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Biomedical subjects

J A Khan

Publications and source records attributed to J A Khan.

At least 19 recordsLinked to original sources
PubMed1992

Quantitation by fast-atom bombardment mass spectrometry: assay of cytidine 3',5'-cyclic monophosphate-responsive protein kinase.

A protein kinase, stimulated by cytidine 3',5'-cyclic monophosphate, is conventionally assayed by monitoring the incorporation of radiolabelled phosphate from adenosine triphosphate into a histone substrate. Here the assay of the protein kinase is carried out by positive-ion fast-atom bombardment mass spectrometric analysis of the enzyme incubation mixture after the reaction has been terminated. The data so obtained show good agreement with data obtained by the conventional radiometric assay: the intrinsic advantage of the mass spectrometric assay is the capacity for multiple component monitoring; the ability of the kinase to bind competing cyclic nucleotides together with integral adenosine triphosphatase (ATPase) and phosphodiesterase activity can also be assessed.

Adenosine Triphosphate↗
PubMed1992

A proposal for a bean common mosaic subgroup of potyviruses.

In order to elucidate the taxonomic positions of bean common mosaic virus (BCMV) and blackeye cowpea mosaic virus (B1CMV), several strains of these viruses were compared on the basis of host ranges, antigenic properties established with antisera to virions and to N-terminal peptide domains of their coat proteins, and high performance liquid chromatographic peptide profiles. The comparison includes three strains of BCMV, viz. NL1, NL3 and NY15, four strains of B1CMV, viz. Fla, Ind, NR, and W, and the Moroccan isolate (Mor) of cowpea aphid-borne mosaic virus (CABMV), formerly designated as B1CMV-Mor. Based on these parameters, Fla, NR, and W are strains of one virus, whereas NL3, Ind and CABMV-Mor (and possibly NL1 and NY15) are separate viruses. In view of these characteristics which allow similar viruses to be separated, we propose that these viruses be included in a bean common mosaic subgroup of the genus Potyvirus.

Capsid↗
PubMed1991

Effect of contact lens removal or displacement on intraocular pressure.

We conducted a controlled, prospective study involving 102 healthy volunteers to determine the effects of contact lens removal and contact lens displacement on subsequent intraocular pressure measurements. Intraocular pressure was measured at baseline, immediately after contact lens removal or displacement, and 5 minutes thereafter. The method of lens removal was either sliding displacement (51 eyes) or plucking (51 eyes). Right eyes were used for the test, and left eyes served as controls. Compared with baseline measurements, mean intraocular pressure immediately after plucking the lens was 0.8 mm Hg lower (P less than .01) and after sliding the lens was 0.5 mm Hg higher (P less than .05). Intraocular pressure changes of 4.0 mm Hg or more occurred in eight (15.6%) of 51 eyes in the pluck group vs four (7.8%) of 51 control eyes and in two (3.9%) of 51 eyes in the slide group vs zero of 51 control eyes. Compared with baseline, significant differences (P less than .05) were not found 5 minutes later. Clinicians who wish to minimize the influence of contact lens removal on tonometry readings should wait several minutes after contact lens removal before measuring intraocular pressure.

Adolescent↗
PubMed1991

Comparison of Oculab Tono-Pen readings obtained from various corneal and scleral locations.

When estimating intraocular pressure in patients who are uncooperative or who have central corneal disturbances, the physician may find it either impractical or undesirable to place the small tip of a portable electronic applanation tonometer (Tono-Pen) over the central cornea. To gauge better the usefulness of Tono-Pen readings obtained from various locations, we compared such readings measured through the central cornea, midperipheral cornea, limbal cornea, and sclera of 15 cannulated eye bank eyes. Mean Tono-Pen readings from the midperipheral and clear limbal cornea did not differ significantly from central corneal readings over a 10- to 35-mm Hg range of intraocular pressures and were within +/- 2.4 mm Hg of mean central corneal readings. Mean readings taken from the sclera, however, were 8.8 to 17.0 mm Hg higher than mean central corneal readings over the 10- to 40-mm Hg range. We concluded that multiple noncentral corneal readings with the Tono-Pen provided a useful approximation of intraocular pressure, whereas scleral readings did not.

Cornea↗
PubMed1991

Sebaceous and meibomian carcinomas of the eyelid. Recognition, diagnosis, and management.

Sebaceous carcinoma of the eyelid is frequently misdiagnosed clinically and histopathologically. The tumor may present as a lid mass, recurrent chalazion, or diffuse unilateral blepharoconjunctivitis. Fifty percent of cases are misdiagnosed, often by an inexperienced general pathologist interpreting the initial biopsy. Frozen-section monitoring of surgical margins has been reported unreliable in 25% of cases. Mohs surgery is also unreliable in cases where there is pagetoid intraepithelial spread or skip lesions. This tumor may spread regionally into the lacrimal secretory and excretory systems, to regional lymph nodes, and rarely disseminate hematogenously. Guidelines for management are discussed.

Eyelid Neoplasms↗
PubMed1991

Combination punctal dilator and lacrimal probe.

