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Biomedical subjects

M Louw

Publications and source records attributed to M Louw.

At least 19 recordsLinked to original sources
PubMed2006

Ultrasound-assisted transthoracic biopsy: fine-needle aspiration or cutting-needle biopsy?

The present study compared the diagnostic yield of ultrasound-assisted cutting-needle biopsy (CNB) and fine-needle aspiration biopsy (FNAB) in chest lesions. A physician performed ultrasound and FNAB with a 22-G spinal needle in all patients, directly followed by a 14-G CNB in patients without contraindication. A total of 155 consecutive lesions arising from the lung (74%), pleura (12%), mediastinum (11%) or chest wall (3%) in patients with a final diagnosis of lung carcinoma (74%), other malignant tumours (12%), non-neoplastic disease (9%) or unknown (5%) were prospectively included. The overall diagnostic yield was 87%. Combined specimens were obtained in 123 lesions (79%). In these, yields of FNAB, CNB and both methods combined were 82, 76 and 89%, respectively. FNAB was significantly better than CNB in lung carcinoma (95 versus 81%) but CNB was superior in noncarcinomatous tumours and in benign lesions. On-site cytology was 90% sensitive and 100% specific for predicting a positive FNAB. One patient required drainage for pneumothorax (0.6%). Ultrasound-assisted fine-needle aspiration biopsy performed by chest physicians is an accurate and safe initial diagnostic procedure in patients with a high clinical probability of lung carcinoma. All other patients should undergo concurrent fine-needle aspiration biopsy and cutting-needle biopsy.

Adult↗
PubMed2006

Transbronchial needle aspirates: how many passes per target site?

Transbronchial needle aspiration is a bronchoscopic sampling method for a variety of bronchial and pulmonary lesions. The present study investigated whether and how serial needle passes contribute to the yield of transbronchial needle aspiration at specific target sites. A total of 1,562 needle passes, performed at 374 target sites in 245 patients with neoplastic disease (82%), non-neoplastic disease (15%) or undiagnosed lesions (3%), were prospectively recorded and rated for anatomical location, size, bronchoscopic appearance and underlying disease. Positive aspirates were obtained in 75% of patients and at 68% of target sites. A diagnosis was established with the first, second, third and fourth needle pass at 64, 87, 95 and 98% of targets, respectively. The absolute yield varied strongly with target site features, but the stepwise increment to the maximum yield provided by serial passes was similar across target sites. In conclusion, three transbronchial needle passes per site are appropriate when only a tissue diagnosis is sought and when alternative sites or sampling modalities are available. At least four or five passes should be carried out at lymph node stations critical for the staging of lung cancer.

Adolescent↗
PubMed2000

Ultrasonography-guided fine-needle aspiration for the assessment of cervical metastases.

OBJECTIVE: To assess the value of ultrasonography (US) combined with fine-needle aspiration (FNA) cytology for the investigation of lymph node metastases in patients with head and neck cancer. DESIGN: Comparison of clinical examination (palpation) and preoperative US-FNA examination results of cervical nodes in a sample of patients with head and neck cancer. The histological features of the neck dissection specimens are used to validate these 2 variables. SETTING: A head and neck oncology service in a tertiary referral hospital. PATIENTS: A consecutive sample of 56 patients with head and neck squamous cell carcinoma, first seen between April 1, 1996, and July 30, 1998, who had neck dissections performed after the US-FNA examination. INTERVENTION: Cervical US-FNA preoperatively, followed by elective or therapeutic radical modified or selective neck dissection. MAIN OUTCOME MEASURES: The histological examination results of subsequent neck dissection specimens are used to determine the sensitivity, specificity, and accuracy of US-FNA for individual nodes. Second, the results of node staging by clinical examination and US-FNA examination are compared. RESULTS: The sensitivity was 89.2%; specificity, 98.1%; and accuracy, 94.5%. Correct node stages were obtained in 52 (93%) of the patients using US-FNA compared with 34 (61%) using palpation. CONCLUSIONS: Ultrasonography combined with FNA is a highly accurate technique for the investigation of cervical lymph node metastases. A more accurate diagnosis may result in more appropriate treatment, particularly in a setting with limited resources. Retropharyngeal nodes, micrometastases, and lymph nodes smaller than 4 mm are limitations of US-FNA. Ultrasonography combined with FNA is a useful technique for the staging of head and neck cancer.

Biopsy, Needle↗
PubMed2000

Nocardial infection as a complication of HIV in South Africa.

