistels

The use of intravenous radio-isotope angiography in 3 cases of unilateral carotid-cavernous sinus fistula is described. The lesion gives a characteristic image pattern distinguishable from that of arteriovenous malformation in this region. An abnormal registration of intense radioactivity is seen in the early phases, accurately localised to the cavernous sinus, with a distinctive sigmoid-shaped configuration. Rapid disappearance by a paradoxical apparent increase in blood flow to the ipsilateral hemicranium. This is attributed to the massively arterialised venous drainage. This technique of demonstrating the cerebral circulation dynamically is considered a valuable diagnostic supplement to the static scintiscan and to conventional roentgen arteriography in this lesion.