A combination punctal dilator and lacrimal probe intended for diagnostic and therapeutic probing of the entire lacrimal outflow system is described. This instrument allows for a single-handed comfortable transition from dilating to probing without release of lateral lid traction. The dilator-probe has a familiar pencil-like maneuverability and may be customized to satisfy the surgeon's preferences with regard to probe caliber and punctal dilator style.

Humans↗
PubMed1991

Cyanoacrylate-assisted trial eyelid repositioning for epiphora.

Cyanoacrylate skin adhesions of the lateral lower eyelid reinforced with surgical tape were created in three patients in order to temporarily correct epiphora due to lid laxity, eyelid malposition, punctal malposition or punctum-eyelid apposition. The cyanoacrylate adhesions resulted in relief of epiphora or aided in establishing the cause of epiphora, and allowed the patient to "sample" the anticipated benefits of corrective lid surgery. Trial eyelid repositioning may be useful in cases where there is only mild or equivocal punctal malposition or lid laxity and the surgeon wishes to predict the effect of corrective lid surgery.

Cyanoacrylates↗
PubMed1991

Sub-cilial sliding skin-muscle flap repair of anterior lamella lower eyelid defects.

Defects of the anterior lamella of the lower eyelid are common following Mohs micrographic surgery. Often, such defects are repaired with free skin grafts. The author reviews the treatment of such defects utilizing a single subcilial incision to develop a sliding blepharoplasty-type flap, which is advanced medially or laterally, as needed, into the defect. Larger defects may require Putterman's modified Tenzel flap. Final lid function, position, and cosmesis were superior to the results expected from free skin grafts alone in four of the author's five cases. Indications, limitations, modifications, technical aspects, benefits and potential pitfalls of reconstructive subcilial flaps are discussed.

Eyelids↗
PubMed1991

Supervised training of practical procedures in the internal medicine residency.

In order to get feedback whether the medical residents are getting adequate supervised training to perform practical procedures, a questionnaire was distributed among the residents asking their involvement in sixteen frequently performed procedures in the medical unit of the Aga Khan University Medical Centre. Though the residents were satisfied about their training in doing lumbar punctures, pleural and peritoneal aspirations, bone marrow aspiration and trephine and chest tubes placement, they showed their concern about training in putting central lines, venous cut downs, cardiac pacing and biopsies. A better schedule training programme, organized subspecialty rotation, continuous evaluation of resident's skill, credentialing procedures and willingness on the part of faculty to teach and residents to learn may improve the training.

Internal Medicine↗
PubMed1990

Dermal graft. Alternative to Gunderson flap allows fitting scleral shell over sensitive cornea.

Corneal discomfort often prevents the successful wearing of a cosmetic scleral shell. Such sensitive corneas are traditionally covered with a Gunderson conjunctival flap. I describe two patients in whom preexisting severe conjunctival scarring precluded the possibility of developing a Gunderson flap. An alternative procedure in which autogenous split-thickness dermal grafts were sutured over the sensitive cornea was utilized in each patient. The dermal grafts reepithelialized with mucosa within 4 weeks, and both patients were then able to retain an ocular prosthesis without discomfort. I conclude that satisfactory corneal coverage may be obtained with a dermal graft when conjunctival scarring precludes the use of a Gunderson flap.

Adult↗
PubMed1990

Obstructive jaundice: an unusual presentation of amoebic liver abscess.

A case of amoebic liver abscess with obstructive jaundice is described. Treatment with metronidazole resulted in improved general condition while the jaundice continued to increase. The abscess was twice aspirated and a total of 500 ml fluid was obtained with no improvement in the jaundice. A percutaneous catheter was introduced and drained 300-400 ml bile a day, decreasing and stopping over a week. The jaundice progressively improved.

Cholestasis↗
PubMed1990

Acute respiratory infections in children: a case management intervention in Abbottabad District, Pakistan.

Between 1985 and 1987, a community-based case-management programme for acute lower respiratory infection (ALRI) was conducted in a rural district of northern Pakistan. The impact on infant and child mortality of this programme, which included active case-finding and maternal health education, was evaluated. In 1985-86, the ALRI-specific mortality rate among children less than 5 years old in 31 intervention villages was 6.3 deaths per 1000 children per year, compared with 14.4 in seven control villages (P = 0.0001). Within one year of the interventions being extended to the control villages in 1987, the ALRI-specific mortality rate in these villages dropped by 55% to 6.5 per 1000 children per year (P = 0.06). The total child mortality rate in 1985-86 was 29.0 per 1000 children per year in the intervention villages and 39.4 per 1000 children in the control villages, a difference of 26% (P = 0.01). With the interventions in 1987, the total child mortality rate in the control villages declined by 29% to 27.8 per 1000 children per year (P = 0.09). Similar intervention-associated declines in the infant mortality rate were also observed. Case management of acute respiratory infection by village-level community health workers backed up by local health centre staff appeared to significantly reduce both ALRI-specific and total infant and child mortality rates in this setting.

Acute Disease↗