OBJECTIVES: To assess the occurrence, clinical and microbiological features of nocardial infections complicating HIV in Soweto, South Africa. METHODS: A prospective study was carried out over a 2-year period. Patients were identified after isolation of Nocardia spp. from a clinical specimen. Clinical details were recorded. The nocardial isolates were identified to species level and susceptibility tests performed. RESULTS: Ten patients were identified as having nocardial disease complicating HIV. Clinical presentations were pulmonary (five patients), pulmonary and cerebral (one patient), cerebral (one patient) and skin and soft tissue infection of the lower limb (three patients). Three infections were fatal. The isolates were Nocardia asteroides (seven patients), N. farcinica (two patients) and Nocardia spp. (one). Isolates of N. farcinica demonstrated opacification of Middlebrook agar. All isolates were sensitive to amikacin and minocycline. Most nocardial isolates were susceptible to cefotaxime, imipenem and coamoxiclav. In vitro resistance to cotrimoxazole was present in five. CONCLUSIONS: Nocardial infection occurs as a complication of HIV infection in the Republic of South Africa. Pulmonary cases may be difficult to distinguish from tuberculosis. Nocardia asteroides is the most common species isolated. Nocardia farcinica has resistance to multiple antibacterial agents and demonstrates opacification of Middlebrook agar, a useful screening test for this species. Agents with good in vitro antinocardial activity were amikacin, minocycline, cefotaxime, imipenem and coamoxiclav. There was a high level of resistance in vitro to cotrimoxazole.

AIDS-Related Opportunistic Infections↗
PubMed1995

The moth-eaten alopecia of secondary syphilis. A histopathological study of 12 patients.

Moth-eaten alopecia (MEA) is a characteristic manifestation of secondary syphilis. Clinically, this form of alopecia may be confused with trichotillomania, traction alopecia, and alopecia areata. The histopathological features of the latter conditions are well described, but information regarding the histology of syphilitic MEA is sparse. We systematically documented the histopathological features of 12 patients with MEA. Characteristic features included follicular plugging; a sparse, perivascular and perifollicular lymphocytic infiltrate; telogenization and follicle-oriented melanin clumping.

Adult↗
PubMed1994

Papulonecrotic tuberculid. A clinical, histopathological, and immunohistochemical study of 15 patients.

We report 10 women and five men with papulonecrotic tuberculid, an uncommon form of cutaneous tuberculosis (TB). The mean age was 22.6 years (range, 2 1/2-35 years) at presentation. The Mantoux test was strongly positive in 13 patients. Five patients showed presumptive evidence of associated TB; in one case, the presence of TB was proven by culture. Response to anti-TB was dramatic in all cases. Clinical findings were similar to those previously published. We emphasize the simultaneous occurrence of erythema induratum, associated Takayasu's disease, possible associated phlebitic tuberculid, and clinical mimicry of acute bacterial endocarditis. The main histopathological findings obtained from 27 biopsy specimens included dermal necrosis (26 of 27 cases), a poorly formed granulomatous infiltrate (27 of 27 cases), vasculitis (11 of 27 cases), perivascular spongy edema (11 of 27 cases), and follicular necrosis or suppuration (five of 27 cases). A Ziehl-Neelsen stain was negative in all biopsy specimens. Immunohistochemical labeling revealed a preponderance of T-lymphocytes (UCHL-1+), monocytes-macrophages (S-100+), and Langerhans cells (ACT+), indicative of a type IV hypersensitivity reaction. B-lymphocytes (L26+) were sparse. Conditions that may be confused with PNT on clinical or histopathological ground include pityriasis lichenoides et varioliformis acuta, papular urticaria, papulopustular syphilide, miliary TB, septicemia, perforating granuloma annulare, chondrodermatitis nodularis, reactive perforating collagenosis, allergic granulomatosis, suppurative folliculitis, and infectious causes of palisading granulomas. Papulonecrotic tuberculid has distinct clinical, histopathological, and immunohistochemical features. Awareness of this entity is important since an appropriate diagnosis is necessary for the institution of timely curative treatment.

Adolescent↗
PubMed1992

Papulonecrotic tuberculid. Identification of Mycobacterium tuberculosis DNA by polymerase chain reaction.

Sections from 22 formalin-fixed, paraffin-embedded skin biopsies from 12 patients with papulonecrotic tuberculid (PNT) were examined for the presence of Mycobacterium tuberculosis DNA with use of the polymerase chain reaction. All patients had a positive tuberculin skin test and a compatible clinical picture and responded to antituberculous therapy. Histological examination showed the typical morphology of PNT lesions with dermal necrosis surrounded by an ill-formed granulomatous infiltrate. Mycobacterial DNA was detected in 11 of the 22 biopsies. None of the negative controls showed positive DNA identification by amplification. Great care was taken in avoiding false-positive results due to contamination. After reviewing the literature, we believe this is the first time that PNT lesions have been investigated by PCR for the presence of mycobacterial DNA. These findings provide direct proof that mycobacterial products are present in PNT lesions and support the theory that this organism is in some way responsible for the development of PNT.

Adolescent↗
PubMed1991

Down's syndrome in South Africa--incidence, maternal age and utilisation of prenatal diagnosis.

Down's syndrome (DS) is the most common chromosomal cause of metal retardation, and amniocentesis is the most significant factor affecting its prevalence. In South Africa, prenatal cytogenetic diagnoses have been available for just over a decade and the utilisation and effect of this procedure in the white population born between 1980 and 1984 was evaluated. On the basis of pooled data involving 4,939,640 births, an overall world mean rate for DS of 1,34/1,000 live births (mainly Caucasian) for single-year maternal ages was calculated. Accordingly, 58 cases of DS were expected in the 40-year and older maternal age group in South Africa. Only 34 cases (59%) were detected prenatally, and a further 3 cases were identified by the notification system during the same period and in the same maternal age group. Another 24 DS cases in the maternal age group of 40 years and over could thus potentially have been detected prenatally and prevented, while 21 cases in this age group (36%) could not be accounted for at all. Cost-benefit analyses are shown and the number of amniocenteses required for various maternal age groups to affect the prevention of DS is calculated.

Adult↗
PubMed1987

Gaucher's disease in the Cape coloured population of the RSA, including a family with 5 affected siblings.

Nine Cape Coloured children from 4 families with severe non-neuropathic Gaucher's disease are documented. The diagnosis was confirmed histologically in the bone marrow, spleen and liver, and by serum acid phosphatase and leucocyte beta-glucosidase assays. This represents a minimum prevalence for Gaucher's disease of 1 in 247,350 in this population and an approximate genetic carrier rate of 1 in 230 for the abnormal gene. A family with 5 affected siblings is recorded. The severe early clinical expression documented in these coloured patients is similar to that described in the Afrikaner population and differs from the less severe expression of Gaucher's disease in the South African Ashkenazi Jewish population. Gaucher's disease in the Cape Coloured population presents with a precocious onset, causes severe complications and progresses rapidly.

Black People↗
PubMed1978

Focal dermal hypoplasia (Goltz syndrome): case reports.

Two Cape Coloured children, both with physical stigmata of Goltz syndrome, are described. Accurate diagnosis of congenital defects in the newborn allows optimal planning of surgical treatment and more accurate prognosis and genetic counselling.

Abnormalities, Multiple↗
PubMed1977

Effects of hexachlorobenzene feeding and iron overload on enzymes of haem biosynthesis and cytochrome P 450 in rat liver.

1. The effect of hexachlorobenzene feeding on liver delta-aminolaevulinate synthase, uroporphyrinogen decarboxylase and cytochrome P 450 was studied at various time-intervals in siderotic and non-siderotic rats. 2 In the non-siderotic group hexachlorobenzene feeding led to a progress decrease in liver uroporphyrinogen decarboxylase activity, accompanied by a progressive increase in delta-aminolaevulinate synthase activity. Cytochrome P 450 concentrations were above normal throughout but fell toward the end of the experiment. 3. Similar but more marked changes were found in the siderotic animals. The fall in uroporphyrinogen decarboxylase activity occurred earlier and was significantly greater in these animals, whereas the increase in delta-aminolaevulinate synthase activity was consistently larger. Liver cytochrome P 450 concentration also rose but to a lesser extent than that in the non-siderotic rats. 4. Hexachlobenzene-induced porphyria would seem to be attributable to inhibition or inactivation of hepatic uroporphyrinogen decarboxylase. Hepatic siderosis has a synergistic effect with hexachlorobenzene on this enzyme and may exert additional effects by promoting cytochrome P 450 turnover.

5-Aminolevulinate Synthetase↗
PubMedDate not supplied

Urine cytology as a screening test for bladder infiltration in cervical cancer.

Ultrasound is currently used as a screening test for bladder infiltration in patients with advanced-stage cervical cancer at our institution. Cystoscopy is reserved for patients with abnormal bladder ultrasound findings. This study was undertaken to reevaluate this policy and to compare the results of different screening tests. The study was carried out in Pretoria academic complex. All newly diagnosed cervical carcinoma patients stage II and above were included in this study. The standard staging investigations were done on all patients. In addition, urine midstream and catheter specimens were sent for cytology. Cystoscopy and biopsy were performed on all patients. Two hundred twenty-eight patients were enrolled into this study. At cystoscopy, 47 patients had bladder mucosa suspicious of malignant infiltration, of which 17 had bladder mucosa infiltration diagnosed on histology. Urine catheter cytology has a sensitivity of 94% and specificity of 82% for bladder mucosa infiltration. The predictive value of a positive test is 31% and for a negative test is 99%. Catheter urine cytology is a very useful screening test for bladder infiltration in patients with cervical cancer. Cystoscopy should be reserved for patients with abnormal urine cytology in resource-poor settings with a large burden of disease.

Biopsy↗